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Anyone know about ancient LED segment displays? ID help needed.

Eudimorphodon

Eudimorphodon

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Recently bought a grab bag of assorted LED displays. Most of them were HP/Agilent HP5082-7651 7-segment units which were very clearly marked and trivial to look up... but hiding in the corner of the sack were these three weirdos, which look *very* old and primitive. Only one came with the red diffuser/panel mount box, the other two were bare. The only marking on them is a hand-lettered scribble that's inside the clear plastic molded around the module; it looks like it reads "M823" (same on both uncased units).

led_display_mystery.jpg

I know it's a heck of a long shot, but do these look familiar to anyone? There's no obvious sign of a manufacturer mark.

They only have 13 pins (DIP-14 format with one pin absent in either the pin 1 or pin 8 position) so I would guess they need to be driven in a multiplexed fashion. If anyone has a pointer to a datasheet for anything even vaguely like them that'd at least be a start. I guess I could try gently probing them with low voltage through a high current limiting resistor and see if I can suss it out, but I'd kind of hate to kill them.

(Not that I really know what to use them for, but they seem too cool *not* to find an excuse to use.)
 
wrm said:
But you can also do a large amount of recce work with a magnifying glass.
Click to expand...

Thanks to the magnifying lenses over the elements you hardly need additional help, you can clearly see the little "flying wires" connecting the contact pads on the elements to the traces on the scrap of PCB they're all sitting on. Unfortunately, though, there's some kind of black goo (insulator?) over the actual pin area along the edges, so it's pretty difficult to work out the trace arrangement from there.

(Fun thing I actually just noticed squinting through the bubbles; the decimal points are separate dies from the other seven segments.)

Thank you for the datasheet, it's at least a start and there's at least a chance this one is at least laid out similarly. These have this weird 13 pin layout but it's at least possible the 12 other pins could resemble the 5082-7414's pinout.
 
As @wrm has stated, a 5V supply, 10k series current limiting resistor (or 1k if 10k doesn't give any joy) and a bit of logical work testing each pair of pins both ways around, should yield the anode and cathode pins (providing the displays don't contain any logic).

Dave
 
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