Inspecting The Low-Voltage Power Supply Fuse; Safety Interlocks - Tektronix 1235N - Phaser Color Laser Printer Service Manual

Inspecting the low-voltage power supply fuse

The 115 VAC power supply features a 20 A fuse. The 220 VAC power supply fuse
uses a 10 A fuse.
1.
Turn off the printer.
2. Disconnect the power cord from the printer.
3.
Remove the left-side cover as described in "Left-side cover" on page 88.
4. Remove the main cooling fan as described in "Main cooling fan" on
page 99. The fuse is now accessible.
If the fuse is good, but the printer's power supply does not output DC voltages,
replace the low-voltage power supply.

Safety interlocks

The printer features two safety interlock switches:
Top door-opened switch.
Front door-opened switch.
When the top cover switch is opened, the +32 VDC supply to the motors is shut
down, as well as the high-voltage power supply. When the front cover door is
opened, the +32 VDC supply to the duplex unit and high-voltage power supply is
disabled.
5. Turn off the printer.
6.
With a DMM set to measure resistance, test each switch when it is opened
and closed.
7.
Inspect each switch's wiring harness for pinches, nicks or open connections.
If you find a switch that is defective, replace it. If no motors appear to be at fault,
replace the engine controller board.
36 Phaser 1235 Network Color Printer