HP-97 printer problem

[George Merriman]

I just picked up an HP-97. It works pretty good, except for the printer. It prints, but the results are very hard to read. The top and bottom rows of dots are OK, but the middle of the glyphs are dim. The effect varies from time to time--sometimes I can just make out what is being printed, sometimes it is so dim that I can't. I measured the resistances in the print head, and none seem to be open--they all measure about 11+ ohms.

Can anyone give me some advice? Do I need a new print head? A new printer? a new calculator? Anyone know of a source of parts for this thing?

[David Smith]

Make sure your paper is good. Any original HP paper is well past its prime. Go down to your local office supply store and buy a pack of NCR thermal paper rolls.

Another problem may be grunge on the printhead. It can be cleaned off with 91% isopropyl alcohol. Be gentle as you can damage the tiny print resistors very easily. Also it is easy to crack the print head ceramic carrier when reinstalling the printhead. Make sure it is properly positioned and gently tighten the screws alternating between them so you do not create any unbalanced stresses across the printhead.

Another problem may be the printhead is out of alignment or loose. Or the spring loaded platen that backs up the print line is not properly seated, etc.

The only source of the printheads is another machine.