Re: Display on early HP 41C Message #7 Posted by Ion Abraham (New Mexico USA) on 4 Jan 2001, 7:06 p.m., in response to message #6 by John Robinson
John,
Thanks for your suggestion. I opened a second, more recent 41C I'm trying to fix, and I see the clips and all, so I am going to try the procedure you describe, especially because this one has some black graphite-like stuff behind the lens in the display, and one of the leads to the display was desoldered already. This more recent unit never did show anything in the display, despite repeated clear-enter-ons, but I have some hope after seeing the loose lead. I still think more is wrong than just the display, because BEEP does not work either, for example.
What it does do is emit a very loud and very high pitched sound when the batteries are first plugged in (after being without them for a long while). The sound then dies down but a very faint buzz is still audible as long as the batteries are plugged in.
Do you or anyone else know what causes this? I have seen this mentioned by others in the forum archive, but without any explanation.
I guess my foray into restoration is not off to a stellar start, but I wouldn't lose much either way. I bought these two 41C's as broken for not much money, and I got a really nice book out of it, "HP-41C/41CV Operating Manual - A Guide for the Experienced User," a short little book that summarizes some of the more interesting programming and operational basics (for the CX as well).
Still, I am waiting for the CD-ROM set, to see if the service manual has some more useful tests.
Best regards,
Ion Abraham
Albuquerque, New Mexico
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