User Guide

TROUBLESHOOTING

9526ARo

6–2–5

NHC–4

Technical Documentation

Current consumption failures in flash station

Current consumption can fail in three ways in flash station.Typical to all these

failures is,that phone can not be programmed or tested via MBUS.The most

common failure is that phone takes almost normal current during startup and

after couple of seconds all circuits are powered down.Reason for this failure is

in power–,clock– or reset distripution of the phone.In cases where phone does

not take current at all or phone takes all available current the reason is usually

defected power ASIC PSL+ (N100) or bad soldering ( short or open ) around

PSL+ .

Phone takes all available current

If phone takes all available current,the reason for failure can be detected by:

– visual check of bad solderings in PSL+ (N100) , components around it and

bottom connector X1

– cheking ,if transistors V908,V910 and V911 in TX block are defected

Phone does not take current at all

If phone does not take current at all,check following things:

– solderingins of PSL+

– VBATT voltage should be available in pins 5 and 20 of PSL+

If connections of PSL+ are OK and VBATT in pins 5/20 is OK, change defected

power ASIC N100

Current consumption OK during power–up, then fail

The most common situation in current consomption failures is,that phone starts

almost normally,but after few seconds all circuits are powered down.The pow-

er–down is normally caused by lack of watch–dog signal from MCU to

PSL+.There are three major things to be checked in this kind of failure situa-

tion.First,check power distribution to all main components of baseband.Then

check that clock is delivered to ASIC,DSP,MCU,RFI and AUDIO CODEC.If ev-

erything is OK so far,check RESET status of circuitry mentioned above.

Cheking the power distribution of baseband

Before voltage measurements of the circuitry,power–down of PSL+ must be

prevented.This is done by shorting the watch–dog timing capacitor C106 with

wire soldered from one end of the cap to the other.

1.Check PSL+ output voltages from N100 pins 4,21,2,24 and 1.Expected value

is around 4.65V.Also,check voltage in N100 pin 12 (DETIN) to be 1.23V

2.Check supply voltage VL1 (4.65V) of MCU (D302) from pins 5 and 42.Check

VREF voltage from MCU pin 60.Check voltages of MCU related memory cir-