Not DEC related but still hoping for some help: Problems w/ LJ 4+ Printer

Grant Taylor cctalk at
Tue Apr 2 15:09:50 CDT 2019

On 4/2/19 1:56 PM, Ali via cctalk wrote:
> I rescued a LaserJet 4+ printer that I have been trying to restore.

I miss my 4M+ with duplexer and extra paper tray.  :-(

> Initially everything seemed ok and it seemed as if there may be just a bit 
> of an issue with paper pickup which I attributed to old paper in the tray.

I've found that the age of the paper isn't as important as any dust 
accumulated on the top sheet.

> However, soon I started getting the accordion paper jam which led me to 
> replacing all the rollers including the transfer roller. Now the paper 
> flows freely!


> However, I am having a new problem with printing. When I print, the 
> first 5-10 pages initially come out blank. The printer does not produce 
> any errors or error codes. The blank pages are warm (not hot though) 
> as expected out of a LJ.

I thought that there was a temperature sensor to detect how hot the 
fuser is and error if it's not warm enough.

> After closer inspection it seems that the pages are printed 
> SUPER light and gradually get darker the more I use the printer 
> continuously. Eventually the printer starts printing continuous crisp 
> black pages like new. This is a whole page phenomenon (i.e. not gaps, 
> missing areas, etc.).


I would question if there is an issue with the High Voltage and 
transferring from the transfer roller to the paper.  But you said you 
checked the High Voltage.  I thought the printer would detect this error 
condition too.

> A picture of the effect can be seen on VFC at: 
> Sorry for the poor quality picture.

I can't sign in to look at the picture.  If I can, I'll look at it later.

> Things I have checked/tried:
> 1. Using a brand new NOS toner (according to HP toner does not go bad 
> as long as it was sealed - which this was)
> 2. Swapping the new transfer roller for the old one - same problem, I have 
> to print out a bunch of pages until the printer starts acting normally.
> 3. I have checked the HV and an image is being transferred to the drum 
> on the toner cartridge.

How dark is the image that's being transferred to the drum?

If the normal image is being transferred and toner is being consumed, I 
would wonder where the toner is going.

How clean / dirty is the fuser cleaning pad?

> 4. A visual inspection of the fuser shows it to be ok.

This doesn't sound like a fuser issue that I recall.  Unless it's not 
warm enough.  (Again, the printer should detect this.)

> Obviously this is happening printing demo pages so it has nothing to do 
> with computer, OS, SW, drivers, etc.

> Anybody run into this before? Any ideas/suggestions. My Google fu turned 
> up a bunch of discussions on the laser door not being aligned correctly 
> but that would seem to be a more permanent issue i.e. unless you fixed 
> the door no pages should print ever.


> Mine gets better on its own after a number of pages are printed. Plus 
> the door and spring are fine - I checked them just in case.

So, it needs to be something that can change while the printer is operating.

The things that come to mind are shifting High Voltage (…) and temperature.

The other thing that comes to mind is possibly toner caked up in the 
toner cartridge.

How long can you wait after getting a good printout before they start to 
fade again?  (Assuming the printer stays on.)

> I tried posting on but for whatever reason the 
> site was not accepting the question. Any other forums you guys would 
> recommend?  TIA!

I'll share your email with a friend who was a certified HP LaserJet 
repairman.  (I just pretended to be one a couple of jobs ago).

Grant. . . .
unix || die

More information about the cctech mailing list