I just took a look at this Vibroverb layout:

A few questions:

1. What is this? It's purpose? and where I'd find this?

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2. What is the filter pack layout on this? I know this one doesn't have the cap can, but it doesn't show the layout inside the cap can. Can anyone help me out with that?
mystery part.png
i think that's the optoisolator or something, used on vibrato circuits in fenders.

[D] connects to the power supply filters. i think the filters are on the top of the amp with the transformers i think. they're called "cap pans" i believe?
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Optoisolator is just an old school LDR. Lamp instead of LED.

Cap pan also commonly referred to as the "doghouse". Not the best design, many long B+ and ground runs.
Quote by kurtlives91
Cap pan also commonly referred to as the "doghouse". Not the best design, many long B+ and ground runs.

And we all know how much I hate those. The first time I worked on an old fender I couldn't find the caps till I opened that up and it disgusted me.

With those long B+ runs you leave yourself open to picking up a lot of interference, so you will want to make sure you keep those wires as far away from the heaters as possible.

If you take a look at the schematic the optoisolator is used to isolate the oscillator for the vibrato from the rest of the amp. This makes it so that no signal flows into the oscillator from the rest of the amp, which can actually be quite a good idea in my opinion. Your going to want to make sure that you get an optoisolator that can handle high speed switching, otherwise the vibrato will become somewhat useless and may cause problems with the amp in other places.
Awesome guys thanks! The "doghouse" won't be that far though due to the chassis size (i'm mounting it inside instead of on top). I'm gonna build this inside of an old Peavey TKO 115 bass amp chassis. Just waiting on a little more money......
sorry about the double post, but totally seperate question here:

I have three transformer units; I know that the one is the tube filament transformer, the other the output transformer. But I can't tell what leads are what coming out of the transformer. It was part of a phonograph that I stripped the chassis down and i'm making a champ. Is there anyway I can measure resistance/voltage to figure it out?