HP-41C/LCD Crack



#10

I was thinking of buying this old HP-41C to have as an extra - even though the LCD is cracked. Any chance this defect could be repaired by an end-user? Could you just take the lense off?


#11

It looks like it's just the plastic panel over the LCD that's cracked and not the LCD itself. The problem is that to get access to it from the back you'll have to remove the keyboard/display assembly, which is held onto the topcase with 51 heat stakes. You'll have to remove them in such a way that you can re-attach them later to complete the repair. I"m working on a way to do that for a CX with a bad Alpha switch I want to fix. (anyone with any help on this would be appreciated)

Another alternative is to remove it from the front and drop a new one in. You could probably make a decent one from a piece of plexiglas.


#12

You may not need to remove the keyboard if you desolder the display contacts from the inside. Doing this, you can remove the display and replace the panel.

#13

What's wrong with the alpha switch?


#14

Quote:
What's wrong with the alpha switch?

I don't know what's wrong with the underlying mechanism but it appears completely collapsed; the 'ALPHA' side of the rocker is unsupported and rests low. And of course there's no electrical response.


#15

Quote:
And of course there's no electrical response.
That doesn't make sense. Initially, my response would be that the snap dome fractured and is that is why is it flat - but it should still register when pressed. Wierd.

Is there any click or resistance felt at all when pressed?


#16

Quote:

That doesn't make sense. Initially, my response would be that the snap dome fractured and is that is why is it flat - but it should still register when pressed. Wierd.

Is there any click or resistance felt at all when pressed?


No, none.

#17

Re: the unit shown. While the window can be replaced, it is *NOT* an easy task for many reasons.

It is the later halfnuts that have an integrated LCD/Keyboard/Proceesor in which the window cannot be replaced without serious surgery. That work will leave you with a less than perfect result.

The unit shown is a fullnut in which the LCD can be removed as a seperate module.

Once the LCD has been desoldered and removed, the window can be removed from the back. It is made of 1/16" thick injection molded crystal polystrene and is somewhat brittle which is why they crack. If the old one doesn't snap out cleanly, you've got a mess on your hands. Making an exact replacement is almost impossible by hand, the easiest method is to salvage one from an otherwise dead unit. Installing can be tricky without doing cosmetic damage.

IMO, unless it sells for $5 and the crack doesn't bother you, save your money.

Edited: 23 Aug 2006, 3:40 p.m.


#18

I think that it went for around $50.00 including shipping - a little much - especially considering the lack of confidence I have in my soldering skills. ;-)

I found an interesting deal instead that I picked up - not great - but I think a fair deal. It was for a 41CV in like new condition, with the X Functions, HP41 Advantage and Math/Stat packs for $150.00. You never know with these auctions exactly what "like new" means. ;-) We'll see...

Now I'm looking for an early/mid 80s vintage 12C. I just don't like the keys on the newer ones... 12Cs seem to be in a little more plentiful supply - though the old ones are a little harder to locate...


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