Hp 97 faint printer


Hello HP Museum,
I have an HP-97 with faint printing, what can I do to fix this? possibly a capacitor or resistor change. The printing is variable. Take a look.

Thanks in advance,



If you don't see the pictures here are the links:

Picture 1

Picture 2


The two recommended fixes for this are:

1) Try new paper. You can buy it a most office supply stores or on-line.

2) There is a resistor (R8) on the 97 printer controller board that can be changed to control the print intensity. See page 2-4 of the service manual. From my experiments this doesn't have a huge effect, but some.

Edited: 22 Sept 2011, 11:08 a.m.


Hello Katie,

I have tried different paper and have tried the same paper on my HP-41c printer and printing was excellent so I am pretty sure the paper is not the problem.

I do not own the HP-97 service manual. Can you email me the necessary pages to do this resistor upgrade?




That really does look like the result of old paper to me. I would first try new paper.

It could be a build up of some gunk on the print head I suppose. I have repaired a lot of HP-97 printers and they have all responded well to a good cleaning. I have never had to change the resistor. Take it apart, clean everything and rebuild it. The really good news is the paper appears to be advancing evenly, a common problem that is a bit more difficult to fix.

Rebuilding the printer is intimidating at first but really isn't difficult. Get the technical manual from the museum DVD - it is an excellent investment and not expensive.

Side question: Is there any source of modern blue printing thermal paper?


Hello Dan,

I have tested the same paper on a HP-82143a thermal printer for the HP-41c and it works fine. Could it be that the 82143a printer has just better printing power than the HP-97 and works better on old paper?
I will definitely take your suggestion and try to clean the print head.




Hello Dan,

I have heard that staples sell thermal paper.

How can I clean the print head? How do I get to it?



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