Any hope for that derelict HP-25?

[acapde]

(11-12-2017 05:46 PM)Benoit Maag Wrote:  Just bought on e-bay an as-is HP-25 with the intention to upgrade it with a Panamatik LP

Unfortunately, the machine was in a much worse condition that I expected (see slide 1)
After an hour with vinegar, Q-tips and an old toothbrush, I could get to a slightly cleaner board (slide 2), but there is still some blue corrosion I cannot reach, and some lines on the keyboard PCB are damaged and cut-off

Is there any hope to get it back to life?
Is it realistic to fix the broken PCB lines with conductive paint (like Bare Paint)?
Should all blue corrosion be removed? Any suggestion as to how to do that?
I damaged one of the feet - what is a good replacement? (eraser cut to size, caulk...)

Please help - Thank you

I fix electronic equipment all the time however I'm not in the business (or pastime) of restoring... I'm making the distinction because the approaches can be quite different. If that were my calculator I would remove all the corrosion as possible (I still see a lot), many times I use rubbing alcohol (+90%) and a toothbrush. Sometimes I use solvents but those are more aggressive... in any case, make sure that the plastic exterior parts don't get in contact with any alcohol or solvent of any type... make sure it stays in the PCB. You might need to do some scratching as well, I use a very small flat screwdriver for that (go easy to minimize collateral damage). To connect traces I just use wire-wrap (solid wire, 30 AWG if I remember well) and solder it in a clean part of the trace (before and after the cut), this part requires some skills, I use the soldering iron since I was a kid so it's kind of natural for me to chose this option.

My biggest concern would be the keyboard contacts, have you checked that part? I would evaluate that before starting if possible... you may use a DMM before breaking the rivets

My 2 cents... good luck with your project.