IBM 6643 - Manual (Page 25)

Pin Signal Function
5 COM Ground
6 5 V +5 V dc
7 COM Ground
8 POK Power Good
9 5VSB Standby Voltage
10 12 V +12 V dc
11 3.3 V +3.3 V dc
12 -12 V -12 V dc
13 COM Ground
14 PS-ON DC Remote Enable
15 COM Ground
16 COM Ground
17 COM Ground
18 -5 V -5 V dc
19 5 V +5 V dc
20 5 V +5 V dc
If the voltages are not correct, and the power cord is good, replace the power
supply.
Display
Note:
The number of defective pixels to qualify a TFT LCD panel to be replaced under warranty
is 8 or more for all types 2179 and 6643 computers.
If the screen has no display (black screen), do the following:
1. Replace power supply.
2. Replace inverter card.
3. Reseat/replace receiver board (receiver board is behind the LCD display.
If the screen comes on, then, quickly goes black, do the following:
1. Check power supply fan. If fan is running:
a. Replace inverter board.
b. Replace receiver board.
2. If Power supply fan is not running, replace the power supply.
If the screen pallet color is wrong, do the following:
1. Replace LCD signal cable.
2. Replace receiver board.
3. Replace system board.
If there are scaling problems, do the following:
1. Assure latest level video drivers are installed.
Chapter 4. FRU replacements 17