AA165 drawing question

[Murrayatuptown]

Hi:

It's Molasses Mods week for me...make little progress, and very slowly when I do.

Also planning some work on a different friend's AA165-marked Pro Reverb. Not surprisingly, there are discrepancies right off the bat. It has an AA165 schematic inside, but is a silverface...so there may be mismatches vs. the drawing.

I am making a parts list so I can shop/scrounge through what carbon composition resistor values I have...he complains of cracking noises, but it's been idle for many years. New filter caps planned. Might have 2-wire AC cord...deal with that if so.

I also told him to keep it at home until I have room for it and that way neither of us has to lift it until we're ready.

So, I am doing armchair work, studying the schematic, my evolving parts list, and the layout illustration.

I have some questions about the drawing 'markers' A, E, X, Y and Z.

X, Y, and Z appear on the layout drawing but I do not see those on the schematic (or wasn't patient enough). Any idea what they relate to?

A & E I did find on the schematic. I was expecting to see them appear elsewhere, like B, C and D do in the B+ RC filtering/voltage dropping area, but they appear to only be indications for two cathode resistors shared by two 7025 sections in two separate 7025's. They are probably in the same tubes and will be obvious, but the orderly layout of the schematic separates the A and E connections. I almost didn't find one of them following the reverb tank output connection, but did. Is that all the A & E notation means, or did I miss something?

Oh, last question, probably a dumb one. I don't know a lot about reverb or vibrato switching or what the details are of the tank wiring (the amp is 25 miles away!), but the foot pedals appear to short the center conductor to the shield on the respective cables. If I already had familiarity with those circuits, what is being switched might be obvious, but they aren't yet (to me). Those work, but the cabling looks kind of ratty. Understanding will improve when I actually can compare the hardware to the drawing.

Actually, fixing any rattiness has nothing to do with the circuitry if they actually have 1/4" TR plugs, but again, I'm full of questions.

Thanks

Murray

[sluckey]

I have some questions about the drawing 'markers' A, E, X, Y and Z.

You will notice there are two points called A in the schematic. These two points are connected together. Same applies to points B.

There are also two points on the board layout for X, Y, and Z. There is a jumper wire between each pair. No need to clutter up the schematic with these.

The footswitch cable connects to the amp via two RCA Phono jacks.

[Murrayatuptown]

Thank you, Steve.

The question about what the two effect foot pedals do was more about what electrical function do the switch closures actually do.

For the vibrato it looks like the switch changes the circuit by making a connection between two lines or shorting across a component (as opposed to a completely open circuit closed by the switch contacts). I just don't have any familiarity with the circuit...I assume no LFO vs. yes LFO.

For the Reverb, I can't make out what the switch is connected to, but assume maybe it bypassed the tank (not entirely sure that would make sense because the 12AT7 driving the 25k transformer shouldn't go directly to the post reverb 7025. I don't know what the construction of the tank is for a foot switch to simply bypass).

Thanks

Murray

[martin manning]

For the vibrato it looks like the switch changes the circuit by making a connection between two lines or shorting across a component (as opposed to a completely open circuit closed by the switch contacts). I just don't have any familiarity with the circuit...I assume no LFO vs. yes LFO.

The switch lifts the ground on two of the phase-shift RC's, disabling the LFO.

For the Reverb, I can't make out what the switch is connected to, but assume maybe it bypassed the tank (not entirely sure that would make sense because the 12AT7 driving the 25k transformer shouldn't go directly to the post reverb 7025. I don't know what the construction of the tank is for a foot switch to simply bypass).

It's not very clearly drawn, but the idea is the switch shorts the center conductor to the shield, grounding out the reverb tank's output.

[Murrayatuptown]

Thank you!