Display goes blank

Everything about 41C 41CV and 41CX Hardware

Display goes blank

Postby FrostbiteFrank » Fri Oct 23, 2009 12:40 am

My trusty 41c started freezing up a couple of weeks ago. I figured that after 30 years it was due for pasture, so I put it away and bought a CX on ebay. It turned on once, then the display went blank. After a week of trying to coax a number onto the display I sent it back. I just bought a CV and it's doing the same thing (blanking out). Having a 2nd one also lose its display has made me wonder if it's an environmental factor. It's the same location that has worked for years, so I don't think the problem is ambient electrical fields. What else could cause 3 calculators w/ good batteries to stop displaying?
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Re: Display goes blank

Postby Klaus » Tue Oct 27, 2009 7:35 pm

Are you 100% sure that your batteries are good? Did you put an application module in all of them? Did you use the same battery holder (or rechargeable pack)?
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Re: Display goes blank

Postby FrostbiteFrank » Wed Oct 28, 2009 2:15 am

Yes, I'm sure that the batteries are good. I have a 2nd 41C and it works fine with the same batteries (which, incidentally, were purchased 8 days ago in a sealed package).
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Re: Display goes blank

Postby Klaus » Wed Oct 28, 2009 12:52 pm

I never heard anything about environmental factors causing that. I have used a HP-41CX in many environments, ranging from cold to hot, from dry to humid (up to 95%). Also, I haven't heard of any problems that other users had.
This won't help you, but these problems are uncommon for the HP-41C series.

Well, now I'm just thinking about the coconut-series that has rectangular display edges. This series is a bit more sensitive to mechanical stresses, since the connection between the PCB and keyboard/display depend on pressure. But they don't fail simply because of transportation, mostly it is because the previous owner has opened the case and cracked the plastic posts.
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Re: Display goes blank

Postby FrostbiteFrank » Wed Oct 28, 2009 6:41 pm

I used to be a surveyor, and numerous times I encountered problems with the display blanking out when working under high-power transmission lines (mostly 230KVA). A number of other people have encountered this difficulty too, so it appears to be endemic to the 41 displays. After about a half-day away from the force fields the display returns. This is not what happened with the ones I just tried - one displayed once, then stopped; the other one comes on for 1/2 second and then goes blank. I sent both back, but would be interested in a solution that I could pass back to them.

Predecessor problem:
My original 41C (the old "coconut" as you call it) works fine for a while, but then freezes up with the number displayed at time of freeze-up. This happens randomly - sometimes a day apart, sometimes 5 minutes. If I remove the batteries for a few minutes it comes back to life (with a "Memory Lost" display), but soon freezes up again. Any experience with this problem? It's enough of a nuisance that I've been trying to replace it for the last 10 days.

Thanks, Frank
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