[PLUG-TALK] Hardware tinkerers: HP printers ...

Keith Lofstrom keithl at kl-ic.com
Tue Sep 4 15:21:49 PDT 2018

On Tue, Sep 04, 2018 at 07:47:57AM -0700, Rich Shepard wrote:
> I'm replacing my HP 2550C color laser printer. It quit printing color when
> I replaced the yellow (and black) toner cartridges; now prints only black. 

Related to Rich's printer:

I am fond of HP2605dn color duplexing printers; sometimes
they were on sale for less than the cost of a set of
cartridges.  They came with full cartridges, I checked.
I stockpiled many printers, and recycled them when they
acted up.  I kept the paper trays, so I have special trays
set aside for envelopes and A4 european paper.

Over time, the red and blue fade, even with new cartridges.
The reason is that the laser/mirror assembly is next to
the fan, which circulates air through the toner cartridge
compartment.  Leaked toner ends up on the mirrors.  Red
and blue mirrors are face-up inside the assembly.

So, labor day weekend (and into this morning) was partly
spent finding the service manual online (300+ pages PDF)
and finding instructional websites for accessing the
laser/mirror box, buried deep under a nest of panels
and cables that must be removed and disconnected.

I cleaned the mirrors very gently with camera lens paper
wrapped around a cotton swab.  The problem is getting 
every last little bit of dust and lint.

I successfully restored three of the printers to full
working condition.  Sharp colors, perfectly aligned.
One deployed, two spares; those should last me another
decade or two.


I also sorted through ALL my accumulated spent or mystery
cartridges.  I recycled the leakers and streakers.  Some
cartridges fail to register, vaguely resembling Rich's
problem;  there is a switch deep in the service menu for
that, because sometimes the contacts to the chip on toner
cartridge fail. 

The service menus have ALL SORTS of options, stuff like
"hold down these two buttons for 15 seconds during and
after power on".

I don't know what the 2550C has for service options;
perhaps the manual is not available online.  My guess is 
that service information for newer printers hasn't leaked
out to the public yet.  Or that the cartridges aren't
refillable or replaceable by trustrworthy knockoffs.  Or
that the capacity is low and the cost per print is high. 

I do know that these ancient HP2605s have worked for more
than a decade.  I can still buy old-stock new repair parts.
A printer store owner recently told me that all the whizzy
new printer features (wireless! facebook pages!) are more
important than their three year service life and high cost
of consumables.  I don't go there anymore.

In the current political climate, we may lose access to
printers made in China; trade wars work both ways.  So,
after a year or two of denial, there will be a few years
of frantic worker training and factory building in the US,
as we attempt to reverse decades of off-shoring.  India,
Argentina, and other countries attempted this after World
War II, and their economies flatlined for decades.  We are
not immune; repair may be essential to national survival.


So ... consider learning how to repair the gear you have.
If there are other thrifty, prudent people on this list,
let's gather together and scheme about repairing our stuff
for approximately forever.  Perhaps that should include
setting up an agile and REPAIRABLE 3D printer, so we can
make replacement parts as well.  Not sure what to do for
raw toner, and soft parts like gaskets, wiper blades, etc.

Perhaps we can bypass the cartridge chips with printer
firmware hacking.  While we are at it, we can also hack
the disturbing "yellow dot printer ID" function that makes
printouts traceable by law enforcement.  There may be laws
against all of this, but laws are stored on computers now,
so we can hack those, too.  :-)


Keith Lofstrom          keithl at keithl.com

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