HP Forum Archive 14

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HP 67 displaying all 0's Message #1 Posted by Marco on 8 Nov 2004, 12:00 a.m. Hi Everyone, I have an old HP67 that was working beautifully (except the card reader). I wrote a program to make sure it was all working ok and accidentally left it running all night. In the morning when I returned, the HP67 was displaying: -00000000000 00, with some segments brighter than others. I turned it off and on but still the same problem. It now consistantly shows the above when power is applied. If anyone has any suggestions I would be very grateful. I would love to get it going again. Cheers Marco

Re: HP 67 displaying all 0's Message #2 Posted by David Smith on 8 Nov 2004, 4:07 p.m., in response to message #1 by Marco A display of all 000000000 is THE classic symptom of a bad ACT chip (very rare for it to occur in an HP67 though). Only source of the chip is another machine. The ACT chip from the HP21/25/25C/67/97 should work. Can't use the HP27 ACT though.

Re: HP 67 displaying all 0's Message #3 Posted by Marco on 8 Nov 2004, 5:41 p.m., in response to message #2 by David Smith Thanks for your response David, I appreciate your time. I'll look for an old ACT chip, hopefully from a dead HP somewhere (I'm in Australia). Otherwise, I'll have to beg someone on this forum if they have a spare floating around. Do you think the running all night may have fried the ACT? Thanks again. Regards Marco

Re: HP 67 displaying all 0's Message #4 Posted by Albert on 9 Nov 2004, 8:28 a.m., in response to message #3 by Marco Hello Marco, It isn’t a reason of damage to leave your calculator working all night long. You can leave your machine more than 24 hours without any kind of problem, normally. In fact, for instance, after a huge repair in my HP-67 (I changed the lateral PCB –with a Fender guitar shape- that had a big hole in the middle of the lines), I designed and rebuilt a new one. Afterwards, I left the machine running within an infinite loop with the SD-15C Standard Diagnosis Program some days, and no problem. Regards and good luck!

Re: HP 67 displaying all 0's Message #5 Posted by David Smith on 9 Nov 2004, 11:58 a.m., in response to message #3 by Marco I have seen several machines that died shortly after being used for the first time in many years. The problem has always been a chip failure. I suspect that some minor corrosion problem accumulated in storage and the stress of being put under voltage caused it to finally give way.

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