How To Check Short In All Nokia And China Mobiles

[gsm logic]

most importantly these works great for all china phones, since some ics in nokia pcb will obstruct ur reading, its is advisable to first remove ics so as to enable check components like resistors, capacitors, diode, transistor etc. here are my findings and dont forget to press thanks.

How to Check Parts of a Mobile Phone for Fault


When doing mobile phone repairing, you will often need to check parts such as speaker, ringer, vibrator, coil, boost coin, On / Off Switch, Antenna Switch, RX Filter, PFO, BSI, Network IC, VCO, Audio IC, Power IC, RTC, Charging IC, CPU, R22, Microphone Interface, Bluetooth IC, Flash IC, RAM, Logic IC, UEM etc.
In most cases, only card level parts of a mobile cell phone are checked for fault and then repaired or replaced with a new one. Card level parts of a mobile cell phone include ringer, speaker, microphone, vibrator, LED, charging connector, headphone connector, data cable connector, battery, battery connector, SIM card, SIM card connector, memory card, memory card connector, camera, camera connector, keypad button, keypad connector, ON / OFF Switch, Display, Display connector, Internal antenna and PDA.
Chip level small parts of a mobile phone that include small electronics components like capacitors, resistor, diode, coil, boost coil, coupler, regulator, transistors, are rarely or not tested for fault. In case there is any fault in the track of the Mobile Phone PCB then it is solved or fixed by jumper.
Mobile Phone Tools and Equipment Needed to Check Parts of a Mobile Phone for Fault are:

• Multimeter
• DC power supply

How to Check Parts of a Mobile Phone for Fault

• Ringer: To check if the ringer of a mobile phone is faulty or damaged, Multimeter for Mobile Phone Repairing
  
  keep the multimeter in buzzer mode and check the ringer. Value must be between 8 to 10 Ohms. If the value is between this range then the ringer is good and does not need replacement. If the value on multimeter is 4-5 or 12-14 then change the ringer.
• Vibrator or Motor: Keep the multimeter in Buzzer Mode and check the vibrator, Value must be 8 to 16 Ohms. If the value is between 8-16 Ohms then the vibrator is good. Otherwise change it.
• Speaker or Earpiece: Check the speaker / earpiece with a multimeter on Buzzer mode. Value must be in the range of 25 to 35 Ohms. If the value is in this range then the speaker / earpiece is OK and need not be changed. Otherwise, change the speaker / earpiece.
• Microphone or Mic: Keep the multimeter in buzzer mode and check the microphone. Value reading on the multimeter must be in the range of 600 to 1800 Ohms. There will also be a Beep or Buzz sound from the multimeter. NOTE: Please note that only one side of the microphone will show value. If we check by reversing the Red and Black Probes / Test Leads of the multimeter and check the microphone then there will be no value.
• Coil: Check it with a multimeter on Buzzer Mode. If it is good then it the multimeter will give a Beep or Buzz sound. If there is no sound then the coil is faulty. Replace it with a new one.
• Resistor or Resistance: Check it with a multimeter on Buzzer Mode. If it is good then the multimeter will give a Beep or Buzz sound. If there is no sound then the resistor is faulty. Replace it with a new one.
• Capacitor: Check it with a multimeter on Buzzer Mode. If it is good then the multimeter will NOT give any Beep or Buzz sound. If there is sound then the capacitor is faulty. Replace it with a new one.
• Diode: Check it with a multimeter on Buzzer Mode. If it is good then the multimeter will NOT give any Beep or Buzz sound. If there is sound then the diode is faulty. Replace it with a new one.
• LED: Keep the multimeter in Buzzer mode and check the LED. If the LED is good then they will glow otherwise not.
• Coil and Boosting Coil: Check for continuity. If there is continuity then the coil or the Boost Coil is good otherwise it is faulty.
• Keypad: Keep the multimeter on Buzzer mode and check Rows and Columns or the Key Pad. If there is Beep or Buzz sound from the multimeter then Keypad is ok, otherwise it is faulty.
• Battery Connector: Keep multimeter on 20V DC and check. Value must be 1.5 to 3.5 V DC.
• Battery: Check voltage with a multimeter. Keep multimeter on 20V DC and check. Value must be 3.7 V DC or above.
• ON / OFF Switch: Check voltage with a multimeter. Keep multimeter on 20V DC and check. Value must be between 2.5 to 3.7 V DC.
• Network IC: Use a Analog DC Power Supply to check Network IC. Switch ON DC Power Supply and call any number from your mobile phone. The Needle of the DC Ampere will start moving. This shows that the Network IC is OK and not fault.
• Power IC and CPU: Adjust voltage of the DC Power Supply to 4.2. Place the Red Probe / Test Lead of the DC Power Power Supply to the “+” of the Battery Connector of the mobile phone and the Black Probe / Test Lead to “-”. If DC Ampere is over 6 then Power IC or CPU is damaged. Check by replacing Power IC and the CPU one by one.
• If there is no movement of the Ampere Needle of the Power Supply then the Battery connector, On / OFF Switch Track, RTC or Network Crystal is damaged. Give heat to these components using hot air ****er. If the problem is not solved then check by replacing them one by one.
• If the Ampere Needle fluctuates below 2 ten there could be problem with software or RTC (Real Time Clock).
• If the Ampere needle stands at some fixed point then there is problem with the Flash IC.
• If there is beep sound from the DC Power Supply then there is problem with “+” and “-” or the mobile handset is short.

PS: When checking a faulty mobile phone with DC Power supply, connect the Red Probe to “+” and Black Probe to “-” of the Battery Connector of the Mobile Phone.
DC Power Supply


Notes:

• Most mobile phone repair people and technician check only above parts of any mobile phone to solve hardware problems.
• All other parts including electronic components and ICs are generally not checked for fault. There is no good sure test for these parts. The problem is either solved by jumper or by trial and error (check by replacement).

[gsm logic]

dont forget a good visual inspection is key to finding short components

[gsm logic]

this might also help,.
When I read some threads on GSM Forum its Funny to see some people's way of finding shorts on mobile phones. I am not going to talk about their methods. There are no different methods to find out that on Chinese Mobiles and others like Nokia,Samsung etc..

All mobile Short finding method is same.

The Very basic method to find if there any short on a mobile is using Analog Multimeter.

Put multimeter to x10
Check Battery Connector pins

simply put (+) test probe on GND pin and (-) test probe on Vbat Pin

if the multimeter pointer moves even a little there is a short.

You also can use a DC power supply for testing Short but this is better to find where or which part is really short. This way is not a good way to identify a short, because Power supply can't detect very small shorts which cause some faults on mobile. So remember the best method is using a multimeter.

Ok. How to find if a phone shot or not using DC power supply

Put power to your mobile using Power supply(As your mobile's power needs) Normally 3.8V is enough
some Chinese phones needs 4.2v

Connect Red clip to V bat pin
And connect Black clip to both BSI and GND
Do not touch any key or button


If you’re Power supply's Current panel shows any of current amount that’s mean there is a short in it.
If your Power supply Shows “0.00” on current panel it means there is No No No..any short
Don't Forget to Adjust "0" ohm before the operation.
Using Analog Multimeter
..None Faulty Mobile..



..Faulty Mobile..



Using DC Power Supply

..None Faulty Mobile..




..Faulty Mobile..



Remember in mind

When you check some mobiles specially chines mobiles with Spreadtrum Chip inside, They shows some current consume when you connect is to Power supply. after a while it will count down to "0" don't treat this as a short.
Short is Fault's Friend

Why

There are two types of Short circuit mobiles.

i. Mobile which are does not Powering on
ii.Mobiles which are Powering on.

Powering on Shorted Mobiles.
This type of short does not effect to power on a mobile. The phone is normally powering on. But there is a short and a fault.

HOW Short is Friend of Fault?

ex: There is a mobile with No Network on it.

when you check it,multimeter shows some short on it. Fault is No Network so it is the most hint to us find out where is really shorted.

this time its Network Part of mobile.

there for this short 99% should come from Network side components of mobile.

HOW To Find out


i. Clean the PCB using ISO Propyl Alcohol.
ii.Check Antenna for bad contacts.
iii.Put power to mobile using DC power supply, Check if there any IC(This time FEM & RF IC) or component heating.
iv. If any IC or part heating remove it. and you will see the sort has disappear.

How to Repair


Add 3R

what is dame 3R?

Re Solder
Re Ball
Replace

add 3R one by one. Your fault should be solved...

All shorts with powering on are same method to repair. You know the fault so you know where is shorted

ex 2 :
if Not charge Betty IC or UEM, charging port etc.
if No Display Display IC, Display connecter, etc
like that. For identification about which parts are effected with fault,best way is studying Schematic Diagrams. For Chinese mobiles you need some Experience to do it.

Glossary

UEM= Universal Energy management ( Power IC)

FEM= Frequency Energy management (Power Amp)

RF IC = Network IC
IC= Integrated Cercuits
How to Repair Shorted Mobiles Which "No Powering ON"
First of all you must follow the basic.

i. Full clean PCB carefully using ISO propyl Alcohol.

ii.Check Battery pin & On Off switch ways.

Why?

Imaging that you made the repair successfully. But your battery pin is loose. will your mobile power on? NO

If your on off way or key damaged? will your mobile power on after you repair the fault? NO

so everything must be clear before the repairing progress.

Ok . now you have cleaned PCB, confirmed Bat pins & good on off way.

everything clear and now we can repair the Short.

How To

Put power to your mobile using DC power Supply if your phone full shorted give 0-1.5v to phone. if normal short, 3.8v to 4.2v is ok. Carefully find out if any part or IC heaNext Lesson: How to repair Non Heating Shorted phones which are no ting. if some one heats, remove it and apply 3R to it. (Re solder, Re ball, Replace)
Other steps include-
-Change charging jack
-remove charging ic
-remove very capacitor one at a time and power on the phone inbetween every removal.
-check on/off switch.
-if phone shows charging sign but wont power when plugged to the wall socket, then check short in on/off button and apply jumper.

[gsm logic]

Most times, when a shorting phone is brought to your shop, you will observes it gets hotter in the whole pcb, when a battery is connected and phone power on- 1-check short in the lcd legs.2-check usb charging jack legs.3-remove and replace either of these two culprits, CPU Or Power ic.

[gsm logic]

NEXT TUTORIAL WOULD BE, HOW TO REMOVE AND REBALL MOBILE CPUs-

[N.C.Erepola]

Originally Posted by gsm logic

this might also help,.
When I read some threads on GSM Forum its Funny to see some people's way of finding shorts on mobile phones. I am not going to talk about their methods. There are no different methods to find out that on Chinese Mobiles and others like Nokia,Samsung etc..

All mobile Short finding method is same.

The Very basic method to find if there any short on a mobile is using Analog Multimeter.

Put multimeter to x10
Check Battery Connector pins

simply put (+) test probe on GND pin and (-) test probe on Vbat Pin

if the multimeter pointer moves even a little there is a short.

You also can use a DC power supply for testing Short but this is better to find where or which part is really short. This way is not a good way to identify a short, because Power supply can't detect very small shorts which cause some faults on mobile. So remember the best method is using a multimeter.

Ok. How to find if a phone shot or not using DC power supply

Put power to your mobile using Power supply(As your mobile's power needs) Normally 3.8V is enough
some Chinese phones needs 4.2v

Connect Red clip to V bat pin
And connect Black clip to both BSI and GND
Do not touch any key or button


If you’re Power supply's Current panel shows any of current amount that’s mean there is a short in it.
If your Power supply Shows “0.00” on current panel it means there is No No No..any short
Don't Forget to Adjust "0" ohm before the operation.
Using Analog Multimeter
..None Faulty Mobile..



..Faulty Mobile..



Using DC Power Supply

..None Faulty Mobile..




..Faulty Mobile..



Remember in mind

When you check some mobiles specially chines mobiles with Spreadtrum Chip inside, They shows some current consume when you connect is to Power supply. after a while it will count down to "0" don't treat this as a short.
Short is Fault's Friend

Why

There are two types of Short circuit mobiles.

i. Mobile which are does not Powering on
ii.Mobiles which are Powering on.

Powering on Shorted Mobiles.
This type of short does not effect to power on a mobile. The phone is normally powering on. But there is a short and a fault.

HOW Short is Friend of Fault?

ex: There is a mobile with No Network on it.

when you check it,multimeter shows some short on it. Fault is No Network so it is the most hint to us find out where is really shorted.

this time its Network Part of mobile.

there for this short 99% should come from Network side components of mobile.

HOW To Find out


i. Clean the PCB using ISO Propyl Alcohol.
ii.Check Antenna for bad contacts.
iii.Put power to mobile using DC power supply, Check if there any IC(This time FEM & RF IC) or component heating.
iv. If any IC or part heating remove it. and you will see the sort has disappear.

How to Repair


Add 3R

what is dame 3R?

Re Solder
Re Ball
Replace

add 3R one by one. Your fault should be solved...

All shorts with powering on are same method to repair. You know the fault so you know where is shorted

ex 2 :
if Not charge Betty IC or UEM, charging port etc.
if No Display Display IC, Display connecter, etc
like that. For identification about which parts are effected with fault,best way is studying Schematic Diagrams. For Chinese mobiles you need some Experience to do it.

Glossary

UEM= Universal Energy management ( Power IC)

FEM= Frequency Energy management (Power Amp)

RF IC = Network IC
IC= Integrated Cercuits
How to Repair Shorted Mobiles Which "No Powering ON"
First of all you must follow the basic.

i. Full clean PCB carefully using ISO propyl Alcohol.

ii.Check Battery pin & On Off switch ways.

Why?

Imaging that you made the repair successfully. But your battery pin is loose. will your mobile power on? NO

If your on off way or key damaged? will your mobile power on after you repair the fault? NO

so everything must be clear before the repairing progress.

Ok . now you have cleaned PCB, confirmed Bat pins & good on off way.

everything clear and now we can repair the Short.

How To

Put power to your mobile using DC power Supply if your phone full shorted give 0-1.5v to phone. if normal short, 3.8v to 4.2v is ok. Carefully find out if any part or IC heaNext Lesson: How to repair Non Heating Shorted phones which are no ting. if some one heats, remove it and apply 3R to it. (Re solder, Re ball, Replace)
Other steps include-
-Change charging jack
-remove charging ic
-remove very capacitor one at a time and power on the phone inbetween every removal.
-check on/off switch.
-if phone shows charging sign but wont power when plugged to the wall socket, then check short in on/off button and apply jumper.

Please brother next time when you copy paste others post please add Original posters name to give a credit to him. This is the link to above thread.
http://forum.gsmhosting.com/vbb/f782...hones-1716880/

[gsm logic]

Originally Posted by N.C.Erepola

Please brother next time when you copy paste others post please add Original posters name to give a credit to him. This is the link to above thread.
http://forum.gsmhosting.com/vbb/f782...hones-1716880/

yeah it true i copy and paste w/o giving credits to d original poster. BUT OF WAT USE IS THEIR WORK IF THEY DONT IMPROVE OR EXPANSIATE ON IT, OF WAT DAMN USE IS POSTING HALF RESEARCH ONLY FOR ANODA PERSON LIKE ME TO STRONGLY IMPROVING ON IT AND TOUCHING OTHER AREAS HE NEVER CARE TO TOUCH. CUZ WHEN IT COMES TO CELLPHONE HARDWARE REPAIRS A WHOLE LOT OF THINGS ARE INVOLVE. TANX

[gsm logic]

Originally Posted by gsm logic

NEXT TUTORIAL WOULD BE, HOW TO REMOVE AND REBALL MOBILE CPUs-

special tanx to Saqib Islam for the wonderful cpu reballing tutorial pix, here is the linkhttp://repair-mobiles.com/how-to-reball-ic-full-guide-with-images/ my goal is to make dz thread a no.1 repository for all mobile hardware repairs cuz me alone cant do dz. dont forget to press thanks.

[gsm logic]

Next tutorial would be how to run 'all china mobiles no display light on lcd- tanx pls stay with us

[gsm logic]

How To Reball IC full Guide With Diagrams - Others Diagrams

[gsm logic]

Originally Posted by gsm logic

How To Reball IC full Guide With Diagrams - Others Diagrams

special tanx once to saqib islam for these useful reballing ic tutorial pix

[newjazzy]

pls can i use my digital meter to solve usb not charging fault on china phone

[jacobkhan]

Hi, brother the way you clarified in detail about checkin shorting and removing it is tremendous. Hats off.
But you didnt tell us why put 1.5v to a full short phone.
Please throw light upon this question of mine. And the way you are educating and rendering great cause and contributing a positive role in the society by sharing knowledge. *** bless you!

[kommurik99]

need continuity value for all sections
like battery connector value one side 350ohms and second side(1100) not standing values
most help full for all technician

[Rkumar08031974]

hi

friends

i have mobile model karbonn a29. when i insert bettary it start powering on and than on/off switch stop working


please help