Gates sa39b schematic request

[pucho812]

Anyone have a sa39b schematic or manual that is legible?
Got one that hit the bench which powers and passes signal but I have zero compression meter movement and it stays stuck between 5-7 on the meter.
Adjust the zero meter knob does yield meter movement but not much.
Might be simple and just a tube.
But a schematic would help.

 

[emrr]

I put a very clear schematic around here somewhere

 

[Evertide]

This One ? View attachment SA-39b with DC Fil - 4150163073_b7c2b5b94a_o.jpg

 

[pucho812]

I put a very clear schematic around here somewhere

This One ? View attachment SA-39b with DC Fil - 4150163073_b7c2b5b94a_o.jpg

Thanks guys.
So far I ran signal and tested tubes.

Found some bad/replace tubes with my tester.

 

[pucho812]

Tubes arrived.
Ok so this unit was recently recapped by someone else. I replaced the faulty tubes.
But the unit isn’t behaving as it should according to the schematic or service manual I read.
I can’t get the unit to zero on the gain reduction meter. I have fiddled with the internal adjustment knob and it won’t zero out. The meter hangs around -5 on the scale and while the knob varies it, it still hangs around -5.

This is without running audio through it.

 

[pucho812]

Well I found an issue.
My voltages are way off.
I assume the work of someone else. I say that as they did work and returned it to use then it started misbehaving.
different schematics I have seen list different voltages. While they are all close the ones here are way off. For example on the 1612 tubes I am seeing 340vdc in reference to ground at pin 3 which schematics have it listed around 150vdc.
I hate walking in after someone else has been especially when they can’t remember what they did.
@emrr any ideas here?
I get 810vac off the transformer secondaries for B+ and 400vac ish at the center tap going into the 5v4.

 

[emrr]

Go through the big SA-39 thread, there's a lot of common things touched on.

High voltage you can't adjust says the regulated section of the supply isn't working, for starters.

810 is still 30V high even accounting for 120; you have 124 coming out of the wall maybe? If not, there's low internal current draw somewhere and the output section is the most likely place, then maybe the regulated section itself. I'm not sure where you mean you see 400VAC. The CT should be at ground.

https://groupdiy.com/threads/gates-...ion-and-modification.36432/page-2#post-449045

 

[pucho812]

Go through the big SA-39 thread, there's a lot of common things touched on.

High voltage you can't adjust says the regulated section of the supply isn't working, for starters.

810 is still 30V high even accounting for 120; you have 124 coming out of the wall maybe? If not, there's low internal current draw somewhere and the output section is the most likely place, then maybe the regulated section itself. I'm not sure where you mean you see 400VAC. The CT should be at ground.

https://groupdiy.com/threads/gates-...ion-and-modification.36432/page-2#post-449045

Thanks, I’ll be reading