Description: UI Communication Error. The User Interface PWB detected a communication failure.
Remedy: Check each User Inferface PWB connector. Each connector is connected securely. Y↓N→Connect each connector securely. Turn the power OFF and ON. U7-1 recurs. Y↓N→Completed Replace the User Interface PWB (PL 8.4) .
Code: U8-1
Description: Billing Counter Defect. • An illegal Billing Counter value was detected. • Or, the AIOC PWB failed to read the Billing Counter.
Remedy: TBD
Code: U9-0
Description: HVPS Fail. A 500 ms cycle of HVPS#ERR=High was detected twice in a row.
Remedy: Close the Left Hand Cover and the Front Cover. Make sure that the Drum Cartridge and the Transfer Corotron are properly seated. Measure the voltages between P406-2 ( P/J406) (+)/ P406-4(+)/P406-5(+) on the AIOC PWB and ground (-). The voltages are approximately +5VDC. Y↓N→Replace the AIOC PWB (PL 8.1) and the HVPS (PL 8.2) in that order. Execute diagnostics [09-04 HVPS ON (Low Voltage)]. The voltages at P406-2 ( P/J406) (+)/P406-4 (+)/P406-5 (+) become 0. Y↓N→Replace the AIOC PWB (PL 8.1) . Replace the HVPS (PL 8.2) . The problem is solved. Y↓N→Measure the voltage between P406-1 ( P/J406) (+) on the AIOC PWB and ground (-). The voltage is approximately +5VDC. Y↓N→Check between J520-1 ( P/J520) and J406-1 ( P/J406) on the HVPS PWB for a short circuit. If there is no short, replace the HVPS (PL 8.2) . Replace the AIOC PWB (PL 8.1) . Completed