Right channel hum and no signal

[Sp33ls]

Oh, sorry, that was with the 6080 still plugged in.
Only 12AU7:

X: 226 & 1.9
KregA: 1.1
KregB:1.44
IA: 227
OA: 226

[Paul Birkeland]

Now try the 12AU7 and 6AQ5s with no 6080.

[Sp33ls]

12AU7 and 6AQ5s with no 6080.

X: 150& 2.5 (163 & 2.5 on B side)
KregA: 7.8
KregB:1.95

High curent:
IA: 215
OA: 150

[Paul Birkeland]

Would you be able to swap the 6AQ5s from side to side to see if the low KregB voltage follows a tube? 

Seeing 7.8V at KregA makes me very, very suspicious that you have the R1 resistors swapped on the high current C4S board.

[Sp33ls]

Swapping the 6AQ5s from side to side does not change much.

One interesting thing tho, is that the reading on KregA starts at around 9.2 and then gradually decreases in voltage at a rate of about .01VDC every few seconds. That gradual shift in voltage seems to be a common behavior I'm experiencing in a few spots. I'm just not sure what would cause a shift in voltage over time like that... 

Since the left channel appeared to be working fine, would that rule out the power supply as being the culprit? Just wondering if part of the power supply is separately responsible for each channel.

[Paul Birkeland]

A loose resistor on the 6AQ5 socket could do that.

[Sp33ls]

Hmm.. none of them seem to be loose.

So, with the  6080 inserted, the two LEDs on the B side of offending high current board light up (next to the capacitor). The other two on the A side don't light up at all.

Without the 6080, the B side doesn't light up (this might be normal, though?).

[Paul Birkeland]

The LEDs lighting up or not lighting up aren't really informative in and of themselves, but your voltages are.

The difference in Kreg voltages when no 6080 is installed does suggest an issue with the build.  This could be R1 resistors that are switched accidentally, or a miswire.  I would be paying very, very close attention to the 6AQ5 sockets.

[Sp33ls]

The R1 resistors look to be fine. I'm guessing I probably would've noticed issues earlier, tho, since my kit was working fine for about a year, right?

This issue really only appeared after removing the bell end for the transformer to paint it. Not right after, tho. There was a small period of time where everything was fine. I did touch up some joints during this time tho... Mostly around the power supply.

I'm curious if you have any spots I can measure with the power supply and high current board in order to help trace down where the issue might like.  I don't see any issues with it when scanning for bad joints, and I don't recall unwiring anything.

[Paul Birkeland]

I've suggested the spots several times in this thread.  When you took the amp apart to paint the transformer, you may have jostled a connection that wasn't solid, and hence these issues cropped up.

[Sp33ls]

Okay, I greatly appreciate all of your help. I'm going to remove the high current board and maybe swap out some of the components on there just in case. And, it'll allow me to more easily take a closer look at the 6AQ5.

[Paul Birkeland]

In my experience, blindly swapping out components on a board will just create new problems that may make debugging even more difficult.

You can measure the transistors with your meter set to beep for continuity. If it beeps between two legs, then you have a shorted transistor (rare).  A shorted transistor will usually lead to much higher than anticipated voltages though.

[Sp33ls]

Makes sense  I'll go that route first, then.

I'll report back tomorrow. Thanks, PB.

[Sp33ls]

The old 431 seems to be shorted. But, the new one I replaced it with still seems to be fine. I've checked the other transistors and none of them have the continuity going off.

When I touch the continuity meter to terminals 1-6 and 9&15 on the power transformer, I'm getting a beep with about 5 Ohms on the ones in 1-6 and 0 Ohms with measuring terminals 9&15. 

I'm assuming that this is an issue? Or is that normal...?

[Paul Birkeland]

That's normal.