HP Laserjet 4: Paper Jam

[oliaros]

Hello out there,
my LJ4 refuses to take paper from the (manual) tray 1 as well as from tray 2 (cassette). Error code is "13 Paper Jam". Error is cleared by opening the top cover. No paper is left in the paper way. It seems, that during start of printing the sheet feeder does not move. I removed the sheet feeder, checked the cables, but no result. Is there a test procedure for the sheet feeder esp. the motor? Do you have any other hints?
Regards, oliaros

[Big Al]

Hi:
Could you help us with a little more information? When you turn the printer on part of the Power On Self Test is to run the motors to clear out any left over paper in the paper path. Do you hear this operation? Can you help us with a sheet feeder description? I am not familiar with that term. The 13 error code means the printer thinks there is paper somewhere or you have a defective sensor. Cut a two inch wide strip off a manila folder and use it to probe the paper path for a fragment left over from a jam. Any idea what may have started this? There is a paper present sensor on the fuser that can do this.

What are your options? Can you find another LJ 4 to swap parts with? There is not much wisdom in spending much money on a LJ 4 when a replacement is so inexpensive. The LJ 4+ and LJ 5n use the same toner cartridge and NIC.

[oliaros]

Hi,
as far as I see we have two motors inside the LJ4. If you face the printer on the left side ist the sheet feeder mechanism, on the left side the fuser and paper output mechanism. On POST I can hear a motor running an the rollers on top of the printer turn. But I have no hint that the paper feed motor turns. I removed the paper feeder unit as well as the fuser unit but I could not see paper on one of the 3 sensors. But it is strange anyway: The printer just stopped to work. I switched it off, and next day I had this paper jam error. That's why I try to find the reason, I just think it's unlikely that overnight a severe fault can happen. Unfortunately I can not just change parts, but clearly it is not worth to spend any money in that printer... I just would like to know what's wrong.
Regards & thanx for the respond,
oliaros