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3-40 Phaser 8400/8500/8550/8560 Color Printer Service Manual
Error Messages and Codes
50V Power Supply Fault Troubleshooting Procedure
Step Questions and Actions
Yes No
1 Check for a short in the Electronics Module.
NOTE Damage to circuits within the Electronics
Module may occur if the power supply
capacitors are not allowed to fully
discharge.
NOTE It is possible that the power supply is not
shorted, but instead is out of spec and
can lead to an error condition.
1. Measure the 50 V power supply output.
The test point is located on the power
control board below the main board RAM
DIMMs.
2. Is the power supply within specification?
3. Turn Off the printer and wait 30 seconds
for the capacitors to discharge.
Go to Step 2. Go to Step 2.
2 1. Unplug the following Electronics Module
connectors. This step disconnects all
other external circuits so the Electronics
Module can be tested alone:
■ Power Control to I/O board (J800 - gray
ribbon cable on right side)
■ Power Control right (J400 – 16 wire,
multi-color)
■ Printhead data interface (J130 – gray
ribbon cable on top side)
■ Wave amp signal (J790) short gray
ribbon cable located on left side)
■ Printhead power connector
■ Power Control left (J390 – 34 wire, multi-
color)
■ Y-Axis motor (J280)
2. Turn on power to the printer.
Do the PE and PS indicators (near the power
switch) flash momentarily?
Go to Step 3. Replace the
Electronics
Module.
3 1. Turn off the printer and wait 30 seconds
for power supply capacitors to discharge.
2. Plug in the power control to I/O board
connector (J800).
3. Turn on power to the printer.
Do the PE and PS indicators flash
momentarily?
Go to Step 4. Go to Step 5
4 If the 50V Power Supply LED (viewed thru the cooling grill below the power
cord receptacle) illuminates, the short is on one of the external devices you
unplugged earlier. In this case, systematically turn off the printer, plug a
wiring harness back in, and turn the printer on until the 50V supply fails (see
“Measuring DC Power Supply Voltages” on page 65).
Replace the defective part. Retest the printer.