HP Forum Archive 20

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HP-41CVs will not turn on Message #1 Posted by aj04062 on 14 May 2011, 10:42 p.m. So I have rebuilt and cleaned two Fullnut CVs in recent days. Both are exhibiting behavior that is documented on the Museum, but I thought I'd ask again as I cannot seem to find the solution in the posts. Steve's Post One calc behaves as such: Once on, will turn off normally with on button. No matter how many times I press on by itself, the display will not come on. However, if after turning off, I press on ONCE and then press BACKSPACE, ENTER, ON the calculator will ALWAYS come on. If I try that sequence after turning off, it will not turn on. If I do that sequence twice, it will turn on. I cannot get the calculator to reset via BACKSPACE, ON Once the calculator is on, it seems to work fine. HELP!?

Re: HP-41CVs will not turn on Message #2 Posted by Frido Bohn on 15 May 2011, 7:42 a.m., in response to message #1 by aj04062 Lastly, I had similar problems with a halfnut HP41CX. Eventually, all problems were resolved with a reset. A simple achievement of MEMORY LOST in the display did not help. Try this link.

Re: HP-41CVs will not turn on Message #3 Posted by Randy on 15 May 2011, 1:30 p.m., in response to message #1 by aj04062 Short the 470 uf cap on the processor to reset the unit to all defaults. If the problem persists, my guess would be a bad rom or D/S IC. Swap processor board to verify. If it is a bad board, it would be almost impossible to troubleshoot without a service rom.

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