Supro Royal Reverb repair

[Steelwitch]

Hey pals,

I’m finishing up a repair a previous tech has started but never finished. He recapped all of the filter caps in the amp and did a decent job. Part of the complaint that the customer has is that when the reverb it turned up it attenuates the signal significantly. Has anyone had this issue? The reverb tank is pretty small and probably not in great shape but would love to figure out if there’s a way to improve the mixing between the dry and wet signals. There’s no DC voltages on the schematic, just wondering what kind of voltages I can expect from the power supply. Overall, I don’t think this amp sounds particularly good, but it’s not due to noise or anything— maybe it’s not a great sounding amp to begin with. I figured the power supply should tell me what’s going on and why. Here’s a link to the schematic! http://www.oldfrets.com/Valco/Schematics/Supro_6650.pdf

Something I still need to do is replace the 1k 7w resistors that drop the B+, they look pretty crispy. I can only find 5w though! Anyone know a good source for ceramic 7w?

[Jazz P Bass]

Man, what a convoluted circuit.
Tone control meets the reverb return.

Raising the reverb control full on should be a higher resistance to ground signal wise than when it is turned down.
(10K + 50K)

I would try disconnecting the reverb return wire from the pan (they are oriented correctly, right?)
If the volume drop at full reverb on diminishes, then the reverb return coil is what may be lowering the volume.

I have included the Fender DR schematic as a circuit reference.

65_Deluxe_Reverb_RI schematic.pdf

And a copy of the 6650 as I cannot rotate the one that you linked.
Supro_6650.pdf