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Service Guide
41
Testing for shorted drivers
1.
Turn off the printer.
2.
Disconnect the +40 DC loopback connector (the 4-pin connector with
the two loopback wires) from J250 at the top of the power control
board. (This isolates the Y-axis motor, process motor, X-axis motor,
paper feed motor, vacuum pump, solenoids and clutches).
3.
Attach the service load connector to J250 on the top of the power
control board (behind the printhead) to simulate a load on the power
supply. Attach the service load connector’s ground clip to the printer
frame. Do not leave the service load connector in place and powered-
up for longer than 5 minutes; it gets hot from the current load.
4.
Turn on the printer. If the rear panel LEDs illuminate (indicating
power), the power control board or its loads are current-limiting the
power supply. Go to Step 5. If no power is evident (no lit LEDs),
replace the power supply.
5.
Turn off the printer. Reconnect the +40 volt service connector to the
power control board; then disconnect all load connectors from the
power control board. Turn the printer on. If the rear panel LEDs still
do not illuminate, the power control board has a shorted driver and
must be replaced. If the LEDs do illuminate, isolate which motor or fan
is overloading the power control board and power supply by turning
off the printer and sequentially plugging each cable in one at a time
and turning on the printer until the power supply is disabled. Replace
the defective component. Also refer to the next topic “Testing for a
shorted motor” on page 42.
6.
Turn off the printer. Disconnect the two I
2
C bus cables from the power
control board. (This isolates the I/O boards and their solenoid drivers.)
If the rear panel LEDs illuminate, isolate which I/O board is shorting
or which I
2
C cable is defective.
7.
If the power supply still does not work, replace the power supply.
Attaching the service load connector to J250
0388-66
Service load
connector
J 250
Warning: AC voltage
hazard. Never attempt
to plug service load
connector here.
Summary of Contents for Phaser 840
Page 46: ...36 Phaser 840 Color Printer ...
Page 95: ...Service Guide 85 Clearing PostScript NVRAM menu item ...
Page 96: ...86 Phaser 840 Color Printer ...
Page 121: ...Service Guide 111 Figure 1 Cabinet FRUs 7 5 6 8 1 2 4 0388 21 3 ...
Page 125: ...Service Guide 115 Figure 3 Paper path FRUs 0388 16 2 1 5 11 10 9 12 6 4 3 7 13 8 ...
Page 127: ...Service Guide 117 Figure 4 Motors and fans FRUs 0388 14 7 4 3 5 6 2 1 ...
Page 129: ...Service Guide 119 Figure 5 Circuit boards FRUs 4 3 5 2 1 9 7 6 8 10 11 13 0388 13 12 ...
Page 131: ...Service Guide 121 Figure 6 Solenoids and clutches FRUs 4 5 3 2 1 0388 23 ...
Page 137: ...Service Guide 127 Figure 9 High capacity PaperTray 0388 65a 1 2 ...
Page 142: ...132 Phaser 840 Color Printer ...
Page 154: ...144 Phaser 840 Color Printer ...