HP-41 HP82143A printer repair.

[Papymouzot]

Hi everyone,

I have taken maybe a couple of months ago a big box from the basement, inside HP-41 fullnut (dead) card reader, lots of cards with lots of programs. Lots of manuals, some modules and a printer. Missing : a 41-cv, it’s battery, lots of modules. I don’t know where they could be ??

I was like a kid… a lot of memories from 1980’ when I was studying and enjoying this wonderful calculator. I wished to be able to read the programs, print them if at all possible and check what I was able to do back then, when I still had a brain ! ??

I purchased from a very nice guy in the USA a 41cx half nut with some modules (x-memory, advantage, math/stats and games…

Tried my card reader… malfunction ??
Bought another one on EB … card err bought another one … card err
Learnt about the gummy wheel issue and attempted to repair them. One still gives malfunction (my original one) and the one now works… the other one still card err

I tried also the printer. It gets recognized by the 41 but does nothing… Somebody told me I needed a good working battery pack in order to be able to print… purchased 4 NiCd from AE and rebuilt the pack two days ago… piece of cake after having rebuilt the 41 battery pack…

So, new batteries, fully charged… tried to print… printer error, tried paper advance… nothing…

Ok, let’s open the beast.

Amazing… dust in it… I tried reading the service manual, a shame the pictures are so bad quality…

Removed the motor, tested it… it worked… yes
The little belt was in good condition (these products were really great quality back then !! )

Ah ! The axis with the two wheels which are on each end didn’t want to move. So I cleaned these two wheels which are not anymore 100% round after 40 years in a cardboard box. The paper advance mechanism now worked.

I lubricated the worm gear, and removed the print head to clean it… good idea, it was filthy.

I tried turning the printer on… this time the head moved and the mechanism to pull the paper wanted to work but the paper got stuck… I tried to understand where and why ? The paper stopped at the print head position

I thought that I didn’t put the printing head back in place properly… I then removed the head and tested again…. The paper stops again, right at the limit where it is aligned with the little piece of fabric (Teflon ?) (without the head)

I stopped there, thinking I betta ask for advice on the forum.

Is this piece of fabric supposed to be glued on the copper part ? Mine isn’t.


Any idea why the paper stops there ?

I look forward to reading your comments !


Charles