Need help repairing a hp9120 printer

[Roland57]

I‘m a lucky owner of a hp9100B with 9120 printer. The 9100B is in very good cosmetical and functional state - but the printer needs some repair: I exchanged the paper transport wheel sucessfully. Unfortunately the „printhead“ has been damaged. As far as I see this printhead consists of 7 wires closely spaced to each other. The ends of these wires burn black spots on the metallized paper. Everything worked fine after the repair, but I forgot to tighten the screw that fixes the printhead - the head crashed and is now damaged. What could I use as a substitute ?

Roland

[Roland57]

Hi,

I'm still looking for an idea to rebuilt my 9120-printhead. Here is a picture of a working printhead:

[attachment=6649]

I'm looking for a substitute for the 7 "fingers" and the orange fixture to the left. The contact fingers must have a certain stiffness - therefor a conventional flat contact cable will not work. The whole printhead is 3 to 4 mm wide and approx 10 mm long.

Any idea is highly welcome !

Roland

[Roland57]

Hi,

Meanwhile I was successful to get my 9120 working:

The paper advance roll has been replaced with a silicone tube with 14mm/18mm inner/outer diameter which works perfect.

The old printhead showed mechanical problems and the flat-band cable had severe corrosion and a few interrupted lines: both have been removed.

For the printhead I used 0.35 mm enameled wire. With scotch-tape I fixed 7 wires in parallel like this:

[attachment=6671]

On the print-side (right) the insulation at the 7 tips has to be removed with some adhesives and the 7 pins have to be spaced equally over a span of approx 4 mm. This fits perfectly into the original fixture. To increase the pressure of the soft wires on the paper they must be supported by some tape:

[attachment=6672]

The 7 pins have to be connected directly to the circuit board, leaving the rest of the old flat cable untouched (maybe for a more professional repair in the future).
The results look promising:

[attachment=6673]

AT least for demonstration purposes the printer is in working condition !

Roland

[BobVA]

Nicely done!

[dramsey]

FWIW the printer was not designed to use the metallized paper you might suppose it would, and aluminum oxide ash can build up on the printhead. Since you'll only be using it for demo purposes, it's probably not that big a deal, since the original chemically-treated paper was (AFAIK) unique to that printer anyway, and wholly unobtainable now.

EDIT: Hm. That does look like the correct paper, though.

[Roland57]

(12-14-2018 02:22 AM)dramsey Wrote:  ...
EDIT: Hm. That does look like the correct paper, though.

Yes, thats my last roll of original hp paper for that model and I will be ***very*** cautious to use it only once a year for demo purposes :-)