Nokia Mobile Phones NSE-5 Series Service Manual page 230

NSE–5
Troubleshooting
1. Phone is totally dead
This means that phone doesn't take current at all when the power switch
is pressed (X400 pin 7) or when the watchdog disable pin (X201 pin 11) is
grounded. Used battery voltage must be higher than 3.1 V. Otherwise the
hardware of CCONT (N100) prevents totally to switch power on.
Phone is totally dead.
Measure voltage at
C155 (VBAT)
3.6V
No
Failure in VBAT.
Check X101, X102,
L103, L102, R102
Voltages OK?
Yes
Power doesn't stay on.
Figure 1.
Page 4
Yes
Yes
Measure voltage at V113 pin 4
(Vbb) 2.8V
C112 (end towards bottom) (VXO)
2.8V
When PWR switch is pressed or
WDOGDISABLE is grounded.
towards edge) when pwr–switch
No
WDOGDISABLE (X201 pin 11)
(Will be low only during
Yes
power–up of CCONT if
power switch is pressed.)
Check R413, V410
Faulty PCB Check LCD–module
Check WDOGDISABLE line
Technical Documentation
Measure voltage at
C153
3.6V
No
Faulty PCB
Measure voltage at R413 (end
(X400 pin 7) is pressed or
is grounded.
0V
No
Issue 1 07/99
PAMS