|Re: This HP-41c doesn't work --- what next?|
Message #2 Posted by Randy on 12 July 2007, 11:53 a.m.,
in response to message #1 by Mark W Paris
Upper posts being cracked - that's usually no big deal unless the screws don't tighten.
The nuts on the lower posts wasn't a repair attempt, it was the original method HP used to secure the logic board to the keyboard. It worked quite well until you removed and installed the logic board several times - at which point the post threads would fail and the nuts would no longer hold the board tight enough to make proper contact. HP did have undersized nuts (they were usually gold in color) for these cases but ultimately they would strip too.
Shouldn't squeezing by hand do it?
No, it usually will not work. The logic board has to make (IIRC) 28 connections to work... and you simply can't apply pressure in the correct places.
The next step, I suppose, is to cut out the middle-man and just go ahead and solder wires between the pressure contacts
DO NOT DO THIS!!! It is absolutely the wrong thing to do. There is NEVER a good reason to do this. It's a horrible mess which makes your 41 non-modular thus preventing any further testing by simple board swapping.
My question is: does anyone know how to check the chips?
Yes, it's called the Service ROM. It's the only way.
I'm assuming the electronics are fried anyway
That is *VERY* pessimistic.
Bottom line: Remove the logic board, clean both sides with isopropyl alcohol and dry well. Re-install and use the nuts to secure the logic board if they hold. If not, you'll need to fashion some spacers in place of the nuts in order to apply pressure to the board. Check the soldered connections between the keyboard and display driver, resolder any fractured joints.
You'll probably find it works...
Edited: 13 July 2007, 2:49 p.m. after one or more responses were posted