Verifying Power Supply Operation; Measuring Ac Power Supply Voltages - Xerox Phaser 8400 Service Manual

Verifying Power Supply Operation

Required Tools
■ TORX T-20 screwdriver
■ Digital Multi-Meter (DMM)
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 driver, which shuts down the power
supply.
(Take 20 Seconds

Measuring AC Power Supply Voltages

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.
General Troubleshooting
+50 V Supply
Active LED
to Drain Off)
+3.3 V
Supply Active
LED
+15 High Side
+12 Power
+5 Supply
Active LED
s8500-031
4-75