Lexmark C920 Service Manual - Page 54

5056-XXX 925 - HVU Error Step Questions/actions Yes No 1 Has the high voltage power board (HVU) been removed/replaced? 2 Is connector CN9 on the printer controller board connected properly? 3 Did replacing the printer controller board fix the problem? Inspect the secondary card on the high voltage board (HVU) for a broken component (Q906). Replace the high voltage board (HVU) if necessary. Replace the printer controller board. Go to step 3. Problem solved. Go to step 2. Plug the connector in securely. Replace the high voltage power board (HVU). 926(K), 927(C), 928(Y), 929(M) - Toner Sensor Error 92x Service Toner Sensor Step Questions/actions Yes No 1 Is the toner cartridge the correct type for the printer? 2 Is the toner cartridge encoder wheel dirty? 3 Replace the toner cartridge for the color with the error. Did this fix the problem? 4 Test the sensors. While actuating the sensor, does the voltage fluctuate between 0 V and +5 V between pins 1 and 4 and 5, 8 and 9, 12, and 13 on CN1 on the printer controller board. Go to step 2. Clean the encoder wheel and toner sensor. Problem solved. Recommend the customer replace the cartridge with the correct type. Go to step 3. Go to step 4. Replace the printer controller board. Replace the affected toner sensor. 2-12 Service Manual