asked Sep 17, 2001 at 7:47pm
Hp HP LaserJet 4

HP Laserjet 4M Grinding Noise

Hi there,

I have a Laserjet 4M that has a VERY LOUD grinding noise during the entire print process. Once the page is finished printing, the noise stops.

However, there are no error codes. The printer prints fine, other than the noise. We have several other HP 4 series printers at work, and none makes anywhere near the amount of noise that mine does.

I have removed the Paper Tray, the Fuser, the Toner Cartridge, and I have bypassed the interlocks so I can watch the printer working with the cover open. It sounds like it is coming from the front of the printer, but I am unsure how to remove the motor to check it.

Could there be anything else possibly causing the grinding noise? Thanks in advance for your help!
Unusual that it's printing with that amount of noise. It could be the mf roller jammed and trying to turn. You can remove the PIU from the printer and plug it back in. You can then defeat the interlocks and run the printer. I've done that a few times to isolate problems. The PIU has 3 screws holding it on the left side and 4 screws in the front.
by moe on Sep 18, 2001 at 9:50am Add comment

The manual feed tray works without any paper jams.

As far as the PIU, pardon my ignorance, but what does PIU stand for?

Thanks for your help!
by unknown on Sep 18, 2001 at 10:07am Add comment
It's the whole pickup unit assy. You have to remove all the covers to get it out. If it seems too difficult, our 41.3 error kit details the whole prodedure.
by moe on Sep 18, 2001 at 5:17pm Add comment