Nokia 9000i Service Manual page 269

After Sales
Technical Documentation
3.1.4 Check UI Flex
In a case that the LCDVCC and the LCDVEE are within their voltage
limits, the fault is likely in the other controlling signals. But first it is good to
check the UI flex. If the UI flex is OK, proceed to 3.1.5, otherwise go to
3.1.4.1
3.1.4.1 UI Flex Fault
Change the UI Flex.
3.1.5 Check PCLK, LP, FP, DISPON
If the CPU does control the PCLK, LP, FP and the DISPON in a
reasonable manner, then proceed to 3.1.5.1 If one of the synchronizing
signals (PCLK, LP, FP) remain still all the time, or if the DISPON is inactive
(low), then go to 3.1.5.2
3.1.5.1 LCD Module Fault
If all the control signals are OK at the end of UI flex, then the possible fault
is either in the LCD module or in the UI module.
3.1.5.2 CPU Fault
If the CPU does not control all the signals as it should it is likely to be
defective.
3.2 Change LCD Contrast
To check the functionality of the contrast controlling circuitry, choose the
LCD test from the service software. Choose any test picture and then the
desired contrast value 0..255, where 0 is the darkest and the 255 the
lightest.
3.3 Contrast Change OK?
Test if the contrast changing works at least with two different contrast
values. If the contrast seems to be good in the middle, low and high of the
tunable range, then proceed to 3.4
the range bad, then proceed to 3.3.1
3.3.1 LCDPWM OK?
Test if the duty factor of the PWM output of the CPU (D130/pin134) is
changing according to the value given in the LCD test with the service
software. If the level of the LCDPWM is OK, and the duty factor is
changing from 1/255 to 254/255 then proceed to 3.3.1.2, otherwise go to
3.3.1.1
Original, 05/97
Faultfinding/Disassembly
If the contrast does not change, or if
RAE/RAK–1N
Page 8 – 27