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.



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.

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



Shorted Phones (No Power) Part i

Hello mates.
Today I will bring you Tips how to Repair Shorted phones with 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 heating. if some one heats, remove it and apply 3R to it. (Re solder, Re ball, Replace)