Deluxe Reverb schematic discrepancies?

[Randall]

As I look at the Deluxe Reverb 763 layout drawing I notice it does not match the schematic in a couple of places. Specifically, the .047 cap in the tone stack on both channels is .033 on the layout. And the 3.3M ohm resistor across the 10pF cap where the reverb mixes in is 4.7M on the layout. Which is correct, and does it really matter? Thanks.

[Enzo]

Go with the schematic unless there is a reason not to. And if you see such a discrepancy and have the amp in front of you, just leave it whichever way it was, don't assume one is "wrong". Unless you have a compelling reason to change it. Changes to circuits were made all the time as production went along. A schematic drawing and a layout drawing may have been made at a different time and reflect such changes. Or it may just be a mistake, as in someone just copied a different layout thinking it was the same and not noticing the details.

Looking at the AA763, I see 0.033uf caps on both, but the AB763 schematic has the 0.047 but the layout is still that of the AA version in that regard. The later versions all have the 0.047 as well.

Look at the AA763 and AB763 schematics to see both values used. The layout will be the same, just chenge the part value, but install in same spot.

[Randall]

Thanks Enzo, it didn't even occur to me to look at another version. This is a build, so I have no amp to look at, but I do have the re-issue schematic, and it uses .047 and 3.3M as well.

[Joe L]

That is the values that John D. (my best friend) and I used when we built our two clones and it worked and sounded just dandy. In fact, they sounded so good I built a VibroVerb clone that kills.

[Randall]

Hmm... found another one. Layout calls for a 56K on the cathode of the 12AX7 trem tube on the iso-op side. Original and re-issue schematics show 100K. And I'm not done yet.

[Enzo]

Again, what has happened is they changed some things from AA763 to AB763. The changes are on the schematic but not on the layout. The value of the layout is that it tells you where things connect. The component data should be on the schematic. The thing to do is hold the AA and AB up side by side looking for differences, then find those parts on the layout. I see a change in the tail of the PI, but the two layouts agree with their schematics.