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Hp 41CX only displays something when pressed on
11-04-2019, 01:11 AM
Post: #5
RE: Hp 41CX only displays something when pressed on
Some people probably have a lot more information with this than me, but I will chime in anyway with some random information that hopefully will cheer you up a little bit.

First of all, there was a post back where someone replaced the bottom screw posts completely. I think using some metal piece and gluing it in. I could be wrong, my memory is fuzzy. It think metal/machine screws were used on those. So that should be fixable. (I do not have a link to that post at hand, sorry about that.)

The plastic on the HP-41 can be welded as it seems to be styrene. You can use the same way plastic modellers use, a liquid solvent. Basically you take some on a small brush, apply in the crack/gap and let it seep in using capillary action, wait 3-4 seconds (any excess will evaporate, but the liquid in the gap stays, softening the edges), then press together and hold (the longer the better). It works best if you can use some means of maintaining pressure on it for quite a while. A weld like this, if done in a perfect way is just as strong as the plastic itself. You need to put the pieces back to where they used to be (to get the best fit). I fixed the upper screw hills this way on mine (the ones next to your broken battery contacts) this way. I am not sure how fixable your parts actually are in practise, as the area to glue is so small and it is probably hard to put proper pressure on it too. Is it really needed? I had some small piece coming off mine around that area and it seemed to work fine without it. Maybe I glued in the thing it was supposed to position, I cannot remember and I am not going to open it to check...

If I remember correctly I welded one of the lower screw posts on mine, which was cracked by letting the solvent seep into the crack and then used a tweezer/clamp to press it together while it set. Then I used one of the screws Monte offers in the repair kit sold with the 41CL.

I had a plain 41C that was left without batteries for a week and it retained the memory when the battery was put back in. Other models with more RAM (and possibly timer chip) may not last that long. The timer chip seems to take every excuse it can find to reset itself, while RAM is less sensitive.

If you cannot make USER key work, a work around is manipulate flag 27 (CF and SF). At least that makes it possible to enter and leave user mode.

You will need to make the screws hold it together, otherwise it will not function properly. Monte mentioned that he uses rubber bands as a temporary means to hold it together for testing.
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RE: Hp 41CX only displays something when pressed on - hth - 11-04-2019 01:11 AM

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