Re: HP-35 display problems Message #4 Posted by Robin F. on 17 Aug 2005, 6:44 a.m., in response to message #3 by David Smith
I've already cleaned out a lot of green junk (copper oxide?) that was all over the inside of the calculator, maybe that's the problem. I'll try to clean some more, but what exactly do you mean by "keyboard traces"? You mean the traces on the keyboard PCB?
I don't have an oscilloscope, but by using a small loudspeaker with a 5 kOhm resistor I found out that the RCD signal is present, but I heard no "Step" signal (the one from the anode driver to its neigbour). Is it likely that the anode driver breaks in this way, or do you think something else is wrong? If it's just the Step signal, would it be possible to replace it by dividing the system clock or something like that?
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