HP-41C bad display - where to start from ? - Printable Version +- HP Forums (https://archived.hpcalc.org/museumforum) +-- Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum-1.html) +--- Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum-2.html) +--- Thread: HP-41C bad display - where to start from ? (/thread-211300.html) |
HP-41C bad display - where to start from ? - Alberto Fenini - 02-11-2012 ciao a tutti, Re: HP-41C bad display - where to start from ? - db (martinez, ca.) - 02-11-2012 Alberto; Re: HP-41C bad display - where to start from ? - Raymond Del Tondo - 02-11-2012 Ciao Alberto,
IMHO the "bacon strip" interconnector is the worst of the various interconnect variants used in the HP-41,
But let's get to the LCD. There's always a chance to get non-working segments,
Or does the blanknut LCD look like on the pic before any changes?
In my experience, bad interconnectors (CPU-KBD and KBD-battery) are the most common cause for display and keyboard problems. HTH
Ray
Re: HP-41C bad display - where to start from ? - Alberto Fenini - 02-12-2012 Thank you very much for your replies. Re: HP-41C bad display - where to start from ? - Randy - 02-12-2012 Display issues in fullnuts are a real pain as the only way to trouble-shoot is to swap parts. On the upside, it is good soldering practice ;-) Missing segments have nothing to do with soldering as they are always a bad driver or a bad lcd and in some rare cases, both. If there was no corrosion in the unit, I would first try the driver. If there was any corrosion, or gold interconnects, suspect the LCD first. Based on the greenish color of the polarizer in your problem unit, I suspect it has the more problematic connector. Pink or white LCD elastomers are far more reliable than the gold. This is the opposite of the situation with the keyboard to logic board connector. Illuminating all segments: only possible with an HP service rom or PPC rom.
IMO, I would not mess with the damaged plastic lens. They are very, very difficult to replace/repair. Almost always turn out worse than they start.
Re: HP-41C bad display - where to start from ? - Alberto Fenini - 02-12-2012 ciao Randy, Re: HP-41C bad display - where to start from ? - Alberto Fenini - 02-12-2012 And, if I well understand, that the ony way to isolate the probelm, not having a PPC module, is to use a fully working unit and begin to swap elements. Re: HP-41C bad display - where to start from ? - Randy - 02-12-2012 The pink elastromeric keyboard to logic board connectors are the source of many forms of 41 trouble. They can be the source of the missing display segments although the problem is more likely to be the driver or lcd.
Troubleshoot using only the gold version keyboard to logic board connector. Change only one part per test. You changed at least three by substituting the blanknut.
Re: HP-41C bad display - where to start from ? - aurelio - 02-12-2012 Ciao Alberto, reading your words "use a fully working unit and begin to swap elements" I'm quite scared, maybe 'cause I'm not experienced like you in soldering, or maybe because always, first at school, then at work the advice for all was: "if the system works, don't touch it, let it work and it 'll work lifetime". Even if I had a dozen of 41 working HPs, never I should try the thrill...
Edited: 12 Feb 2012, 2:24 p.m.
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