contactor damage. How bad?

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contactor damage. How bad?

Postby eroeder » Sun Apr 03, 2022 10:10 pm

How bad is the corrosion damage to the battery contacts? Unit powers, but not sure long term implications. Here was the original (first pic), then I cleaned with isopropyl alcohol (second Pic). Anything else I can do to improve?
Before cleaning attempt
after cleaning attempt
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Joined: Mon Mar 28, 2022 3:16 pm

Re: contactor damage. How bad?

Postby Garth » Mon Apr 04, 2022 12:44 am

If it's from leaking alkaline batteries, a Q-tip moistened with white vinegar will clean it up. Hold the calc oriented such that if there's any running or dripping, it'll run or drip out of the calc, not in. If too much of the material is gone, that flex circuit is available brand new to replace the old one. It might be good to buy one to have on hand, but don't open the calc to put it in as long as it doesn't seem necessary. The reason is that there are posts that tend to break when people open it. There are ways to repair them, but why not just avoid the situation for now if the flex circuit is still good so far.

Replacement: ... _Block.htm
video on how to install the replacement:
forum topic for updates and info on fakes:

These links are from the HP-41 section of the links page of my site, linked in my signature line.
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Re: contactor damage. How bad?

Postby floppy_stuttgart » Wed Apr 06, 2022 9:47 am

I had such a situation: my suggestion is, depending of where you are (EU, US..?) find a recommended repair to make it working again (however a cleaning is good anytime as a first try; perhaps with aceton on a ear cleaning stick).
My story.. a good old CV was sent to repair..
a) first time they changed the flex (what we see on your picture)
b) it still did not worked properly
c) I sent again and the board was cleaned again
d) since it was still not working properly, I sent for exchanging the board (exchange cv board since the keyboard and the LCD were fine).
Since the parts are in plastic, with ageing its becoming difficult to repair (opening, screwing) without cracking anything.
And at the end: that CV dont accept the Nov64d from diego. But its fine for programming with standard modules in it, ok with hp-il etc.
So, good luck. I will cross the fingers for you.
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Re: contactor damage. How bad?

Postby BillBee » Fri Apr 29, 2022 3:24 pm

Hello There,

My rule of thumb is to not take a 41 apart unless it needs it. Garth explained it well.

The recommendation of a gentle cleaning would be my first go. IIRC the middle two terminals actually put the middle batteries in series so worst comes to worst copper tape will work wonders making that connection. The tape can also be tried if one of your outer connection are bad.

Just my thoughts,
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Joined: Tue Apr 20, 2021 2:06 pm

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