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

Dave Mabry dmabry at
Tue Apr 2 19:38:44 CDT 2019

Ali via cctalk wrote on 4/2/2019 3:56 PM:
> I rescued a LaserJet 4+ printer that I have been trying to restore.
> 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.
> 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.
> 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.).
> A picture of the effect can be seen on VFC at:
> Sorry for the poor quality picture.
> 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.
> 4. A visual inspection of the fuser shows it to be ok.
> 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.
> I tried posting on but for whatever reason the site
> was not accepting the question. Any other forums you guys would recommend?
> TIA!
> -Ali

Just my little bit of input on this...the high voltage power supply is 
just about the only thing that there is no error code for.  I had one 
fail and the printer didn't flag any errors.  Changing the HV supply 
fixed it.

It sounds to me like your problem is related to the high voltage supply.


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