Repairing HP41C



#6

Does somebody tried to replace zebra connector by a plane cable soldered to contacts?

Do you know how can i do more presure in lower posts? I think the problem is in contact between keyboard and main board.


#7

Hi;

there is a way to completely replace broken posts, and I used the tecnique in at least three HP41 fullnut, but recovering existing, loose ones is a lo better and safe. Some guys use thin plastic slices and glue to dissolve the slices inside the posts holes. Then they drill it thin enough to allow a new thread to be "made" with the screw itself.

You can also try to solder the mainboard to the keyboard. It has also been done, look here. I just warn you that this is a one-ticket trip. Once done there is no way to get back. Both mainboard and keyboard golden plated contacts will never be able to hold zebra connectors again. I'd use this technique as the last shot ever.

Many guys in here mentioned that one can buy standard, comercialy available flexible zebra connectors and cut them to fit anywhere. I would like having the chance to find and buy these connectors for testing, because they seem to be the only way out in these cases, I think.

If you go for soldering, think you will not be able to use the mainboard in another calculator OR use another mainboard in your unless you solder them again.

Success.

Luiz C. Vieira - Brazil


#8

The calculator is now operational. I don't know how i solved the problem.

I've removed again the display and i've remove the display clips from the edges. After this i mount everithing and now is operational.

There is only a little problem: if i press on the calculator near the display, the character contrast is very low. Occurs the same when i press the keys ON, USER, PRGM and ALPHA. Do you know how can i solve it?

Regards from Spain


#9

... since the day I bought it. The bottom edges fade a bit when pressing any of the four "toggle" keys, meaning ON, USER, PRGM and ALPHA. I would not care that much: mine is about 20 Y.O. and works pretty fine after being rebuilt about four months ago. It laid down with internals spread inside a shoes box for more than eight years before being rebuilt.

I'm glad you made it, i.e., "it" made it.

Happy calculations.

Luiz C. Vieira - Brazil

(in time: have you disassembled the LCD assy when you first opened the calculator? I remember I mentioned that in a previous post of yours and I don't remember if you answered. I also remember I mentioned this is somewhat risky. Would you describe your experience, please?)


#10

The first time i opened the calculator i didn't disassemble the lcd. Later, because the calculator did not work, i disassemble the lcd and now everithing is ok.

Regards


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