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HP-41 Permanent broken Post Fix


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Post: #2
05-17-2011, 10:35 PM
aj04062 Offline
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Up for review is my permanent repair to fix your ailing 41.

As some in the forum know, I had posted the question why my two 41CVs were acting strangely. POSTS. Nothing more, nothing less. Well the following is my permanent cure for one. It's posts where helplessly cracked beyond repair. What I resorted to were two 4-40 brass standoffs about .25-.27 inches long x .1875 OD.

Finished height above board = .200

The old post was milled off with a .1875 end mill and bored down about the thickness of the board (.070)

They were then epoxied into place.

Now proper torque can be applied to the 4-40 screws and the unit behaves as it should. Hopefully it will last another 29 years!


Edited: 17 May 2011, 10:49 p.m.

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Post: #3
05-17-2011, 11:54 PM
db (martinez, ca.) Offline
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That's a very elegant solution. I just lazy out and slip slightly too-tight springs over the split plastic. It works but not as prettily as your brass fittings.

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Post: #4
05-18-2011, 06:04 AM
aj04062 Offline
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These ones were shattered and sheared off at the board. No spring would have helped them!

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Post: #5
05-18-2011, 01:46 AM
Ángel Martin Offline
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Brilliant solution, and great pics!

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Post: #6
05-18-2011, 02:11 AM
Didier Lachieze Offline
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Great solution! Would you have some spare standoffs as I just have one 41C with the exact same problem?

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Post: #7
05-18-2011, 06:03 AM
aj04062 Offline
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I should have a few next week. I requested a sample lot from Keystone Electronics. They will need to be faced back from their .375 length to .25-.27. Drop me an email off-line for info.

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Post: #8
05-18-2011, 09:53 AM
Monte Dalrymple Offline
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Excellent solution. I've got a couple of machines that can use this fix. But isn't the .1875 OD a little too big for the holes in the processor board? I thought that the posts were 4.3mm (0.169) and the holes in the processor boards were 4.5mm (0.177). Did you have to slightly enlarge the holes in the processor board?

Monte

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Post: #9
05-18-2011, 10:22 AM
PeterP Offline
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aj, can you post a link with what exactly you ordered, I think there might be a few people (including myself) that want to try your truly elegant and well working solution.

Thanks!

Peter

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Post: #10
05-18-2011, 12:04 PM
Raymond Del Tondo Offline
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I'm interested in a couple of these brass cylinders, too.

Are these available in the suitable legth for the upper posts, too?

Is the screw thread already there?

Thanks

Ray

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