Erratic Printer Operation - Tektronix PHASER 780 Service Quick Reference Manual

c.
Measure the voltage between P33-3 on the low voltage power
supply and frame ground, and between P32-11 on the low voltage
power supply and frame ground. Do you eventually measure
+5 VDC between P33-3 and frame ground, and +24 VDC between
P32-11 and frame ground? If yes, replace the component that is
loading down the power supply. If no, replace the engine control
board.
5. Image processor check
a. Turn off the printer.
b.
Remove the image processor board.
c. Turn on the printer. Does the printer go into warm-up? If yes,
replace the image processor board. If not, replace the engine
control board.

Erratic printer operation

The printer has a variety of intermittent problems, but generally does not
complete a print cycle. The problems are generally not identified by
displayed error codes.
1.
Does the printer frequently fail to enter printer warm-up or is the front
panel frequently inoperative? If yes, follow the earlier procedure
"Printer will not power up" on page 40.
2.
Run print engine test prints, which print independently of the image
processor, to determine if the image processor is the problem. Refer to
"Making a print engine only test print" on page 42.
3.
Low voltage power supply loading check
a. Run 50 test prints from the image processor's built in test prints.
b.
Measure the voltage between P33-3 on the low voltage power
supply and frame ground, and between P32-11 on the low voltage
power supply and frame ground. Is there a steady +5 VDC
between P33-3 and frame ground, and is there at steady +24V DC
between P32-11 and frame ground? If no, Replace the low voltage
power supply.
4. If test prints from the image processor print reliably, reload the host's
printer driver software or the host application software. Does the printer
still exhibit erratic operation?
5.
Try printer from another application. Ensure that the host computer
prints reliable to a different printer. Also try printing from another
computer to the Phaser 780.
6.
Replace the interface cable connecting the host to the printer.
7. Replace the engine control board.
8. Replace the image processor board.
Service Guide
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