Tube amp with a part/component I'm unsure of...

[kevtronic]

I'm working on a 60's 440s Guyatone (tokyo sound) amp that has a part I haven't seen before. The schematic shows a diode and capacitor in parallel, but the amp has this black plastic looking part with a single red dot on one end. It tests like a diode. I can't really get a reliable reading on it with my capacitance meter. Does anyone happen to know what this is? I've attached a picture that shows the parts



Thanks...

[52 Bill]

...but the amp has this black plastic looking part with a single red dot on one end. It tests like a diode.

They are just silicon diodes SH-1 or something like that. If there are caps, they usually are ceramics added to snub the noise from the diodes.

[Justin Thomas]

Yup, see them in mid-late-60s Ampegs all the time - the ones with full-wave bridge rectifiers, though without the caps.

Justin

Just noticed the dowel jammed under the board... nice!

[Jazz P Bass]

SH-1 Diode for sure.

SH- 1, Tube SH-1; Röhre SH- 1 ID58393, Solid-State-Diode

[kevtronic]

Ya - I'm using the dowels to hold the board up off the chassis while going thru the amp. I figured they were just diodes, but better to ask and look dumb than not to ask and be dumb as I've never seen them before. Thanks for the info...

[kevtronic]

Thanks for the info. I couldn't seem to find any info on them searching the web based on the schematic or info on the diodes...

[kevtronic]

SH-1 Diode for sure.

SH- 1, Tube SH-1; Röhre SH- 1 ID58393, Solid-State-Diode

That would be them. Thanks for the link...

[Enzo]

And think about it, a diode with a parallel cap would test like a diode, wouldn't it? And a cap with a diode across it probably wouldn;t test well as a cap. Though the signal from the cap test is likely DC current, so reversing your leads during the cap measurement MIGHT make a difference.