Anyone know what diode this is?

[aion]

Gutshot of the Maxon OD-820:



What type of diodes are D4 and D5 in the bottom left? These are the feedback loop clipping diodes in the circuit. Their form factor looks about the same as a zener, but I've never seen diodes with a white stripe like that and there are no markings on them - at least not on the top sides, in the gut shots I've seen from two different 820s. But these are current-production pedals, so I don't think we're dealing with obscure NOS magic diodes here!

[Pyr0]

It's hard to say, but if you actually have the pedal in front of you, just measure the Vf with your DMM and find a matching one in your stock.

[timd]

Are they germanium?

[blue_tokai]

Do a meter comparison between the ones on the board and a a 1N4148 or 1N914. My guess is its one like that. Looks like clipping diodes to me <shrugs>

[aion]

Sorry, these are just gutshots I found online... don't have it in front of me In the schematic it just says "Silicon" with no indication of what type.

[midwayfair]

They're silicon -- they aren't Zener. You can see how Zeners would be marked to the right. That Zener is there to protect the charge pump from overvoltage.

I've never seen a DO-35 silicon with a white AND blue stripe, but it's not inconceivable that they're a made-in-Japan 1S1588, which is the "Tubescreamer" diode. After all, Maxon would have ... a few of those.

[blue_tokai]

Found a schematic online for an 880 and its listed as a 1S1588 or 1n4148, so either way we were right

Cheers,

Russ

[aion]

Yep, you're right. Here's a gut shot of a reissue 880:



Same diodes as the 820. Thanks for finding that!