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

[Michael Meyer]

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.

[Namir]

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

[Michael Meyer]

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?

[Marcus von Cube, Germany]

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

[Michael Meyer]

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