HP-2673A printer

[dramsey]

I just acquired one of these from TAS for a song. The printer works perfectly-- well, almost.

It's a thermal printer that uses standard 8.5" thermal paper. The printhead moves across the paper to print-- that is, it's not a line-at-once printer like some of the other old HPs.

There are two problems:

1. Every time I power the printer up, it beeps and ejects a good foot of paper. That's annoying.

2. The print head doesn't seem to be making good contact with the platen. The platen is a plastic bar that serves as the back surface for the paper-- the thermal paper moves between this platen and the print head. But print is sketchy and broken because the head isn't making firm contact with the paper, because the platen isn't pressing against it from the back.

I can improve the print output by pressing on the platen, so I know this is the problem. But the platen is a "loose piece" that's lightly held by metal clips; there's no spring or foam or anything to provide any kind of light pressure. Right now the platen is very loose and can be easily moved with a fingertip.

The platen is part of a pivoting assembly that includes the tear bar and some idler rollers. It's easy to disassemble (which I have) but there doesn't appear to be any way to get better pressure (the print head doesn't seem to be adjustable). The pivoting assembly shows signs of having been taken apart before so it's possible there's something missing.

Hopefully someone here has some experience with this printer and can offer some advice...

[Mark Hardman]

(03-07-2015 06:52 PM)dramsey Wrote:  Hopefully someone here has some experience with this printer and can offer some advice...

Documentation for the 2673A printer--including the service manual--can be found at the Australian HP Computer Museum:

2673A - Documentation

HTH

[dramsey]

Thanks, Mark, but I already checked all that. There's nothing in the user manual or the service manual covering this.

[Paul Berger (Canada)]

Does it make a clicking noise as it prints? These printers have a solenoid that separates the print head from the paper when it is indexing, so every time it does a line feed it should click, it may be that this solenoid is not operating or is gummed up. You probably won't find the location in the service guide as it seems that the print mechanism was replaced as a unit.

As for the skip on power have you checked to see what is set in the power on configuration? Auto-page mode seems like it might cause that.

[Dave Frederickson]

When all else fails, take it apart and put it back together. Print head removal and replacement procedures start on p. 6-8 of the service manual. This will ensure, at least, that the print head is installed correctly.

Regarding issue 1, it sounds like the printer is positioning the paper at the Top-Of-Form. Did you run all of the self-tests and check/reset the printer's configuration per section 3 of the CE manual?

Dave

[dramsey]

I can't check the printer settings since they're printed out on paper, and the print isn't readily readable right now. But the top-of-form thing sounds likely.

The printer is moderately noisy but I don't hear a click at EOL, nor does the print head seem to move when the paper advances. This may well be the issue! I shall investigate.

[dramsey]

It is indeed a sticking printhead unloading solenoid. A metal rail runs the width of the paper and lifts the printhead at when the paper is advanced. It sticks when the solenoid fires.

Not sure _what's_ sticking yet, but the print is sharp and clear when the solenoid's in the "out" position. Will work on this more tomorrow.

[dramsey]

OK, cleaned up and everything's working fine. The toothed drive belt for the carriage, often a problem with these old printers, was fine.

The "ejects a foot of paper on power-on" problem was the paper setting: the printer can be configured to use either fan-fold or continuous roll paper (in other news, fan-fold is a thing). Setting the printer to use continuous roll paper killed this annoyance.