Nokia 5110 Service Manual

PAMS

Technical Documentation

NSE–1

Disassembly & Troubleshooting Instructions

Page 6

Original  03/98

This means that phone doesn’t take current at all when the power switch
is pressed or when the watchdog disable pin (N100 pin 29) is grounded.
Used battery voltage must be higher than 3.0 V. Otherwise the hardware
of CCONT (N100) prevents totally to switch power on.

Phone is totally dead

YES

Check R118, X300

J232

VBAT is 3.6 V

NO

Failure in VBAT line

Check X101, X102, L103

YES

Voltage at pin 29 of CCONT (N100)
is 3.6 V

NO

Faulty circuit N100

YES

N100 pin 55 (VBB) 2.8 V

N100 pin 25 (VXO) 2.8 V

when PWR switch is pressed

or watchdog disable pin is grounded

NO

CCONT (N100) pin 29 0V
when PWR switch is pressed

YES

See section: Power Doesn’t Stay On

YES

Faulty circuit N100

NO

Check UI module

In service places flash programming can be done via system connector
X100.

In flash programming error cases the flash prommer can give some in-
formation about a fault. 
The fault information messages could be:
– MCU doesn’t boot
– Serial clock line failure
– Serial data line failure
– External RAM fault
– Algorithm file or alias ID don’t find
– MCU flash Vpp error

In cases that the flash programming doesn’t succeed there is a possibility
to check short circuits between the memories and the MCU (MAD2).
This test is useful to do, when the fault information is: MCU doesn’t boot,
Serial clock line failure or Serial data line failure.