HP97 The journey begins

[teenix]

Hi Andy

Thanks for the assist, very appreciative.

The CPU board is operating in "remote mode" away from the calculator and the paper is just sitting in the bare printer so it is a bit loose without the clear plastic screen. I think the paper is moving about a little bit while the head moves. The oscilloscope pixel output looks even and clean.


Well, I got to thinking again :-)

I didn't think much of what actually popped into my head, but on the off chance, I thought why not get out the 97 service PDF and find out the oil points for the printer mechanism. I applied a small amount of oil that you use for hair clippers, nice and light, and allowed it to work its way in. I then cleaned up any residue and tried the printer again.

Immediately, the [ 0.00 *** ] print line doubled in length. I printed about 15 lines and all were exact same length. I reduced the print line length timing in software by 50%, and printed [1.23456789.0] about 10 times and every line was the same length.

I'm not jumping for joy yet, but it would seem that the mechanism needed a bit of oily love. If this is indeed the case, then I will reduce the PWM hardware reference for the motor FWD speed and try it out again.

It would seem that this type of simple printer maintenance is well worth while.

It is a late cold Sunday afternoon in what is apparently the worlds longest lockdown here, so maybe tomorrow. I think a wee dabble in some brown frothy suds might be in order for now.

cheers

Tony