NAD: 1968 Fender Pro Reverb

[rullywowr]

I've gotten hit with a cap on a fender deluxe and it's no fun. Just look, and take pictures.  Don't touch anything inside unless you are familiar with how to drain the caps safely. There's lots of good articles regarding that on the web.

[lincolnic]

I finally had a chance to get under the hood today, and unfortunately it looks like it's not the AA165 circuit after all. It's the AB668 - the first silverface circuit. I think I'd like to try blackfacing it sometime, but I've never done any amp work before. Have any of you blackfaced a Fender before? Any thoughts?

I did take a lot of pictures for those of you who want more amp porn, but I haven't transferred them to the computer yet.

[alexradium]

The most difficult thing to do is the bias arrangement,circuit wise.
Search for any site that gives info on how to do the whole thing and realize if you could accomplish all of it.
I guess Paul Marossy had a section about it on his diyguitarist site.

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[alanp]

I tend to always refer back to the MetroAmp build guild for 50W plexi's for biasing any amp -- it has a really good page on it that explains the voltages, watts, and maths involved.

Googling the AB668, the first schematic I came across shows a cathode bias arrangement of some kind, no adjustment needed as long as you have 6L6's in it? Should be a couple of chunky 7 watt resistors going to ground from the power valve sockets.

[alexradium]

The mixed cathode/fixed bias is the reason why this amp doesn't sound so good as it should.

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