Verifying Power Supply Operation; Measuring Ac Power Supply Voltages - Xerox PHASER 8500 Service Manual

General Troubleshooting

Verifying Power Supply Operation

Measuring AC Power Supply Voltages

4-64
The power supply is divided into two sections: the AC section used for heaters
and the DC section for control logic, Printhead drivers, and motors. Verifying
the power supply involves three steps:
1. Checking for proper AC voltage.
2. Inspecting the power supply fuses.
3. Testing for a shorted motor or solenoid, which shuts down the power
supply.
+50 V Supply
Active LED
Supply Active
(Take 20 Seconds
to Drain Off)
1. AC line voltages are present on the power supply and possibly in the
printer, via the heaters, while the printer is plugged into an AC outlet. The
power switch is detected by software; a proper shut down follows a power
off signal to the power supply. The printer may operate for a considerable
time after this procedure.
2. Turn off the printer, wait for shutdown, and unplug it from the power outlet.
3. AC Input: With a DMM set to measure AC voltages, measure the power
being supplied to the printer; it should measure between 90 to 140 VAC
(115 VAC nominal) or 180 to 264 VAC (220 VAC nominal).
4. Proceed to the step, "Testing Motor and Solenoid Resistances" below.
5. If a heater shorts, F2 or F3 opens. The power supply does NOT shut
down; however, a Service Required error code is displayed on the
Control Panel.
+15 High Side
+3.3 V
+12 Power
+5 Supply
LED
Active LED
s8500-031
Phaser 8400/8500/8550/8560 Color Printer Service Manual