Troubleshooting Mobile Phone Faults

Troubleshooting Mobile Phone Faults:

Troubleshooting:

Methods of search of malfunctions. Repair includes the works connected with replacement of components, repair of units, blocks, details, elimination of short circuits, restoration and adjustment of the device. Search of malfunctions - the most labour-consuming operation of repair also demands good knowledge, skills and skill.

The technology of repair develops of four stages: revealings of malfunction, definition of its character, elimination of malfunction, check after repair. To find malfunction - means, to find the given up, failed element, unit, the module, the block, the cascade. All can be divided malfunctions on mechanical and electric.

Ways of searching malfunctions:

1.External survey allows to reveal the majority of mechanical malfunctions, together with some electric. External survey it is possible to check up quality of assembly and installation. At quality check of assembly manually check mechanical fastening separate units. External survey check also quality of electric installation: reveal integrity of connecting conductors, absence ??????? solder which can lead to short circuits between separate sites of the scheme, find out wires with the broken isolation, check quality of soldering, and also presence of all elements according to the scheme. External survey supervise conformity of face values of components, reveal defects of separate elements (breakage of conclusions, surfaces of resistors, mechanical damages of ceramic condensers, etc.). External survey make, as a rule, at the disconnected feed. Thus it is necessary to watch, that in installation casual subjects which at inclusion of the device can cause short circuit have not got. External survey it is possible to reveal malfunction of variable resistors (on smoothness of a course of an axis), tuning condensers, etc. In the included condition it is possible to define an overheat of transformers, ????????????????? condensers, cases of transistors and ??. Smells can testify To presence of malfunctions in the scheme of the device from an overheat of components, change of tone of the sound fluctuations caused by work of units of the scheme which are absolutely not audible during work or have characteristic tone of sounding. Sometimes during external survey there are doubts in serviceability of components. In that case it is necessary ??????? an element and to check up its serviceability more carefully.

2. The way of intermediate measurements consists in consecutive check of passage of a signal from the block to the block (from the cascade to the cascade) before detection of a faulty site. The given way is applied, for example, in the amplifier, consisting of several cascades when on an output of the amplifier owing to malfunction in any cascade there is no signal. For revealing this cascade on an input of the amplifier from the generator submit a verifying signal and an oscillograph look through oscillograms on outputs of separate cascades. On an output faulty the signal is absent.

3. The way of exception consists in consecutive exception of serviceable cascades, units and blocks during search of malfunctions. So, if in a radio receiver there is no sound signal on an output malfunction can be as in high-frequency, and low-frequency parts. If to submit on an input of the amplifier of sound frequency a verifying signal and thus on an output the signal the amplifier is serviceable will be audible, it can be excluded from the further troubleshooting and to pass to check of a high-frequency part of the receiver.

4. Way of replacement of separate faulty elements, units or blocks on serviceable widely use at check and repair. For example, having replaced the block, the module on obviously serviceable, it is possible to be convinced of malfunction replaced.

5. The way of comparison consists in comparison of parameters of the faulty device with parameters of serviceable same type or mark.

Troubleshooting carry out by the certain rule (algorithm) allowing as much as possible to reduce time of search.

Element base 1

Resistors are the most widespread elements of the radio-electronic equipment. Constant resistors provide operating modes of intensifying devices, allow to extinguish surplus of a feeding pressure, a part of smoothing filters, are used in dividers of a pressure and as equivalent loadings. Variable resistors use in regulators of various sizes, tuning apply to installation of operating modes of the equipment during adjustment and adjustment. It is possible to carry breakage of conclusions to malfunctions of resistors; change of resistance; an overheat or transformation into coal a spending layer; breakdown of the resistor (infringement of an isolating covering) at excess of an admissible pressure; infringement of smoothness of a course and contact (in variable resistors); bad fixing of value of resistance (in tuning resistors). Malfunctions of resistors can be revealed visually or by means of an ohmmeter. It is necessary to replace the faulty resistor. The special attention should be given capacities of dispersion of resistors. It is supposed to establish the resistor with greater capacity, but not on the contrary. At work in a pulse mode average capacity should not exceed nominal since through the resistor periodic impulses of a current which instant values can exceed considerably values in a continuous mode proceed.

Element base 2

Condensers are a part of oscillatory circuits, strip filters, are used as dividing and blocking, elements of communication, stores of electric charges, in smoothing filters, for temperature indemnification, for suppression of a radio noise, etc. To principal causes of failures of condensers of constant capacity it is possible to carry mechanical damages; breakage of conclusions; breakdown insulator; change of capacity; increase of losses; change of an insulance. Tuning and variable condensers can have such failures: short circuit between facings; bad fixing of value of capacity at its installation; mechanical damages. Failures of condensers can be revealed by visual inspection and probing devices. The elementary failures define by means of an ohmmeter. Features of application of condensers: - At work with high-voltage condensers it is necessary to consider the phenomenon of absorption of electric charges in insulator, (from 3 up to 5 %) at the fast category of the condenser on loading - it is dangerous energy causing incomplete kickback to a life. - at some mica and ceramic condensers "blinking" - spontaneous spasmodic change of capacity can take place. - at electrolyte condensers significant drop of resistance of escape leads to infringement of a mode of behavior of transistors and microcircuits. Complexity of detection of the depressed resistance of escape consists that it can be shown energized at the working device. - drop of capacity of condensers in smoothing filters leads to increase in pulsations of the straightened pressure. - at a choice electrolyte the condenser except for nominal capacity, it is necessary to consider an operating voltage, the current of escape should not exceed 0.1 mA on 1 mF. Submission of a pressure of return polarity is inadmissible.

Element base 3

Switching products are intended for necessary switchings in electric circuits of a radio set (switches, switches, the relay, plug sockets, pads, etc.). The reasons of failures of switching products can be mechanical damages of contact pieces, pollution of electric contacts, failure of mechanical devices (the springs, separate details), a voltage failure of an insulation substance of the switch, short circuit between contact groups, jamming of mechanical parts as a result of their deterioration. To define failures it is possible visually or an ohmmeter.

Element base 4

Diodes apply to straightening alternate currents, detecting of the modulated fluctuations, restriction of amplitudes of signals, maintenance of temperature indemnification of position of a working point (mode of behavior) of transistors, for an outcome in logic circuits. Failures of semiconductor of diodes can be revealed visually or by means of an ohmmeter. At check by an ohmmeter in direct inclusion resistance of transition should be less than tens Ohm, at return inclusion - more than hundred Ohm.

Element base 5

Stabilitrons are intended for stabilization of a pressure. As a matter of fact it is the semiconductor diode, the pressure on which in the field of a voltage failure at return offset poorly depends on a current in the set range. The control of stabilitrons displaced in a forward direction is carried out by check of resistance, as well as at diodes. At the control of stabilitrons without not dismantled the pressure between the anode and the cathode which should be equal to a pressure of stabilization of a stabilitron is measured. If the pressure is equal to zero the stabilitron short circuit (is punched) if the pressure is much more, than a pressure of stabilization in a stabilitron there is a breakage.

Element base 6

Transistors are active (intensifying) devices. Detectings, generating, transformations of electric signals are used for strengthening, and also for restriction of amplitudes and in schemes of switching, etc. the Reasons of failures of transistors can be breakages of conclusions; interelectrode short circuits; an overheat and collapse of transitions; increase of a return current of transition; mechanical damages (cracking and deformation of the case). Failures define by means of probing devices - testers or special devices for measurement of parameters.

Element base 7

Integrated microcircuits are very widely used in cellular telephones. They represent the microelectronic devices containing diodes, transistors, resistors and carrying out the certain function (for example, the booster of capacity of sound frequency). At operation of microcircuits it is necessary to observe strictly polarity of feeding pressure. The reasons of their failure can be breakages of conclusions; interelectrode short circuits; an overheat and collapse of transitions; mechanical damages (cracking and deformation of the case, hit of a flux between conclusions and the case of the integrated microcircuit, leading gradual refusals, etc.) . At search of failure in the beginning supervise a mode of behavior of an integrated microcircuit on a direct current. The underestimated pressure on one of conclusions of an integrated microcircuit can be because of presence of escape of the condenser connected to this point which at check can be disconnected. Working capacity of an integrated microcircuit can be checked up and in a dynamic mode, by means of an oscillograph, supervising passage of the signals generated and brought on its inputs. At check of an integrated microcircuit it is necessary to be convinced, that its output is not shunted by the subsequent cascade. For this purpose it is possible to cut a printed path.

Common Faults In Mobile Phones:

First of all we will discuss how many main functions a mobile phone often has irrespectively of mobile brands.

A typical mobile phone has various types of faults which can be distributed in two main kinds of faults:

Hardware faults
Software faults
Setting Faults

Hardware Faults:

Hardware faults in mobile phones are related to mother boards of mobile phone, batteries and any physical fault will be amount to hardware faults. I have pointed out as much hardware faults as much i remeber this time but if you have a fault which is not listed below you can tell me by clicking here I willo be glad to know that it would be a great help for me too.The list of common hardware faults is given below.

* dead set condition
* no charging
* battery empty
* auto charging
* low signal
* No signal
* voice problem
* vibrator problem
* ringer problem
* backlight problem
* auto turn off
* hanging problem
* insert sim (no sim card inserted shows on the screen)
* keypad problem
* display problem
* Software faults
* no signal
* dead set
* display
* contact service (contact retailer, contact service provider)
* Test mode
* not charging
* Setting problem:
* call divert
* sim lock
* security code
* country lock
* cnfiguration of SMS
* configuration of GPRS
* configuration of call

Dead Set Repairing:

We are going to discuss here some techniques and steps to repair dead condition in mobile phones irrespectively of brands in a primary way.


Key Components and functions:

* Battery
* Power Switch
* battery terminal
* Power IC
* Oscillator
* Frequency divider
* CPU
* Flash (ROM / EEPROM)

Battery:

A battery is used to provide power supply to our mother board unit so if this battery or on of its functions fails the whole mobile phone fails to power on. So battery must be in good condition to make a mobile phone power on. Some times the third Pin used in battery which is called "BSI" is not working correctly but voltage can be found in " + " and " - " terminals, in this situation mobile phone cannot turn on.

Power Switch:

A power switch is used in a mobile phone to turn on and off mobile phones if it is faulty the whole unit cannot power on so keep checking its terminals whether they are connected with the power IC of not if not then you can make a jumper and connect it.

Battery terminal:

battery terminals connect battery to mobile phone component unit if its points are dry soldered of unsoldered or bended then you can change and fix this problem which is always in the result of no power on. so if battery terminals are working correctly you need to proceed further.

Power IC:

A power IC distributes current among all the components actually a power IC works as " voltage regulator" and " power on function" so if a power on function is faulty the whole unit will not power on. but there are some problems with ICs that we cannot check them whether they are working right or not rather we can only assume that they are faulty if the other functions are correct.

Oscillator:

An oscillator makes low frequency which is called clock frequency. this frequency is used to run digital components if this frequency is not available digital components fail to work and the result is power on failure. the out put frequency is used in mobile phone's CPU and Memory chips and UEM Ic if used.

Frequency divider:

Frequency dividing is a function which is used in mobile phones to divide clocked frequency to get accurate frequency to run digital components so if divider is failed power on fault mat occur. this frequency dividing function is built in radio ICs commonly like hagar IC or Mojoelner in Nokia mobile phones.

CPU:

A CPU (central processing unit) is like a brain in mobile phones which controls the major parts of mobile phones so its functionality is very necessary in mobile phones while testing in boot process but its functionality is associated with Memory chips used in mobile phone specially Flash chip.

Flash Chip ( EEPROM)

A flash chip holds booting information in it self it has instructions stored in itself for the CPU to control other components so if flash chip or its software is damaged it mean the set do not power on. in case of damaged software the phone should be treated in flashing process.

* The word flashing denotes in mobile phones that some software installation.

Steps in Repairing Dead Sets:




Note: Some steps which cannot be take in an average mobile phone lab are avoided to be explained because oscillator and divider's functionality can be checked by Oscilloscope which is not available in an common mobile phone lab.

How a mobile phone powers on:


First of all look at the picture below carefully. This picture describe booting detail about NOKIA mobile phones but same structure can be applied to the other brands with a little modification.




In the picture above all of you can see a little block diagram illustrating mobile phone booting sequence. first of all I am starting explanation from power switch.

When a power switch is pressed it turns on a circuit inside the power IC and this IC starts distributing power supply to other parts of mobile phones. On the first place VCO( voltage controlled oscillator) or an other type of clock oscillator starts producing a clock frequency of 26MHz in some mobile phones this clock frequency is directly used to run CPU but most of the sets in NOKIA brands it is distributed bye hagar IC or RF Signal processor and it becomes 13MHz in the end of the division process. this low frequency clock signal is used to start CPU functions now CPU which is like the brain of the mobile phone comes to the senses and first of all contacts its memory to know what are the instructions written it for this event and its memory tells CPU that if you feel that you are finding 13 MHz from hagar IC you have to run a booting test. in this test CPU tests most of the mobile phones function if they are correct CPU will order power IC to continue providing power to other parts and CPU also starts its display section. so this is the total process in which a mobile phone comes to the power on state.

Responsible parts for mobile phone power failure there are eight elements which can affect mobile phone power on function:

* Power Swicth
* Battery
* Battery terminal
* power supply tracks
* power IC
* Ocsilator (VCO)
* hagar IC
* flash (programming)

So we can say that when ever a mobile phone fails to power on there may be a fault in such type of parts which are used in mobile phone booting process.

How to handle water damage phones:

Ever dropped your cell phone in the sink,? Did you ever leave it in your pocket and run it through the washer? It usually means you have to replace your phone, but sometimes if you're fast you can save the phone.

1. Remove the Battery. This is one of the most important steps. Don't take time to think about it, electricity and water do not mix. Cutting power to your phone is a crucial first step in saving it.

2. Dry your Phone. Obviously you need to remove as much of the water as soon as you can to prevent it from getting into the phone. Use a towel or a paper towel to remove as much of the water as possible.

3. Soak in Alcohol. Alcohol is hygroscopic (attracts water), it will dissolve all the water in the phone, which will then pour out of the phone with the alcohol. Any remaining alcohol will evaporate. Alcohol will not harm your phone but may mess up glue (from stickers and the like). Use 95% alcohol, not the regular 70% rubbing type. Do it outside!. If you use alcohol, do not follow the rest of the advice here, instead leave your phone outside for a day or two to dry.

4. Allow the phone to dry. Since you do not want to ruin your phone or lose all the numbers in your phone book, you need to allow the phone to dry. Don't try putting the battery back on to see if it works as this would risk damaging the phone with a short circuit. Leaving your phone in a bowl of dry rice will help to expedite moisture evaporation.

5. Heat your Phone. Apply enough heat to your phone to cause the water to evaporate without water logging your digital screen. One of the best things you can do to save a cell phone is to set it on the back of your computer monitor or TV screen over the heat vents. This is usually the perfect amount of heat to fix your phone. The convection action of the heat vents will help carry away the moisture in your phone. Leave the phone on the heat for at least 2-3 days. Another option is to leave it overnight in the oven on warm (make sure to take off the battery first).

6. Test your Phone. After you have waited 3 days, make sure everything is clean and dry looking and re-attach the battery to the phone and see if it works. If your phone does not work repeat step 4. If it still won't work, try taking your cell phone to an authorized dealer. Sometimes they can fix it.

Tips :

* Don't put the battery on for at least 3 days or longer if your digital screen is foggy.

* Place a piece of satin finish scotch tape over your water damage sticker before you drop your cell phone in the water to prevent the water damage sticker from voiding your warranty. This sticker can usually be found under your battery. It's a small round white sticker, possibly with dots on it. If this sticker gets wet it changes color and your phone is marked for water damage.

* Remove the tape if you ever have to return your phone for repairs or warranty. (See the note in the 'Warnings' section about doing this!)

* The best way to dry out your phone is to place it in front of an air conditioner or air conditioning vent. Cold air won't damage your phone (hot air can warp or in extreme cases even melt plastic), and air from an air conditioner is dry, and so will evaporate water faster than you might think (which is why a car air conditioner will de-mist the windshield so effectively, even if the engine hasn't warmed up yet). Warm air from a reverse-cycle air conditioner works even better, of course. If you dry your phone in this way overnight it should be fine by the morning.

* Use a hairdryer set on warm; it won't melt your head so your phone should be safe.
* Use a food dehydrator.
* Use the oven on the warm setting (make sure to take out the battery).

Warnings:

* Don't heat the battery or it could leak acid. If you use an oven or hairdryer, make sure to remove the battery first.

* If you use alcohol make sure to do so outside, and do not apply heat in any form, not even the gentle heat of a monitor. Do not hook up the battery till the alcohol smell dissipates.

* Do not apply heat to your phone other than mentioned above. You don't want to melt or burn your phone.

* Warranty fraud is naughty! If you dropped your phone in the can with your other 'droppings'--are you really going to send it in for a warranty tech to have to open? Yuck!

* FYI, Most modern phones have more than one liquid damage indicator on them, only one visible to you (and sales/technician agents), and chances are, if the sticker under the battery is triggered (or would be, with the scotch tape trick), then the odds are that the internal stickers you can't access are tripped as well. This will still result in you paying a voided-warranty fee in the long run, and it may be best to just learn from your mistake (and not make it more financially severe!).

* Even if all these steps are followed, minerals dissolved in the water can precipitate on solder and component pins, causing corrosion or shorting. Components pins are packed so closely together in a modern cell phone that even a small encrustation can create a short, rendering the phone inoperable.

Charging Faults

First of all we will discuss how many main functions a mobile phone often has irrespectively of mobile brands.

Charging faults are mainly of three types:

* No charging
* Not charging
* Auto charging

No charging:

in this fault a mobile phone does not charge at all when charging pin is inserted nothing happens it is always due to damaged fuse. For broken charging supply track if we repair fuse or jumper broken tracks we can set this fault off.

but on the first step I am telling you how to check no charging fault.

Check Your battery if it is not connected properly no charging fault occurs. check continuity between charging pins it should be nor full nor high resistance. If it is showing full continuity then there may be some problem in your charging IC may it is totally short you can re hot /replace this IC. If there is no continuity in charging pins 90% fuse is damaged. You can replace fuse or jumper it. if a fuse shows full continuity in multi meter then it is working correctly if it is not so it is damaged. If fuse is not damaged you can check tracks if broken. if fuse, battery and tracks are ok then charging IC would be damaged.


Not charging:

in this fault a mobile phone shows a message "Not charging" on the screen when ever it is connected with charging pins. this type of fault is not a mere hardware fault it is 90% software fault. this fault is present only in nokia and I personally experienced a problem with a nokia 3100 it was showing "Not charging" i tried hardware solutions but totally in vain so I upgraded my software now every thing was ok. . and this is the same case in many types of nokia brands you can check this up. Only nokia 1100 when "Not charging" fault comes it is very hard to remove this fault in nokia 1100 I only repaired a little number of nokia 1100 displaying this message there was a problem in charge connector diode next to charging fuse. but often it can be solved by repairing software or upgrading it.

Auto Charging:

In auto charging a phone continues showing charging despite of removing charging pin from phone. In this type of fault the "BSI" pin of mobile phone is very important because it is used to tell the phone what is the state of mobile phone charging now so if this pin is not ok this fault occurs. There are some cases in wich a mobile phone battery is ok but auto charging is present you can check transistors if used in charging section and if faulty replace it because this transistor is used in some mobile phones to cut off charging from phone automatically. in In some cases a resistance in charging section is responsible for that which is marked as "R22" in charging section so you can check "+" supply connection with this.

Signal Problem

No signal:

Now we are going to discuss here some important causes of no signal. if you find a handset with no signal inside it you can consider these components likely to be damaged.

* Antenna
* Antenna pad
* Antenna switch
* antenna tracks
* Rx filters
* Rf Power Amlifier
* or tracks
* Rf signal processor (called hagar IC in nokia)

Some time you can experience that signal fault is due to damaged antenna, so you need to replace this antenna specially in SonyEricson the antenna is sticker type and it can be easily damaged so you consider first antenna in mobile phone signal faults.

Antenna pad is often rusted with corbon so you can wash it with cleaner like CTC (carbon tetra chloride) this place is often responsible for low signal faults.

!Antenna switch is the component which is most common in mobile phone signal faults you can locate this component on the top of the mother board it is in steel case often. purpose of this component is to switch between two or some time three type of frequency bands which are (GSM 900MHz , EGSM 1800MHz, PCS 1900MHz ) you may know that there are two types of waves used in our radio section one is TX (which is transmitted to others) second is R which we receive from others) antenna switch connects GSM Rx and GSM Tx with antenna pin when it found in GSM based network and in the contrary situation it contacts DCS Rx and DCS Tx pin with antenna pin so may both signal can be communicated.

Antenna tracks are the other reason to no signal so if the contacts between antenna and antenna switch are broken there would be no signal at all.

RX Filters are used to filter incoming radio waves so may no harmonics and other frequencies could get into signal processing only targeted frequency can be enter into the specific place, so some times our RX filters filter frequency we needed as well as other frequencies you can say that they block our target frequency so we can replace these filters to get it repaired. this is not in common cases but we found many faults like this in nokia 8210 no signal problem. The basic thing about radio frequency Power Amplifier is that when we need strong radio waves to spread far around then we have to use some type of amplifier which will be able to amplify radio waves in a good power so our mobile phone uses PA(Rf power amplifier) it is used to communicate between long distances like 15-to-20 kilometers so if our PA is damaged it can not communicate and get response from the base stations.

If the supply of PA is disconnected it cannot work so signal faults can occur so you should check PA +supply carefully. The main head of the radio department in mobile phone is Rf signal processor which is often used to create, measure, calibrate and manage radio waves so if there is a problem in this signal processor you can say that there will be no signal at all, in some sets you can check they cannot be turned on without radio IC( rf signal processor) like in all nokia mobile phone you cannot power on a set without radio IC except special circumstances.

How to repair Signal problem?

Here we are discussing the techniques to repair signal faults in mobile phone first of all we are discussing about no signal condition.

Common reasons of No signal:

* antenna is not connected to phone either contacts or tracks are open
* antenna switch is not switching for rf signals
* some mutual coupler may be damaged
* RF filters may be damaged
* RF signal processor is not working
* RF signal generator (VCO) is not working
* software problem

Steps to be taken:

Check if antenna is properly conected to antenna pad if not then you can clean it and adjust it with pad if it is not possible then some technicians use jumper to connect antenna with antenna pad. in condition of open track between antenna switch or duplexer and antenna you can check continuity between antenna and antenna pin of antenna switch, if track is broken you can make a jumper at this place to fix this problem. Most often you may come to know that in signal problems there are lot of sets which have faulty antenna switch. so you can check it by removing antenna switch and making a jumper between RX & TX and antenna pin. It is very rare that you may come to know that the phone you are repairing has a damaged mutual coupler you can just check mutual by checking continuity between four pins in one side and of four pins in the other side but it is very rare to find a damaged mutual coupler but the chances still exist. RF filters a also very rare to find in no signal problem in mobile phones but you can't ignore this because in NOKIA 8210 there were mostly found damaged filters in signal faults. Rf signal processor is the main component which controls the whole Rf section if the above steps fail to power on signals in mobile phones then you can consider Rf signal processor responsible for that fault, first you should know that in NOKIA & SonyEricson you can find RF signal processors in the form of BGA IC (which has terminals below its body) but in Samsung it is mostly in the form of SMT IC ( which has its terminals at the four sides of its body) remember some time BGA ICs are suffered of dry soldering so if you find you RF signal processor in BGA form you can first check it by making reheat it and if the problem exists you can replace this IC. note ICs and IC type components has no verified checking method. so you can take a chance to replace this IC if you found problem after taking the steps mentioned above. In some mobile phones rf signal generators is used to produce a signal which is often mixed with RX received from antenna and then there is some processing on the mixed form of rf signal so if RF signal generators which are mostly known as VCO (voltage controlled oscillator) is corrupt no signal faults may occur. In the final I am going to tell you about the software function used in mobile phones your mobile phone uses its software to connect to the network and to set frequencies in mobile phones and there are some instructions found about controlling the hardware RF section by CPU with the help of software, so if the software of your mobile phone is corrupted then you may have signal faults in your mobile phone. you can see the example of all NOKIA DCT3 models if there is no "set FAID" option is checked while flashing mobile phone the phone after flashing does not show signals so don't ignore software problems in no signal. When signal comes and then disappears. If you find a problem in some mobile phones that when mobile phone is turned on it shows signals for a while and then signal disappears after some seconds you can consider your Rf power amplifier is faulty or unsoldered or dry soldered. Explanation when we turn on the phone it shows the signal strength bars because it is receiving signals from the base station and then our phone tries to send its information about its serial number and SIM identification number to the base station and you can think that whenever phone tries to send signals to the other device it uses Rf Power amplifier (PA) and if the PA is not supporting the phone to send the informations to the base station then our phone disconnects its half way link to base station and stops displaying signals.

How to repair this problem?

First check the supply connection with your PA if supply is broken then you can make a jumper at this point check Tx signal tracks going to the PA from RF signal processor if broken then jumper it check Tx signal tracks going from PA to antenna switch if broken then jumper it. Reheat your PA. remove PA and then place two jumpers in rf in and out points at the place of PA replace PA it will be 100% right in working now.


Ringer / Buzzer Faults:

Lets see how to repair / service ringer problem!

First of all check the settings of the phone for ringer & see whether it is on or off!

Then disassemble phone & check the ringer value using multimeter on resistance mode [ see multimeter section].

The correct value of ringer should be as shown below:

monophonic ringer --- 15-19 ohms
monophonic ringer examples, nokia 3310, 3210, 2100, etc.

Polyphonic ringer------ 7-8 ohms
polyphonic ringer like nokia 6600, 6610, sonyericsson t610, etc...



This ringers always should give buzzer while checking with multimeter on a continuity mode as they all are low value resistance ..
All midi, wav , mp3 , supported phones are polyphonic ringer phones & all monophonic rings supported phones are those who do not support such ringtones.

Vibrator Problem:

Same as ringer, vibrators are also low resistance. So all vibrators will also give buzzer on multimeter while checked on continuity[buzzer] mode. mostly vibrators are showing 12-18 ohms value.



Speaker Problems:

Speakers also shows low resistance value , hence checking two connectors with multimeter on a buzzer mode will give buzzer.
The correct value of speaker without buzzers always are nearly 30 ohms like nokia 3100, nokia 3315, nokia 6600 etc.
The speaker & ringer combined will show value around 7-8 ohms only like Samsung c100.



Mic Problems:

The Mic in mobiles are used to send voice , & if it damages the receiver will not be able to hear voice. To check mic you have to select multimeter in diode mode & it shows value at one end, & will not show value on multimeter if the multimeter leads are interchanged. Mic will never give buzzer unlike speakers & vibrators if set to buzzer mode on multimeter.

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Basic GSM abbreviations
________________________________________


AAL - ATM Adaptation Layer

A-bis = Interface between the BSC and BTS in a GSM network
AB - Access Burst
used for random access and characterised by a longer guard period to allow for burst transmission from a MS that does not know the correct timing advance when first contacting a network

ABR - Available Bit Rate

AC - Alternating Current ( the standard electricity type )
ACCH - Analog Control Channel
ACTS - Advanced Communications Technologies and Services.
a European technology initiative
ACU - Antenna Combining Unit

AC Charger :

an accessory device that allows you to power and/or charge your phone from a wall outlet

ADC - Analog to Digital Converter

Advice of charge:
A service which provides the user with information on the cost of calls from a mobile phone

AFC - Automatic Frequency Control

AGC - Automatic Gain Control

AGCH - Access Grant Channel; downlink only, BTS allocates a TCH or SDCCH to the MS, allowing it access to the network

A-interface :
Interface between the MSC and BSS in a GSM network


AM - Amplitude Modulation

AMPS - Advanced Mobile Phone Service

Advanced Mobile Phone System (AMPS) is the analog mobile phone system standard developed by Bell Labs, and officially introduced in the Americas in 1983[1][2] It was the primary analog mobile phone system in North America (and other locales) through the 1980s and into the 2000s, and is still widely available today, although use has dropped considerably with the introduction of various digital standards.

Total Access Communication System (TACS) and ETACS are mostly-obsolete variants of AMPS which were used in some European countries (including the UK). TACS was also used in Japan under the name Japanese Total Access Communication (JTAC).[3][4]


AMR - Adaptive Multi-Rate codec.

Developed in 1999 for use in GSM networks, the AMRhas been adopted by 3GPP for 3G

Analogue:
The representation of information by a continuously variable physical quantity such as voltage


Antenna:
a part of a cell phone that receives and transmits cellular radio-frequency transmissions


ASCII
American Standard Code for Information Interchange

ASIC - Application Specific Integrated Circuit

Electronic chips designed for some concrete purposes (for example, in phone it controlls communication between MCU and DSP) They're designed and produced by the companies which use them.

ATM
Asynchronous Transfer Mode; a multiplexed information transfer and switching method in which the data is organised into fixed length 53-octet cells and transmitted according to each application’s instantaneous need

AVCH - Analog Voice Channel

BB5 - base band 5

BCC - Base-station Color Code

B-CDMA - Broadband Code Division Multiple Access

BCH - Broadcast Channels( carry only downlink information and are mainly responsible for synchronisation and frequency correction (BCCH, FCCH and SCH)

BCCH - Brodcast Control Channel
the logical channel used in cellular networks to broadcast signalling and control information to all mobile phones within the network

BGA - ball grid array

B-ISDN - Broadband ISDN

BPS - Bits Per Second
( a measure of how fast binary digits can be sent through a channel. The number of 0s and 1s that travel down the channel per second.)

Base transceiver Station Identity Code

BTS - Base Transceiver Station
(This device allows communication between phones and cellular network or it is the network entity which communicates with the mobile station)

Back -light Illumination
illuminates a wireless device’s display and keypad for better low light viewing
Band :
a specific range of frequencies in the radio frequency (RF) spectrum.

Battery:
A chargeable device which provides the mobile phone with power. A variety of battery technologies have been used for mobile phones including nickel cadmiu(NiCad),nickel metal hydride (NiMH) and lithium ion (Li-ion)
Battery status/Battery charge display
An indication of the amount of battery life remaining
Battery Capacity the capacity of wireless devices’ battery. Measured in milliampere hours (mAh).

Call barring
A service which enables users to bar certain incoming or outgoing calls on their mobile phones

Call timer:
A service which keeps track of the amount of airtime being used by the subscriber on a cumulative basis

Call divert:
The capability to divert incoming calls to another phone (fixed or mobile) or to an answering service

Call hold:
The ability to put an ongoing call on hold whilst answering or making a second call

Caller ID:
Caller Identification (displays the name/number of the person calling a mobile phone. Also known as CLI)

CB - Cell Broadcast

CCCH - Common Control Channels; a group of uplink and downlink channels between the MS and the BTS (see PCH, AGCH and RACH)

CCONT- Current Controller (in nokia fones)

CDMA - Code Division Multiple Access
(Code Division Multiple Access; also known as spread spectrum (or IS-95), CDMA cellular systems utilise a single frequency band for all traffic, differentiating the individual transmissions by assigning them unique codes before transmission. There are a number of variants of CDMA (see W-CDMA, B-CDMA, TD-SCDMA et al)

Cell:
The area covered by a cellular base station. A cell site may sectorise its antennas to service several cells from one locationCell site
The facility housing the transmitters/receivers, the antennas and associated equipment


Cell Site:
a fixed cellular tower and radio antenna that handles communication with subscribers in a particular area or cell. A cellular network is made up of many cell sites, all connected back to the wired phone system.

CF - Call Forwarding

CI - Carrier to Interference ratio

CID - Caller Identification

Circuit switching:

A method used in telecommunications where a temporary dedicated circuit of constant bandwidth is established between two distant endpoints in a network. Mainly used for voice traffic; the opposite of packet switching


CNT- Content



COBBA- Common Baseband Analog

CPU - Central Processing Unit

CMOS - Complementary Metal Oxide Substrate


Codec:
A word formed by combining coder and decoder the codec is a device which encodes and decodes signals. The voice codec in a cellular network converts voice signals into and back from bit strings. In GSM networks, in addition to the standard voice codec, it is possible to implement Half Rate (HR) codecs and Enhanced Full Rate (EFR) codecs

Control signal:
A signal sent to a cellular phone from a base station or vice versa which carries information essential to the call but not including the audio portion of a conversation

CRC - Cyclic Redundancy Check

CT - Cordless Telephony

CTA - Cordless Terminal Adaptor (a DECT term)

CTM - Cordless Terminal Mobility

CTR - Common Technical Regulation

CUG - Closed User Group

D/A - Digital to Analogue conversion

DAC - Digital to Analogue Convertor

D-AMPS - Digital AMPS, a US wireless standard also known as IS-136



Data capable:
Mobile phones which have the capability to enable transmission of data from a laptop computer or PDA via the phone

Datacable : interface for conecting a mobile fone to pc

db - decibel (unit if sound)

DCT /3,4 - digital core technology

DCT/L - digital core technology linda

DCCH - Digital Control Channel
DTCH - Digital Traffic Channel
DTX - Discontinous Transmission Exchange

DCA - Dynamic Channel Assignment

DCCH - Dedicated Control Channels
( responsible for roaming, handovers, encryption etc)

DCE - Data Communications Equipment

DCH - Data Clearing House

DCS1800 - Digital Cellular System at 1800MHz, now known as GSM1800

Digital:
a method of representing information as numbers with discrete values; usually expressed as a sequence of bits
Digital a method of encoding a transmission that involves translating information (in the case of digital phones the information would be a voice conversation) into a series of 0’s and 1’s. Digital communications technology offers cleaner calls without the static and distortion that is common with analog phones. The majority of new handsets sold today are digital rather than analog technology.


DSP - Digital Signal Processor
Digital Signal Processing refers to manipulating analog information, such as sound or photographs that has been converted into a digital form to improve accuracy and reliability of digital communications.


DSC- Digital Signal Controller

DTE - Data Terminal Equipment

DTMF - Dual Tone MultiFrequency;
(better know as Touch Tone. The tones generated by touching the keys on the phone are used for a variety of purposes )

DTX - Discontinuous Transmission

Dual Band:
The capability of GSM infrastructure elements and handsets to work across both the 900MHz and 1800MHz bands. The capability to seamlessly handover between the two bands offers operators major capacity gains

Duplex:
The wireless technique where one frequency band is used for traffic from the network to the subscriber (the downlink) and another, widely separated, band is used for traffic from the subscriber to the network (the uplink)


EEPROM - Electrically Erasable Programmable Read Only Memory

EFR- Enhanced Full Rate
(Enhanced Full Rate (codec): an improved version of the standard voice codec used in GSM phones; offers improved speech quality without impacting on network capacity)

EFT - Electronic Funds Transfer

EGSM - Extended (frequency range) GSM

EIR - Equipment Identity Register (a database that contains a list of all valid mobile stations within a network based on their IMEI)

EIRP - Effective Isotropic Radiated Power

EPOC :
The mobile phone operating system developed by Symbian. Derived from epoch-the beginning of an era-EPOC is a 32-bit operating environment which comprises a suite of applications, customisable user interfaces, connectivity options and a range of development tools

EPROM - Erasable Programmable Read Only Memory

ESMR - Enhanced Special Mobile Radio; a US PMR variant (see SMR)

ESN - Electronic Serial Number; a 32-bit number that uniquely identifies a mobile phone


FB - Frequency Correction Burst; used for frequency synchronisation of the mobile

FDD - Frequency Division Duplex

FOMA - Freedom Of Mobile multimedia Access

Gbit/s:
A unit of data transmission rate equal to one billion bits per second

GMSC - Gateway Mobile Services Switching Centre; the gateway between two networks

GCF - Global Certification Forum

Geostationary:
Refers to a satellite in equatorial orbit above the earth which appears from the surface to be stationary

GERAN - GSM-EDGE Radio Access Network the name for the evolution of GSM towards 3G based on EDGE

GGRF - GSM Global Roaming Forum

GGSN - Gateway GPRS Support Node; the gateway between a cellular network and a IP network.

GHz:
A unit of frequency equal to one billion Hertz per second

GMPCS - Global Mobile Personal Communications by Satellite

GMSK - Gaussian filtered Minimum Shift Keying

GPRS:
General Packet Radio Service (GPRS) is a mobile data service available to users of GSM and IS-136 mobile phones. GPRS data transfer is typically charged per megabyte of transferred data, while data communication via traditional circuit switching is billed per minute of connection time, independently of if the user actually has transferred data or been in an idle state. GPRS can be utilized for services such as WAP access, SMS and MMS, but also for Internet communication services such as email and web access. In the future, it is expected that low cost voice over IP will be made available in cell phones.



GPS:
The Global Positioning System (GPS), is currently the only fully-functional satellite navigation system. More than two dozen GPS satellites are in medium Earth orbit, transmitting signals allowing GPS receivers to determine the receiver's location, speed and direction.



GRX - GPRS Roaming Exchange

GSM

The Global System for Mobile Communications, GSM (original acronym: Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. GSM service is used by over 2 billion people across more than 212 countries and territories.[1][2] The ubiquity of the GSM standard makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs significantly from its predecessors in that both signaling and speech channels are Digital call quality, which means that it is considered a second generation (2G) mobile phone system. This fact has also meant that data communication was built into the system from the 3rd Generation Partnership Project (3GPP).


Hands-free:
The operation of a cellular phone without using the handset; usually installed in vehicles.

Handoff:
The transfer of control of a cellular phone call in progress from one cell to another, without any discontinuity


HR - Half Rate Traffic


IC - Intergrated Circuit

ICSP - In Circuit Serial Programming

IF- Intermediate Frequency

Infrared data port:
A facility on a mobile phone to allow information to be exchanged with other devices e.g. a PC using infra red technology

Internet
The Internet is the worldwide, publicly accessible network of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP). It is a "network of networks" that consists of millions of smaller domestic, academic, business, and government networks, which together carry various information and services, such as electronic mail, online chat, file transfer, and the interlinked Web pages and other documents of the World Wide Web.



IMEI - International Mobile Equipment Identity
The International Mobile Equipment Identity (IMEI) is a number unique to every GSM and UMTS mobile phone. It is usually found printed on the phone underneath the battery and can also be found by dialing the sequence *#06# into the phone.

The IMEI number is used by the GSM network to identify valid devices and therefore can be used to stop a stolen phone from accessing the network. For example, if a mobile phone is stolen, the owner can call his or her network provider and instruct them to "ban" the phone using its IMEI number. This renders the phone useless, regardless of whether the phone's SIM is changed.



I-mode:
A service developed by Japanese operator NTT DoCoMo, I-mode delivers a huge range of services to subscribers and has proved enormously popular with some 30 million regular users. The revenue sharing model used for I-mode is being adopted by other operators as the basis for the new services enabled by GPRS and 3G



IMSI - International Mobile Subscriber Identity
(an internal subscriber identity used only by the network)


IP - Internet Protocol


IrDA - Infra red Data Association

Iridium:
A low earth orbit satellite communications system developed initially by Motorola.

ISDN - Integrated Services Digital Network

ISO
International Standards Organisation

ISP - Internet Service Provider

iTAP:
software developed by Motorola and built into some wireless phones and PDAs that makes typing words on a keypad easier. The competitor to iTAP is T9

JAF - Just Another Flasher

Java:
A programming language developed by Sun Microsystems Java is characterised by the fact that programs written in Java do not rely on an operating system

JPEG- Joint Photographic Experts Group

JTAG - Joint Test Action Group

Kbps : Kilobits Per Second, a measure of bandwidth


LAN
Local Area Network

LANS
Local Area Network Services

LED - Light Emitting Diode
(a semiconductor device that illuminates when electricity passes through it. Often used as an indicator light, or to spell out words and numbers. LEDs come in many colors, and some LEDs contain multiple elements and are therefore capable of multiple colors. Provides good visibility in direct sunlight and in darkness)


LPT - Line Print Terminal

LMSS
Land Mobile Satellite Service

Lock
A function on a cellular phone which, when activated, prevents use of the phone until the user enters a security code

LCD - Liquid crystal display



Lithium Ion battery:
a type of rechargeable battery for cell phones which is generally lighter weight than earlier battery types, has a relatively longer cycle life, and generally does not suffer from “memory” effect.

MAC - Media Access Control; the lower sublayer of the OSI system

MAD - Memory Analog Digital

MAP - Mobile Application Part

Mb- Megabite
( a unit of data transmission speed equal to one million bits per second)


MCC - Mobile Country Code

MCU - Micro Control Unit

MCPA - Multi Carrier Power Amplifier

MHz - Megahertz (a unit of frequency equal to one million Hertz)

MMI - Man Machine Interface

MMS - Multimedia Messaging Service
(an evolution of SMS, MMS goes beyond text messaging offering various kinds of multimedia content including images, audio and video clips)

Modulation:
The process of imposing an information signal on a carrier. This can be done by changing the amplitude (AM), the frequency (FM) or the phase, or any combination of these

MPEG:
Motion Picture Experts Group; MPEG4 is a technology for compressing voice and video so that the information can be transmitted over normally difficult links such as mobile radio

MS - Mobile Station

MSIN - Mobile Station Identification Number

MSISDN - Mobile Station International ISDN Number

MSK - Minimum Shift Keying (Another term for FFSK)

Multiplexing:
A telecommunications technique where several channels can be combined to share the same transmission medium. The most common forms are Time Division Multiplexing (TDM) and Frequency Division Multiplexing (FDM)


Master Reset:
restores the setting to factory

MIDI - Musical Instrument Digital Interface
(a standard that allows digital musical instruments to communicate with one another. In cell phone terms, MIDI is what gives you polyphonic sounds; which means your ring tones can sound like real music instead of beeps. )

MMS - Multimedia Messaging Service
(a further extension of SMS and EMS.MMS is designed to make use of newer and quicker mobile transmission methods such as GPRS, HSCSD, EDGE and UMTS, involving the attachment of multimedia extensions to messages, such as video and sound. An e-mail function is also planned. )

MO-SMS - Mobile-Originated Short Message Service
(the ability to send short text messages from a phone. Both the phone and the carrier’s network must support this feature for it to work. Messages can be sent to other phones by phone number. Many phones also allow sending messages directly to e-mail addresses. )


NCC (National Color Code or Network Color Code

NET
Norme Europeenne de Telecommunications


NMSI - National Mobile Subscriber Identity

No Service:
An indication on the display of a cellular phone that indicates that the user is in an area where cellular service is unavailable


OMAP - Open Multimedia Applications Platform

OTP - One Time Programable


PCM
Pulse Code Modulation; the standard digital voice format at 64kbit/s

PCMCIA
Personal Computer Memory Card Interface Association the body responsible for defining

the standards and formats for memory expansion cards for laptop computers and PDAs. Now

extended to cover cards for mobile phones


PCU
Packet Control Unit; an element in a GPRS/UMTS network

PDA
Personal Digital Assistant


PIN
Personal Identifier Number


PSU
Power Supply Unit


PCN
Personal Communications Networks; an outdated term for GSM services in the 1800MHz band

PDA
Personal Digital Assistant; a sophisticated handheld device with advanced display

facilities and a range of business-oriented software programs

Phone book
A list of personal names and numbers stored in a mobile phone’s internal memory or in

the SIM card. These numbers can be called by accessing the appropriate memory and

making a single key stroke

PIN
Personal Identity Number; a number, usually four digits, that must be keyed into a

mobile phone to make it work. A security measure to prevent unauthorised usage

P-Java (Personal Java) a Java API and specification for running Java applications on

small devices.

Packet a piece of data transmitted over a packet-switching network such as the Internet

or wireless Internet; a packet includes not just data but also its destination.

Packet Switching a type of communication that splits information into “packets” of data

for transmission. This is efficient, as it only uses radio spectrum when it’s actually

sending something, rather than keeping an open channel at all times (as is done in

circuit switching). Packet switching is a core component to 3G technology.

Passive Matrix Display an LCD technology that uses a grid to supply the charge to each

particular pixel on the display. An STN screen has a slower refresh rate than a TFT

screen, but it’s cheaper. Also called a SuperTwist Nematic of STN display.

PC Card (PCMCIA) a removable, credit-card sized devices that may be plugged into slots

in PCS and wireless communication devices to provide fax or modem functions or network

cards.

PCMCIA (Personal Computer Memory Card International Association) a group of hardware

manufacturers and vendors responsible for developing standards for PC Cards (also

called PCMCIA cards.)

PCN:

also known as DCS 1800 or GSM 1800, PCN is a term used to describe a wireless

communication technology in Europe and Asia.

PDA (personal digital assistant) a portable, handheld computing device that acts as an

electronic organizer. PDAs are typically used for managing addresses, appointments,

to-do lists and notes, but some newer models support wireless Internet access, e-mail,

and other interactive applications. Also referred to as Handheld Computers. PDAs come

in two major flavors - Palm and Pocket PC.

PIN (Personal Identification Number) a numeric code or password that may be required by

a service provider in order to make outgoing calls or obtain access to certain

applications and data. This code is always associated to a SIM card, not a phone and is

designed to help guard against cellular fraud.

PTT (Push-To-Talk) a two-way communication service that works like a “walkie talkie”.

This feature, found on Motorola iDEN phones from Nextel and Telus Mobility’s Mike,

allow communication in only direction at a time unlike a cell phone that allows for

simultaneous conversations. New PTT systems are now being introduced that use VoIP

technology to provide PTT service digitally over 3G data networks

PUK (Personal Unblocking Code) used to unblock a blocked SIM card, this code is given

during the sub******ion of a phone

PWR:
represents the on/off (power) key on some wireless devices.


RAM - Random Access Memory

RAP3G- Radio Application Processor 3rd Generations


Reuse:
The assignment of frequencies or channels to cells so that adjoining cells do not use the same frequencies and cause interference whereas more distant cells can use the same frequencies. Reuse expands the capacity of a cellular network by enabling the use of the same channels throughout the network


RF AMP = Radio Frequency Amplifier

RFP - Radio Fixed Part
(equivalent to a base station in a DECT system)

RP - Radio Part

Roaming:
A service unique to GSM which enables a subscriber to make and receive calls when outside the service area of his home network e.g. when travelling abroad

Router:
A device which forwards information in a network on a connectionless basis


RT - Remote Terminal

RX :- signal received



SAR - Specific Absorption Rate


S-CDMA - Synchronous CDMA (see CDMA)

SCH - Synchronisation Channel
(downlink only frame synchronisation and identification of base station)

SCP - Switching/Service Control Point

SDCCH - Stand-alone Dedicated Control Channel; communications channel between the MS and the BTS. Used for signalling during call set-up before a TCH is allocated



Security Code:
a numeric code (password) used to prevent unauthorized or accidental alteration of data programmed into wireless phones. The security code can be used by the owner of a phone to change the lock code.


SIM - Subscriber Identity Module
A smart card containing the telephone number of the subscriber, encoded network identification details, the PIN and other user data such as the phone book. A user’s SIM card can be moved from phone to phone as it contains all the key information required to activate the phone


Streaming:
An Internet derived expression for the one-way transmission of video and audio content


Smartphone:
a combination of mobile phone and personal digital assistant

SMS - Short Message Service
(a text message service which enables users to send short messages (160 characters) to other users. A very popular service, particularly amongst young people, with 400 billion SMS messages sent worldwide in 2002)


SP - Service Provider



SRAM - Syncronous Random Access Memory



Standby time:
The length of time a battery can power a mobile phone when it is switched on but not making or receiving calls


Symbian:
A company created by Psion, Nokia, Ericsson and Motorola in 1998 with the aim of developing and standardising an operating system which enable mobile phones from different manufacturers to exchange information
The operating system is known as EPOC. Matsua has subsequently joined Symbian



TACS - Total Access Communications System

TAP - Transferred Account Procedure
(the essential charging methodology for international GSM roaming. There have been four TAP standards, TAP1, TAP2, TAP2+ and TAP3. The latter offers variable record length and is sufficiently flexible to support all future requirements arising from the move to 3G)


TFD : Thin Film Diode
(a type of LCD (Liquid Crystal Display) flat-panel display technology. TFD technology combines the excellent image quality and fast response times of TFT, with the low power consumption and low cost of STN.)

TFT - Thin Film Transistor
(an LCD technology that uses transistors to precisely control the voltage to each liquid crystal cell. This is also referred to as an “active matrix” display. TFT screens offer the best image quality and refresh rates, but at a higher cost.)


Tri-band:
Refers to a mobile phone able to operate on the three internationally designated GSM frequencies- 900, 1800 and 1900MHz

TRX:
Transmitter/receiver (transceiver)
Total Access Communications System (an AMPS variant deployed in a number of countries principally the UK)

Talk-time:
The length of time a battery can power a mobile phone when making or receiving calls


T9 :
software built into some wireless phones and PDAs that makes typing words on a keypad easier. The competitor to T9 is iTAP


Tri-Band fone:
a phone capable of operating on three different digital frequencies (example: 900MHz, 1800MHz and 1900MHz).


U

Upp - Universal power processor

UI - User Interface



UMTS - Universal Mobile Telecommunications System
(the European entrant for 3G; now subsumed into the IMT-2000 family as the WCDMA technology.)

UPN - Universal Personal Number

URL - Uniform Resource Locator( the addressing system of the Internet)

UTRA - Universal Terrestrial Radio Access

USIM - Universal Subscriber Identity Module; the 3G equivalent of the GSM SIM

UWB - Ultra Wide Band


USB - Universal Serial Bus


VBR - Variable Bit Rate


VCO - Voltage Control Oscillator

VHE - Virtual Home Environment

VLR - Visitor Location Register

Vocoder - Voice coder

VoIP - Voice over Internet Protocol

VPN - Virtual Private Network

VSAT - Very Small Aperture Terminal

VSELP - Vector Sum Excited Linear Prediction

VSLI- Very Large Scale Integration

Voicemail:
A service offered by network operators whereby calls received when the mobile is in use, switched off or out of coverage can be diverted to an answering service which can be personalised by the user


WAP - Wireless Application Protocol
(Wireless Application Protocol; a de facto standard for enabling mobile phones to access the Internet and advanced services. Users can access websites and pages which have been converted by the use of WML into stripped-down versions of the original more suitable for the limited display capabilities of mobile phones)



WASP - Wireless Application Service Provider


Web clipping:
this is an application that allows a user to extract relevant information from a web page for display on a smart phone or a PDA.

Wi-Fi Wireless Fidelity, the popular term for the 802.11b wireless Ethernet standard.



Windows CE:
a streamlined version of Windows from Microsoft for handheld computers which has since been upgraded and renamed Pocket PC. Windows CE run Pocket versions of Microsoft office applications such as Word and Excel as well as many applications that were geared specifically for the smaller platform.

WLAN - Wireless Local Area Network
a short range radio network normally deployed in traffic hotspots such as airport lounges, hotels and restaurants. WLAN enables suitably equipped users to access the fixed network wirelessly, providing high speed access (up to 11Mbit/s download) to distant servers. The key WLAN technologies are the IEEE802.11 family and ETSI HIPERLAN/2





originally posted by: jokrads 24@sandwhich

Tips on how to Passed the CHS-NCII Tesda

---

Tips on how to Passed the CHS-NCII Tesda or Computer Hardware and Servicing National Certification Level II



I.
OHS - Occupational health and safety parang SOP - standard operating procedure din po yan amo.. kumbaga ano ba ang first move mo kapag may sira ang computer, halimbawa ganito kailangnan alamin mo muna kung ano ang history ng computer bago gawin

Quote:

common sence na po yun amo

II.
NETWORKING and CABLING
sa networking po karamihan nabagsak ang mga kasamahan ko kasi teacher sila wala silang idea about networking

Quote:

NTT-Networking Telecom Technology kasi course ko kaya yakang yaka

*kailangan sahulado mo ang color coding ng straight through cable


how to make a staright through cable google it dami procedure sa net http://www.google.com.ph/

*kailngan sahulado mo rin ang color coding ng cross over cable

how to make cross over cable? google it http://www.google.com.ph/

ang cross over cable po ay ginamit namin for PEER to PEER network para makapag file sharing and printer sharing.
pano mag peer to peer? google niyo nalang maxadong mahaba procedure ko for peer to peer



*kailangan marunong din kayong mag crimp..kasi kayo mismo gagawa ng straight through cable and cross over cable tas crimp niyo, dapat maganda pagka crimp ng cable

Quote:

with QA Quality Assurance

.
how to crimp? youtube niyo nalang dami videos diyan how to crimp

III.
INSTALLATION
kailangan marunong kayong mag install ng OS Operating System
ginawa namin 40 gb ang isang HDD Hard Disk Drive
*kailangan daw mainstall namin ang OS sa drive C: with 10Gb of size capacity tas ang drive d: is 10Gb din then yung sobra hayaan nalang daw.
kung nagloko man ang pc for installation kailang troubleshoot mo kasama sa installation yun (kung minamalas ka hehe)
kailangn marunong ka maginstall ng dalawang OS sa isang HDD
halimbawa tatanungin ka, pano iinstall ang windows 98 at windows xp sa isang HDD Hard Disk Drive?

sagot:kailangan dalawa or tatlong partion ang gagawin ko para mainstall ang dalawang os tas yung pangatlong partition ay pang buckup ko nalang
unahin mo ang win98 kasi FAT File Allocation Table file system ang format ng Windows 98
samantalang ang Winxp ay NTFS na ang format ng file system or NTFS means New Technology File System
PAGKAIBA NG FAT file system sa NTFS file system
ang FAT ay hindi kayang basahin ang NTFS samatalang ang NTFS ay kayang kayang basahin ang FAT kasi newer than FAT kumbaga Lowtech ang FAT at Hightech naman ang NTFS
kaya kailangan unahin ang win98

*kailang mo rin alamin bawat parts or component ng moderboard tulad hailmbawa ng mga

Code:

bios, buckup battery,processor, processor slot,north bridge,south bridge,agp slot,com port.parallel port,usb port,ps2 socket, pci alot,pcie slot,ddr or sdram slot, basata pag aralan niyo nalang specs ng motherboad,

IV
Assembly / OIS Assembly
kailang niyo baklasin sin ang system unit, pagkatapos mabaklas ang buong system unit ay dun kana tatanungin kung anu ba pangalan ng mga binaklas mo or sa mga specs ng mother boad
*kailangn sahulado mo rin ang bawat wattage ng power supply

ang power supply ay my tatlong clase
una ay AT- 12 pins po yan pangalawa ay ATX - 20 pins po yan at ang pangatlo naman ay BTX - 24 pins po yan google it kung hindi maintindihan

oval questioning or yan na po yung tinatawag na interview pinakahuli
karamihan tanong sa interview ay yung mga unang pingawa sayo..
sample sa interview

1.beeb codes: 1 long and 2 shorts
answer, check video card,clean the video card pins by pencil eraser or any king of eraser,clean the agp slot with WD40 or PC Vacum, swaping-> check the video card in athoer PC
unang sagot niyo ay OHS/SOP first move muna meaning niyan nasa taas ng post ko

take note:

Quote:

bago magtake ng assesment dapat kain muna kayo tas magrelax kasi ang exam namin ay umabot ng 12 hours ...buti talaga pag relax para hindi mag mental black

__________________

NTFS - allows access local to w2k w2k3 XP win NT4 with SP4
File & folder Encryption is possible only in NTFS
It also supports large volumes and powerful storage solution such as RAID.


FAT32 - Allows access to win 95 98 win millenium win2k xp on local partition
File & folder Encryption is not possible.

cmd.exe lang po ginamit ko for ms dos. how to do this? click start/run/type cmd/click ok
use this ms dos for peer to peer

mga command na nagamit ko sa assesment ito lang po amo

ipconfig/all - display full configuration information of an specified adapter

(PING) Packet Internet Groper - is a computer network tool used to test whether a particular host is reachable across an IP network
ginagamit po ang command na ito para malaman kung connected na ang ip address ng dalawang computer at pag connected na pwede ka ng mag file and printer sharing..

for configuring ip address naman ay manually po namin ginawa.for interview more on troubleshooting lang ang questions...

originally posted by: allan_canceran of gsmsandwhich.com.ph