Message #5 Posted by Steve (Australia) on 14 Sept 2000, 7:15 a.m.,
in response to message #4 by db (martinez, california)
OK, the reason I suggested using the ON instruction and leaving the calculator sit there is that the
lockups may be caused by the action of pressing the keys twisting the calculator, or somehow moving
If the calculator is content to sit there without being touched then this is some evidence that the cause is
something mechanical. (like broken posts, or a broken wire, etc.)
I would also try to cause the problem by pressing the PRGM, ALPHA, or USER keys firmly, or pressing
other keys firmly. Then I would pick up the calculator and see if twisting it causes problems.
If these things DO cause the problem, then I'd pull it apart and look for the common problems...
Oh, and with the serial number 1939A00407 (which means 407th HP41 produced in the 31st week of
1979) there is a possibility that this calculator has ALL bugs. This makes it (potentially) a rather special
To test this, enter
SF IND 00
if this results in the BAT annunciator displayed in the display, then you have a bug 3, and that generally
indicates you have all bugs.
Bug 3 was removed in the FDE ROM revision that was installed in serial numbers 1936 to 1952, but
the older DDE revision exists in some 41C's up to serial number 1940 (1926 is the earliest).
Even if you can't get it to work perfectly, you may find that it will fetch a good price on ebay -- possibly
enough to get you a CX.
I purchased a 41C from a guy in Canada quite a while ago that had all the bugs. I found that when it
arrived in Australia it had rather obscure symptoms -- none that required removing the batteries for
several hours -- but it certainly did turn itself off at odd times. Mine was a rather simple job to fix, and
it is now my favorite 41!
Oh, and mine is 1937A002XX -- only 2 weeks younger than the 41 in question. Which rases the question, who has the earliest calculator? I've left you guys more than 11 weeks to beat me by.