renegade99

asked May 9, 2015 at 12:06pm
Hp HP LaserJet 4L

HL 4L with paper jam flashing all the time

Hello,
My old HP 4L shows a paper jam flashing light that will not go off. When I unplug the printer and try to reset it by connecting it while holding the top power lever, this is what happens:

- it stays silent
- there is one click sound (like a relay)
- the left top panel lights come up one time
- then paper keeps blinking

I took the printer apart looking for any paper jam but there is not any. Checked both relays and they are clean. I even saw another post that starts with the same behavior I described but I am not getting any luck with my troubleshooting. I even looked at the manuals but nothing jumps at me.

I have run out of options as to what to check and I am thinking that maybe my printer reached the end of its life: I got it in 1995! I really don't want to throw away but if the issue is with the main board, then I am out of luck.

The other issue is that when I took it apart, there was a small part that came lose and I cannot figure out where is goes. It is part no. RB1-2970 with N2-5 right below the numbers. I think the part is called a paper rocker and it does not look broken.

I am troubled that when I plug in the printer, no fan comes up and just the paper jam light blinks rapidly. I apologize for this long post but wanted to give as much info as possible. Thank you for any feedback.

renegade99
Ok, I looked at #9 at this site, http://tubesound.com/2010/04/29/hp-laserjet-4l-4p-refurb-and-repair/ but still not sure where the parper rocker goes in. I suspect that my issue is related to this part not being installed in the printer.

Anybody has any pointers on how to fix this problem?
by renegade99 on May 16, 2015 at 7:26am Add comment
It goes in that black plastic area just to the right and below where it is shown in the picture. When the paper comes out of the tray, it will push that arm and it actuates a photosensor on the board that would sit above it. No arm and it will give you a paper jam indication.
by moe on May 18, 2015 at 3:08pm Add comment
Hi moe,
Thanks for your timely response. I managed to get the printer together and when I plug it in, I can print a test page by pressing the blue bar on the front, left side, but right after the page is out, I get the paper jam light even though there is no paper on the path. I am troubleshooting to find the reason for this behavior. If I unplug it and plug it back on, it comes up fine without any error but it lets me print just one page and then issues the paper jam error. - renegade99
Problem resolved: I had the wrong paper source in the printer properties in Windows. Instead of "paper casssette", the paper source was automatic. Once I made the change, I was able to print many pages without any paper jam errors. I am happy as a clam because now my work horse printer is back for good! The giveaway here was that I was able to print a test page from the printer itself but it gave me an error at the end of the printing cycle and nothing but a thump would be heard when I tried to print from my PC. I hope that this long post can help anybody that may face a similar problem with their HP laserjet 4L. Cheers!!
by renegade99 on May 20, 2015 at 12:44pm Add comment