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Bad HP41 display? Shows @'s and whistles
03-09-2017, 10:13 PM
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Bad HP41 display? Shows @'s and whistles
Hello everyone,

I am hoping someone else has encountered the display problem I currently have. While trying to fix a CPU zebra connector problem, my 41CV began showing all '@' characters in the display, while the buzzer emitted a high pitched tone. I swapped out the zebra connector with another known good one without effect. Thinking perhaps the CPU was damaged, I put a different board into the case and got the same exact behavior when putting the batteries back in.

With two different CPU boards and two different zebra connectors producing the same bizarre behavior, I decided to put one of the CPU boards into another working case. The CPU worked perfectly, leaving me to think the problem must be with the display. The I/O connector is in near pristine shape and worked fine earlier in another case.

As suggested in another post, I did press lightly against the display connector pins to see if any might be loose. Before going at the solder joints with an hot iron (yikes!), I wanted to check to see if anyone has seen this display behavior before. The display failure, if that is what it is, did not happen immediately. There was a short period when I would get garbage in the display and occasional tones each time I put the batteries in, which reinforced my original thought that the zebra connector was bad.

Sound familiar to anyone?
~ Mark

Remember kids, "In a democracy, you get the government you deserve."
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Bad HP41 display? Shows @'s and whistles - mfleming - 03-09-2017 10:13 PM

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