asked Jan 7, 2002 at 6:06am
Hp HP LaserJet 4

Still getting 50 Service Error

I replaced the fusing lamp as per the instructions without a problem but I am still getting this error (HP LaserJet 4). The assembly passed the continuity test demonstrated on the video. What should I try next?

Thanks in advance.
You fall into the less than 10 percentile group with a bad power supply. The power supply is relatively easy to replace. It's under the right panel. A few screws and a couple of connectors.
by moe on Jan 7, 2002 at 8:42am Add comment
Thanks for the quick response Moe. I opened the right panel and took off the panel to the memory but I cannot see where the power supply is. Can you help. I have two of these printers to I would like to try a swap before I order again. Thanks again.
by unknown on Jan 7, 2002 at 9:07am Add comment
It's at the bottom. Follow the rod back from the power switch and it goes into it.
by moe on Jan 7, 2002 at 9:45am Add comment
Got it. Thanks a lot.

How much is a new power supply?
by unknown on Jan 7, 2002 at 2:30pm Add comment
Good morning. I took my good power supply out of my working printer at home and put it in the one with the "50 Service Error" and I am still getting the error. Note the the power supply out of my work printer worked on my home one. This leads me to believe the power supply is good. Is there any else I can try.

Thanks again for all your help.
by unknown on Jan 8, 2002 at 4:57am Add comment
I did some further resistance on the fuser assembly. Here are the results.

Dots indicate pin locations on fuser assembly.

Test 1
. . .
    | 2.6 ohms
. . .

Test 2
284.5 ohms
.-.  .

. .  .
by unknown on Jan 8, 2002 at 5:30am Add comment
The readings are correct. Only other thing that could cause it would be the DC controller board. I think I've only seen one ever do that. That's the little board next to the motor with all the connectors coming out of it. You'll have to take the formatter board off to access it.
by moe on Jan 10, 2002 at 9:15am Add comment
Thanks for the reply Moe. I was almost admitting defeat with our IT kids who have already written this printer off twice. Can you tell me what board is the formatter board?

Thanks again.
by unknown on Jan 15, 2002 at 12:32pm Add comment