[mainewolverine]

I'm restoring a 1976 Mercury 204 "Drugstore" tube tester. I have a schematic which may be from an earlier model and shows a diode in the circuit where I found this component If this is a diode, I've never seen one like this. Does anyone have any ideas? It tested 1.8M ohm in one direction and 900K ohm in the other direction.

Thanks for any help.

Jim
   
   
   

[morzh]

I think it could be a selenium rectifier (yes a diode of a sort).
Plus sign usually denotes the positive out, not the P junction side as in diodes (which would be the negative out).

[sam]

whats other side of disc look

[tab10672]

Since it comes apart, I believe it is a button cell battery assembly. Are there any bias voltage symbols in that part of the schematic? Some of the old bias cell symbols look like a modern diode symbol except it should have a + and - on either end.

[sam]

that's what I was thinking tab but didn`t what to be ridiculed for saying it looked like a battery in tube radio

[tab10672]

I was shocked to find one in a 37-602 philco. I didn't even know they made batteries that small in 1937 let alone use them in a tube type electronics. Although it looks different than modern button cells (acorn shaped) it is about the same diameter as a watch batt.

[mainewolverine]

I've found out that it's a copper oxide rectifier and that they rarely go bad, so I'll put it back together carefully and reinstall.

Thanks for the suggestions.

Jim

[tab10672]

Never heard of those before, learn something new every day. Since they "rarely go bad" it's strange that it would be in an easy access/replaceable assembly.

[Chuck Schwark]

The copper oxide alloy is not solderable, hence the spring/clip type connections. Be sure you put the "disc" back in the way it came out
so it matches the polarity marking. ;)

Chuck

[morzh]

The selenium elements were not solderable either, they came as bolted assembles with solder lugs,
https://en.m.wikipedia.org/wiki/Selenium_rectifier

or in flat boxes with compartmentalized inside plastic spring loaded holders, that held serialized elements.

http://www.bakersfieldads.net/Algoso-/E2...50C250.JSP
http://oldradio.onego.ru/COMPS/selen_abc.jpg