Missing segments on all digits (HP-55)

[bakerjp]

Missing b, c and d for all digits.
Simple fix? Ideas?

[teenix]

(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

[Harald]

Or possibly a bad solderjoint on an inductor array or driver chip.

[bakerjp]

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.