HP 41CX shut down



#5

My HP 41 CX shuts down in less than 30 seconds. It used to shut down in 8 minutes or something but now it shuts down in between functions. All info is there when I turn it back on but it is a pain to turn it back on all the time. Even with fresh batteries. Any ideas?


#6

Brent,

I had the same problem with my 41CX (it was a fullnut). It would shut off in just under 15 seconds after the last keypress.

I dug very deeply into this but was never able to really nail down the solution exactly. The problem is related to the "sleep" mode of the calculator, which is controlled by the LCD display driver (trust me). I have seen several other people post with the identical problem, so it must be an inherent weakness of the design.

One quick and dirty solution is to XEQ "ON" when you first turn on the calc. Of course, you need to remember to turn it off, or you could use up a bunch of N cell batteries.

The more complex solution, and one which unfortunately led to the demise of my CX (sob) is to try to repair the hardware problem creating the "quick off". If you are comfortable opening the calculator, I would recommend looking at the metal tabs which connect the LCD display driver to the main board. Use a sharp pointed object (like a dentist's pick) and a magnifying glass to see if any of the connections have come loose. If so, repair them with a fine tipped soldering iron. Just do a better job than I did .... I apparently damaged something in my effort to find the problem.

Good luck

- Ed


#7

Ed,
Thanks for the info. Is there any information on the procedures for opening a 41? I'm new to the site and hadn't seen it but figure somebody would have this. Just don't want to break anything unnecessarily. I'll keep looking. Thanks again.


#8

Brent,

Yes, right here on your friendly MoHPC is the information you seek.

First, you should read:

http://www.hpmuseum.org/disasm.htm

Specific to the 41CX (really applies to any 41C fullnut):

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cgi?read=2

One of the contributors to this forum (Randy Sloyer) also repairs calcs:

http://www.fixthatcalc.com/

- Ed


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