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Joined: Jan 1970
I had one HP-12c (Made in Malaysia) with this problem. This row of keys, in this one-chip unit, is connected to one CPU pin. This CPU pin had a bad solder. Fixing was just a matter of carefully heating this pin.
1234
Posts: 883
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What's the serial number?
Posts: 137
Threads: 11
Joined: Jul 2006
Hi Pierre
The symptoms sound very familiar as I had a similar problem due to one pin on the CPU not being soldered to the board. I can do no better than refer you to this thread:
http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv013.cgi?read=34793
where I found some very good advice which enabled me to fix my 12C which is still going strong.
As Luiz would say....
Success
(and let us know how you get on)
Posts: 64
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Joined: Apr 2010
Hi all,
I've been deeply impressed to receive, within 50 minutes, four wise answers to my post.
Thank to you, this HP12c is now repaired. One other saved !
It is indeed a Malaysian unit, serial Number 3635M01102. The faulty pin was the one pointed out by Randy Sloyer : second from the bottom of the right row. It was not possible only visually to see that this pin was not perfectly soldered on the board. Even with a multimeter I had some doubt, because when you test the pin, you press it, enabling the contact !
The contact was soldered again by pressing the pin with a small screwdriver and making melt the solder with the iron.
I was surprised not to find in the calculator the famous voyager's polycarbonate wrapping.
Thanks again
Pierre Brial