E8257D/67D, E8663D PSG Signal Generators Service Guide
Troubleshooting
Troubleshooting Assembly–Level Problems
1-12
The pulse state signals are control lines, clock, and data for the LCD.
Figure 1-1Pulsing Activity
5. If all the signals measured in Step 4 are good, go to Step 6.
If any of the signals measured in Step 4 are bad, check the following signals at P221 of the motherboard:
If any of these signals are bad, change the CPU board.
6. If all the signals measured in Step 4 are good, check the following signals at J9 of the power switch. To access J9
the front panel must be removed from the chassis frame and laid face down.
If these signals are good, replace the LCD.
Signal State
P221−14 VLCD approximately 21 Vdc
P221−53 LCD_ENABLE_H >3 Vdc
P221–1 to 13, 15, 41, 43, 45, 47, 49 to
52
Refer to Figure 1- 1 on page 12.
Signal State
J9−7 VLCD approximately 21 Vdc
J9−4 LCD_ENABLE_H >3 Vdc
J9−55.2 Vdc
J9−1, 2, 3, 8 to 15 Refer Figure 1- 1 on page 12.
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