SVT-CL Output Tube Schematic and Layout Needed

[TimmyP1955]

Does anyone have an SVT-CL Output Tube Schematic and Layout? I have several sets of SVT-CL documents, including some from Ampeg (I think), but non have these documents. Without the missing documents, I cannot sort out which pins of J11 connect to which 6550 (without pulling the tube board out and checking for continuity). Not that I expect knowing to tell me anything ;-(

I'm trying to solve the usual red light-no green light issue on one triplet. The amp powers up and puts out full power, but I want it right. I swapped tubes between sides to no avail, checked all the components on the output board, and made sure that the LED is good.

I measured all of the voltages on ICs 3-6 and nothing looks amiss. All of the tube sense pins have between 162mV and 290mV. The voltages on the pins that feed the green LEDs match (within 200mV).

[The Dude]

Ampeg_SVT-CL.pdf

This is what I have. No layout, but you should be able to trace it out.

[nevetslab]

Ampeg SVT-CL Output Tube PCB photos/Technical Note, schematic, parts placement dwg

While Ampeg never published a top/bottom PCB layout drawing like they had done on other boards, I do have this one Technical note that shows the PCB fairly clearly on the top side, though not all of the bottom side. I do service these regularly, and will add that to my agenda to get assembly photos for my database and post it.

Technical Information Bulletin (TIB0003, June 2001) -- Power tube PCB modifications.pdf
Tube PCB Schematics (41941h3_).pdf
Tube PCB Pictorial and Parts List (41941p5_).pdf

[TimmyP1955]

Thank you sir!