HP Laserjet 4100 stopped working

[oldprinter19]

Printer HP Laserjet 4100.
No network card, no internal harddrive.
Printer was working well, problem came
up on sending a print job to the printer.

Problem: on startup, after switching
on, fan starts, engine starts, display
counts memory up to 32 MB. (installed quantity)
After reaching that value, engine stops,
fan seems to stay running (outlet on the
left side of the machine still sucking).
Display shows 32 MB on the first line,
added with asterisks and the second
line are asterisks too.
The 'ready' text does not come up.
None of the buttons on the panel gives
any reaction.
Trying a cold reset ('go' and switch 'on')
gives no reaction on display.
The engine test (pin in small hole on
the left side, kept there) produces a
sheet with lines.
Took out the ram-module and switched the
printer on: the display shows
53.10.03, which looks okay for the situation.
Reseated the ram in the same slot again.
Took out the rom-module (which looked okay
too) and reseated it.

As the printer is in good condition, and i
love to use it again, my questions:
-does this all point to a bad formatter?
-would a new/other formatter cure the problem?
-can i switch the rom and ram module to an
other formatter?
-is the c4169-67901 the correct replacement?

Thank you for your input/help.

[Repairatrooper]

Remove the formatter and try to print an engine test. If that works then you can be reasonably certain that it is the formatter and not the DC controller or power supply. I have to check on the part number bit will and post back. Meanwhile you can do the engine test.

[east2100]

If it is the formatter's issue after your doing as @Repairatrooper  saying you may like to try to save the formatter back by baking it in the oven.

https://www.youtube.com/results?search_query=HP+laserjet+P2015+bake

https://www.youtube.com/watch?v=ErGK9VU2ivM&t=19s

https://www.youtube.com/watch?v=kPDSNqFGGmI&t=421s

Not the same model as 4100 but you can try it anyway.

[Repairatrooper]

The part number you posted is correct part for the 4100.

[oldprinter19]

Thank you both for the friendly and helping answers.

Can I switch my printer on -without any danger for problems- with the formatter board removed (to do the engine test)?

And: on one of the youtube movies I did see a HP laserprinter formatter board, with a battery (CR-type) mounted (which had to be removed for baking). Does my 4100 have a battery too?

In the service-manual I did not see one in pictures, nor in partslists, but I do not know how detailed these are.

Thank you.

oldprinter19

[east2100]

All as i can remember HP 4100's formatter doesn't have a  battery.

Yes, you can switch on/off with or without formatter to do engine test.

Formatter is the one which you plug printer cable into.

If you want to try baking you can put the whole metal case (with the formatter together) into it.

[oldprinter19]

Hi helpers,

After some head-scratching I was able to remove the formatter with its case.

(nice construction HP!) and saw the formatter connects to the rest of the printer

by just one connector.

Did the engine test again, and it prints fine again (the test-output sheets).

I noticed the display was off now (will be the formatter board).

So now there is strong evidence the formatter-board is causing the halting of my printer (as in my 1st post)?!

After viewing the baking-videos suggested before, I did some net-searching on mainboard soldering techniques, and

came to pages describing reflow/reball procedures, and reflow ovens used in that.

Even 'how-to-build a reflow oven' pages....

My question now: is this reflow method comparable with the baking method?

As these reflow-ovens seem to give better control (temp.), maybe it would be better to seek for someone who can do this

for me (on my formatter board), as my home oven is old and not very controllable (hardly any temp. indication)??

Related to the resoldering: did HP use leadfree or leadcontaining solders on these boards (which might be important in selecting a correct temperature in reflowing/baking?

Thank you for further information on this.

oldprinter19

[oldprinter19]

As I am searching a replacement formatter board for the hp 4100 printer now, I came on the Net to chinese sites offering hp-formatter boards...

Where HP boards ever made in China (for HP) or are these offers el-cheapo copies of the originals...?

As the wanted board is not available at HP any more, I need some solution for my non-printing LJ4100.

Thank you for reading and a useful answer.

oldprinter19

[oldprinter19]

EDIT:

As guys on a electronics forum over here were rejecting the 'baking method' (maybe 'bake-off method'), I did not want that method as it was described here and there as only a temporary solution, I looked for and aquired a replacement (used) formatter board on the Net, and the printer is working fine again. GOOD.

Now the display is telling me regularly, the printer needs service (due to the number of printed pages), but it still prints nice.

I did read, service is needed every 200,000 pages.

My asking now: how long can I expect the printer to go on (and can I ignore the service message)?

I did see, I can stop that message to be displayed, so I will not be the only one with this plans...

Thank you,

oldprinter

[Repairatrooper]

It is difficult to predict because we do not know the history of the printer. It is possible that the page count came over from the replacement formatter and that may not match the actual page count of your device. We find that the 200K page count is a pretty good indicator of when the fuser needs to be replaced. You can safely ignore as you will know when you need a fuser, or if you start having print defects post back here and we can gladly help you again.