Xerox 1235/DX Service Guide - Page 68

Missing characters or voids in print 1. Look for dirt or contamination on the LED heads. Clean them with an alcohol wipe. 2. Inspect and clean the imaging drum unit's power terminals Ensure the spring-loaded pins travel smoothly up and down. 3. Is a low-toner condition occurring? 4. Replace any imaging drum units you suspect are defective. 5. Are the LED heads' ribbon cables undamaged and properly seated? 6. Is +3.8V (red wire) supplied to Pin 3 of each LED head assembly? If yes, replace the LED head assembly. 7. Is +3.8 V supplied to the POWER connector pins 1, 2, 3, 4, 5, 6, 7 and 8 on the junction board or at the 16-pin interconnect near the top cover hinge (under the top shield plate). Inspect the junction board's wiring connectors. If the voltage is not OK, replace the low-voltage power supply. 8. If +32 volts supplied to the POWER connector pins 7, 8, 9 and 10 on the engine controller board? Inspect the wiring harnesses or replace the low-voltage power supply. 9. Is +32V supplied to the HVOLT connector Pin 5 of the engine board. If not replace the engine controller board. Transfer the old engine controller board's EEPROM (lower-right corner of board) to the new engine controller board. 10. Inspect the high-voltage wiring harnesses. 11. Replace the high voltage power supply. Service Guide 55