HP 4550 Service Manual - Page 308

Engine test, Location of the engine test button

Page 308 highlights

Note Engine test The printer has one test pattern (vertical lines). When an image defect appears, a test print can be made to identify the problem. The test print can be made by pressing the test print switch located on the right side of the printer (Figure 7-21). A test pattern can be printed by pressing the test print switch once after the photosensitive drum has stopped and the printer has entered the standby mode. If the switch is held down, the test pattern is printed continuously. The switch can be used when paper is loaded in any tray other than tray 1. The engine test does the following:  Verifies that the print engine is functioning correctly (the formatter PCB is completely bypassed during an engine test).  Isolates printer problems.  Checks and adjusts registration.  Prints from tray 2 or 3 only, not from tray 1.  Can be activated with the formatter PCB removed. For the printer to perform an engine test, tray 2 must be installed and loaded with paper, and the toner cartridge must be installed in the printer. Engine test button Figure 7-21 Location of the engine test button 306 Troubleshooting C7085-90921

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306
Troubleshooting
C7085-90921
Engine test
The printer has one test pattern (vertical lines). When an image defect appears, a test print can be
made to identify the problem. The test print can be made by pressing the test print switch located
on the right side of the printer (Figure 7-21). A test pattern can be printed by pressing the test print
switch once after the photosensitive drum has stopped and the printer has entered the standby
mode. If the switch is held down, the test pattern is printed continuously. The switch can be used
when paper is loaded in any tray other than tray 1.
The engine test does the following:
Verifies that the print engine is functioning correctly (the formatter PCB is completely bypassed
during an engine test).
Isolates printer problems.
Checks and adjusts registration.
Prints from tray 2 or 3 only, not from tray 1.
Can be activated with the formatter PCB removed.
Note
For the printer to perform an engine test, tray 2 must be installed and loaded with paper, and the
toner cartridge must be installed in the printer.
Figure
7-21
Location of the engine test button
Engine test button