Nokia 9000i Service Manual page 258

RAE/RAK–1N
Faultfinding/Disassembly
1.1.1.10 Reset OK?
The PWRGOOD signal should go from low to high after minimum time of
140ms when Vsys has risen to a valid level. Time between battery
connection and valid voltage at Vsys line should be in the order of 1.5ms.
If PWRGOOD signal rises too fast, or the signal levels are illegal, then go
to 1.1.1.11.
1.1.1.11 Replace D80
If this is not helping PWRGOOD line is pulled up or down somewhere or
there is a CPU fault.
1.1.1.12 LCDVEE OK?
In boot sequence LCD is on. If voltage other than 20V – 24V near room
temperature is seen at LCDVEE terminal then go to 1.1.1.13.
1.1.1.13 Is LCDVEEON enabled?
There is LCD bias voltage shutdown feature in PDA normal use after set
inactivity time period. Check that LCDVEEON line is in logic high state
(3.0V – 3.4V). If not go to 3.1.1.14. Otherwise go to 1.1.1.15.
1.1.1.14 Command LCDVEE on
Use PC Locals to command LCDVEE permanently on. Select 'I/O–Space
Functions'/'Target Signal Control' to toggle LCDVEE. This menu can also
be used to control LCDVCC, flash program voltage (VCC5) and
LCDPWM. When LCD module is not connected verify also LCDVEE off
state by toggling the control by PCLocals.
1.1.1.15 Is 0V applied to N83 pin 4?
Check that voltage between 0V and 0.3V is seen at N83 controller pin 4.
This signal enables the controller. If not go to 1.1.1.16. When LCD
module is not connected verify also LCDVEE off state by toggling the
control by PCLocals. In LCDVEE off state N83 pin 4 must see battery
voltage.
1.1.1.16 Check N82, R75, R76, R96
First check that resistors R75, R76 and R96 are OK. Check that voltage
at comparator N82 pin 3 is in the range of 1.55V – 1.75V. If not check
reference V84. In cathode of V84 voltage of 4.1V should be seen. If OK
replace N82. After that if still problems verify that comparator N82 pin 2
has higher voltage than pin 3. If yes and N82 pin 1 is not low (0V – 0.3V)
then change N83.
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After Sales
Technical Documentation
Original, 05/97