Xerox Phaser 7760 Service Manual page 87

004-376 Zero Crossing Signal Not Detected
The zero crossing signal is not detected.
Procedure
Check that J590 on the AC Drive PWB (PL
Check that J412 on the Engine Control Board (MCU PWB)
Check the condition of the wires between J590 and J412
wires are good.
Y N
Repair as required.
Measure the voltage at 590-1 on the AC Drive PWB (pin 1 is toward inside of machine). Check
for both DC and AC voltages of 0.44 VDC and 0.92 VAC
approximately 0.5 VDC and 1 VAC.
Y N
Measure the voltage at J590-7 (pin 1 is toward inside of machine) for +5 VDC. The volt-
age measures +5 VDC.
Y N
The wires were previously checked. Replace the Engine Control Board) (MCU PWB
(PL 13.1).
Measure the voltage at J590-5 (pin 1 is toward inside of machine) for less than +1 VDC.
The voltage measures less than 1 VDC.
Y N
The wires were previously checked. Replace the Engine Control Board (MCU PWB)
(PL 13.1).
Replace the AC Drive PWB (PL 9.2).
Measure the voltage at J412-19 on the Engine Control Board (MCU PWB). The voltage mea-
sures less than 1 VDC.
Y N
Repair the open circuit between J590-1 on the AC Drive PWB and J412-19 on the Control
Board (MCU PWB).
Replace the Engine Control Board (MCU PWB)
Revised
Phaser 7760 Color Laser Printer
9.2) is securely connected.
(PL 13.1) is securely connected.
(Figure 1). The connections and
(Figure 1). The voltage measures
(PL 13.1).
Figure 1 004-376 Zero Cross Signal and Fuser Relay
January 2010
2-51
Status Indicator RAP's
004-376