Printer and Photocopier Troubleshooting and Repair Collection : Packard Bell laser printer - strange bug
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Unresolved Problems

Packard Bell laser printer - strange bug

(From: Jordin Kare (jtk@s1.gov).)

"Just picked up a used Packard Bell laser printer with some problems and could use help...

Print engine is not one I'm familiar with. It's an 8 ppm engine that uses separate drum and developer assemblies. The drum assembly is attached to the top section, which hinges upwards. The developer assembly is attached to the bottom section, and uses a replaceable cylindrical toner cartridge similar to that used in older Canon NP-series copiers. The whole developer assembly can also be removed.

Paper tray mounts underneath unit, and paper follows an "S" shaped path through printer, stacking face-down on top. Front panel has a ~16 char. LCD display and typical button/LED set (ON LINE, Form feed, Menu, Test, Reset).

(Sorry, don't have the model # to hand. Printer was built in late 1993.)

Printer executes power on self test OK, warms up, and goes on line.

Problem 1: Take it off line and push test, and the motor whirs briefly, then stops. The LCD display then reads: 'ERROR 74-M: MOTOR'. Reset has no effect; printer must be power cycled to get it to restart.

Interesting variation: The top section is held down by two large catches at the right and left sides of the printer. The 'hooks' are released by a button on the top section. It's possible to get only the right-side hook to catch, leaving the left side 'loose' and raised by about 1/4 inch. In this condition, the printer will start up and work fine (except for problem 2 below) for many pages. Eventually, it will stop with ERROR 74-M again. Pushing down the left side will cause an immediate ERROR 74-M.

I assume there's something binding or sticking a bit in the various rollers, such that the motor draws too much current or otherwise triggers an error when the top is latched down. Releasing the top on one edge reduces the pressure on the various rollers and thus the load on the motor. But I can't find any obvious points of sticking.

Problem 2: When the printer DOES work, with the cover popped, the leading edge of the page, down to the first line of print, is dark grey. The grey is faint on the first page or after a restart or long idle, but uniformly dark on all pages thereafter. It tends to be striped along the page (varying darkness as you move left-to-right; uniform as you move top-to-bottom). The grey disappears at the first line of text. There's also a slight "ghost"; text printed near the top of a page is repeated faintly further down the page, apparently displaced by one rotation of the drum.

This seems most likely due to a bad cleaning blade or clearing corona. Anyone have any suggestions other than replacing the drum assembly? Also, anyone recognize this print engine, so I can track down parts via sources other than Packard-Bell?"

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