82143A and 82162A printer mechanisms interchangeable?

[Dave Britten]

I've got an 82162A (HP-IL) printer that is about 99% working, but for one reason or another, the bottom row on the print head doesn't really register on the paper all that well. It appears to be uneven pressure against the paper, though I can't tell if it's due to a misalignment in the head itself or the platen. I took the head out and cleaned it with a little alcohol, and I can get the bottom row to print if I fiddle with the platen a bit and align it better with the head.

Is it possible to simply swap the whole mechanism with that of an 82143A? I noticed that the optical encoder on the main shaft is a different design, so wasn't sure if they're 100% compatible. But if that's an option, I could just exchange the mech with one from a spare 82143A that produces more even printouts.

[Paul Berger (Canada)]

I just looked at my 82143A and one of my 82162A printers and if yours are the same as mine I would say no. The sensor on my 82143A is a basket like extension of the pulley on the lead screw with a reflective mode sensor mounted on the print assembly. The 82162A has a chopper wheel on the other end of the lead screw and the IR led and phototransistor sensors are mounted on the circuit board on either side of it. It would appear the the only difference is the lead screw and sensor arrangement every thing else is the same. I have used mechanical parts from a 82143A to repair a 82162A before. I have even used the frame of the printer mechanism to repair printers in 97s.

Paul.

[dmh]

The 82162A could print barcode as it allowed for no line spacing and the 82143A couldn't (always had a space between lines) so there are definitely differences.

[Dave Britten]

(03-18-2021 10:37 PM)dmh Wrote:  The 82162A could print barcode as it allowed for no line spacing and the 82143A couldn't (always had a space between lines) so there are definitely differences.

Okay, then I won't risk burning up a good printhead from my spare 82143A by transplanting it. I'll continue fiddling with the platen and see if I can get more uniform pressure. It's only the bottom row that seems to be affected.

[Paul Berger (Canada)]

The platen has a groove in the back that fits over the piece it is mounted on if it is not in place you will get poor print. You might want to check to see if you have a weak element on the print head if you don't find anything amiss with the platen. To unplug the head cable slip a thin piece of plastic in between the cable and the contacts, I use pieces cut from PET packaging, and pull the cable and plastic out as one. Measure the resistance of the each element to the double wide common, they should all be about the same. You will not that the end of the cable is folded over, to reinsert put you piece of plastic inside the fold and ease the cable back into the connector.

Paul.

[Dave Britten]

(03-19-2021 12:35 AM)Paul Berger (Canada) Wrote:  The platen has a groove in the back that fits over the piece it is mounted on if it is not in place you will get poor print. You might want to check to see if you have a weak element on the print head if you don't find anything amiss with the platen. To unplug the head cable slip a thin piece of plastic in between the cable and the contacts, I use pieces cut from PET packaging, and pull the cable and plastic out as one. Measure the resistance of the each element to the double wide common, they should all be about the same. You will not that the end of the cable is folded over, to reinsert put you piece of plastic inside the fold and ease the cable back into the connector.

Paul.

Good ideas, thanks Paul. I forgot about that little groove behind the platen. It looks pretty centered, but looks can be deceiving. I'll check with the multimeter if that doesn't help.

[anetzer]

(03-18-2021 10:37 PM)dmh Wrote:  The 82162A could print barcode as it allowed for no line spacing and the 82143A couldn't (always had a space between lines) so there are definitely differences.

I remember that back in the days there was a Do It Yourself kit to modify an 82143A so that the line spacing was disabled. To that end a further switch was added to the chassis, alongside the MAN NORM TRACE selector which only served to shorten the paper advancing between lines to the exact height of the print head.

I actually used one of those to print barcodes (in landscape mode, actually). Special paper was available to achieve a higher contrast and placing the thermal paper under a coloured transparent foil would also help...

[dmh]

(03-23-2021 09:06 PM)anetzer Wrote:  

(03-18-2021 10:37 PM)dmh Wrote:  The 82162A could print barcode as it allowed for no line spacing and the 82143A couldn't (always had a space between lines) so there are definitely differences.

I remember that back in the days there was a Do It Yourself kit to modify an 82143A so that the line spacing was disabled. To that end a further switch was added to the chassis, alongside the MAN NORM TRACE selector which only served to shorten the paper advancing between lines to the exact height of the print head.

I actually used one of those to print barcodes (in landscape mode, actually). Special paper was available to achieve a higher contrast and placing the thermal paper under a coloured transparent foil would also help...

Now that you mention it, I remember hearing about this mod too.

Do you have a reference? So you actually did it?

[anetzer]

(03-25-2021 12:50 PM)dmh Wrote:  Do you have a reference? So you actually did it?

I do not think I can dig anything up. It was not my printer, but one I had access to.

I do only remember that a complete set of all the parts plus an installation instruction could be ordered and installed.

One had to cut an opening for the extra selector switch into the upper case. What really awed me back then that somehow the supplier had come up with a two way switch that was identical to the ones HP installed.

So - apart from the choice of places where it could be located in the upper shell - it looked almost like factory installed....

Function was self-explaining: in one position the printer worked normal, in the other it reduced paper advance so that there was no spacing between the lines. Quite simply and effective.