asked Mar 20, 2012 at 3:33pm
Hp HP LaserJet 4

HP Laserjet 4 stays in warming up mode

Hey Moe or anyone else!

Our LJ4 goes into "02 Warming Up" mode on the display when I turn it on and stays there. No gears ever turn as they do when it starts normally. I thought it might be the fuser roller lamp, but I took it out, inspected it and threw a meter on it and it seems fine. This printer's power supply crapped out a year or so ago and I bought another one from you guys. That did the trick then and I'm hoping you can help now.

Is there a way to troubleshoot and track down the problem here and order the right part? I have tools, meters, the LJ4 service manual and the desire to save money by buying your parts. I just want to buy the right one! Thanks for your help!
Most failures will result in error codes, like the fuser lamp will give you a 50 error. The formatter board is the most likely culprit. First thing I would try would be to pull it out of the printer and see if it goes past warmup. You won't see any display, but everything will run and you will be able to generate an engine test page. The formatter assy. is on the right side under the cover. Turn power off. Open the back cover and remove the left screw holding the top on. 2 screws in the back of the formatter assy., disconnect the plastic door strap. You have to open the memory access cover as well, 2 screws holding that on. 1 screw each on top, bottom and left. Then pull the assy. out a couple of inches to disconnect the power to it. Turn power on and see if it goes through its paces, then try the engine test.
by moe on Mar 20, 2012 at 4:45pm Add comment