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+--- Thread: Missing segments on all digits (HP-55) (/thread-11124.html)
Missing segments on all digits (HP-55) - bakerjp - 07-25-2018 09:52 PM
Missing b, c and d for all digits.
Simple fix? Ideas?
RE: Missing segments on all digits (HP-55) - teenix - 07-26-2018 09:23 PM
(07-25-2018 09:52 PM)bakerjp Wrote: Missing b, c and d for all digits.
Simple fix? Ideas?
Could be a faulty anode driver chip or may be corroded/broken connections between the LED display and this chip.
I'd check the keypad/display PCB first.
cheers
Tony
RE: Missing segments on all digits (HP-55) - Harald - 07-29-2018 09:52 PM
Or possibly a bad solderjoint on an inductor array or driver chip.
RE: Missing segments on all digits (HP-55) - bakerjp - 07-30-2018 05:25 PM
I thought that since the error was so "definite" somebody
(who understands the drive logic more than I do) could
determine the exact cause. Missing the same segments on
all digits to me indicates a single problem. But I might be
wrong about that. And the problem may be beyond repair.
I've read articles about this from Alex Knight, Joe Rigdon
and Tony Duall but my tools are basic; I'm an engineer
but not an electrical engineer. I do miss my calculator, though.
I've been using it for more that 30 years.