asked Feb 12, 2001 at 11:08am
Hp HP LaserJet 4

HP LJ 4 grinding noise

I have a HP LaserJet 4 making a very loud grinding noise upon power up & initialization. I don't recall what the error message is. I usually dont let the printer run long enough to generate an error code. The noise is too intense.

I removed the printer cartridge, fuser assembly and shield plates so that I would be able to look at the main drive shaft and gear assembly. When I power the printer up, the gear assembly starts to run as the motor shaft spins (no gears are slipping). After about five seconds, the noise starts and the gear assembly stops. I noticed the main drive shaft stops spinning. With the power off, I manually rotated the motor drive shaft and it seemed to move freely. Could the main motor assembly be bad? It is strange in that the noise sounds mechanical, but the motor assembly has no mechanics. If the motor asmbly is bad, where can I obtain one ?
You can further isolate it by removing the paper feed assembly and plugging it in externally. Then defeat the door interlocks and try running it. You should be able to determine where the noise is coming from.
by moe on Feb 12, 2001 at 3:27pm Add comment
Thanks for responding moe.

I'd like to give a new definition to the noise. It's more of a groaning noise than a grinding noise. A comparable noise might be a shopVac or a leaf blower.

After doing some more isolation, the noise is definately coming from the motor and the motor shaft stops turning when the noise is present.
I removed the motor assembly. The shaft spins freely, without catch, when I spin it.
by unknown on Feb 13, 2001 at 5:54am Add comment
Try pulling the fuser and turning the gear train by hand. See if it binds. I've replaced motors that made noise in the past.
by moe on Feb 13, 2001 at 1:14pm Add comment
The motor has a tag indicating it is made by Matsushita Electric. There are two numbers on
the tag, RH7-1151 and DGQ-8C4BRA. How do I go about getting a replacement motor.

thanks !
by unknown on Feb 13, 2001 at 4:24pm Add comment
We sell it on our Repair Kits page. It's under 57 error 'cause that's what happens when it fails. Put no video in the comments field as you already know how to replace it. We'll cut the price.
by moe on Feb 13, 2001 at 5:02pm Add comment