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HP-29C signs of life... any clues as to the cause? - Printable Version

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HP-29C signs of life... any clues as to the cause? - Michael Meyer - 10-31-2008

I bought a 29C from eBay, hoping to finally finish my collection of working Woodstocks. Good and bad news. It turns on, either in regular or program mode, for about a half second before it blanks off.

It will even hold a digit in continuous memory, so it seems it's all working but the power.

Does anyone know if this is a common problem with a single component that needs replacing, or is this a bit harder to track down? Thanks in advance for any insights.


Re: HP-29C signs of life... any clues as to the cause? - Namir - 10-31-2008

What is powering the calculator? The rechargeable batteries or AA batteries? Using the latter ends up applying additional voltage and current that can mess up the calculator's chip set.

Namir


Re: HP-29C signs of life... any clues as to the cause? - Michael Meyer - 10-31-2008

I've tried both. I've read pretty extensively online whatever I can find about the 29C. It sounds as if the memory chips are the most likely candidates for failure, but why would the calculator try to turn on for a moment with the correct display and retention of X? When first powered up, it even displayed "Error" for a short moment before shutting down. All of that looks positive... or is it?


Re: HP-29C signs of life... any clues as to the cause? - Marcus von Cube, Germany - 11-01-2008

Question: How do you feed power to the calc? I'd suggest to charge the batteries externally and not to use the power adapter.


Re: HP-29C signs of life... any clues as to the cause? - Michael Meyer - 11-01-2008

Thanks. I never attached an adapter to the calculator... but that doesn't mean the previous owner didn't. I've asked Randy what he thinks of the symptoms. I have a non-functional 19C (corroded power board from leaking batteries) that could be a source of memory chips if that's what's wrong.

I remember that HP-25's with bad memory chips will turn on, and even go into program mode, but they just won't remember anything. My 29C won't stay on, thus making me wonder if it's a power problem. I have the other Woodstocks, but have wanted a working 29C since I started collecting, so I appreciate the your help!

Michael