question on dc voltage & volume pots

[blindsirens]

I was reading my post and its striking me as strange that the DC is on the master volume pot even when the Loop switch is set to bypass supposedly changing RY2 to be closed? And also at the 20n cap. Meaning say you set the master half way and read 5vdc on the middle tab thats what you would exactly see at the 20n cap.

[stokes]

Those two caps you mention the 100n and the 20n are connected to your PI cathode that has 48v.The 100n doesnt look like it could have any affect but check that 20n on both sides there is no need to lift it.If it has dc on the side connecting to the switch,that is your culprit.Didnt see that connection to the PI before, the notation on that page of the schem says to grid V5.But I really dont see how pulling V4 is stopping the dc from showing on that pot.That 20n and the .047 from V4a look like the only possible source for the dc to reach that pot

[Enzo]

And we should never rule out conductive crap on the circuit board.

[blindsirens]

I pulled the middle tab lead on volume pot connecting to LDR and measured 80vdc in loop bypass and 30vdc in all the other loop settings. It slowly rises over time,but starts at these amounts whenever you power it on. After finally giving in to the insanity I desoldered the LEDs and undid the pot harnesses in order to get a look at underneath(even then you can't fully flip the board). I am seeing a questionable area where one of the traces leaves the LDR heading for the relay and runs right by the high voltage end eyelet of a .68 cap (I believe its .1 on the schematic posted) this connects to pin8 and a few resistors. Anyways there is a plastic spacer hole here that cuts in extremely close to the trace running from the LDR and cap eyelet. There is 1meg continuity between the two points so I don't think its too bad,but I'll try and brainstorm a way to isolate them better. There is no green just a woody surface on the board around these points.
Then again I'm not sure which leg to follow from the four coming off that vactrol and I'm reaching for straws at this point.
I wish boogie would realize people need to get under their boards no matter how well you make an amp.

[blindsirens]

I moved the leg of that cap over to the top of a 100k resistor which the trace led to (It has different resistors on the schematic). And now it reads 110vdc at the lead going to the vol pot? I screwed up though as I did two things at once. I also reconnected all the caps I had lifted so I'm not sure what caused this. Anyways that eyelet is still there getting voltage and looks like it may be burned through to the trace from LDR,but its so slight I can't tell.
These are through plated boards so I'm not 100% sure enough to take it out or hard wire the LDR to the relay.

[Ptron]

Did you say that the voltage is present even if the loop is bypassed? When bypassed, V4 and the whole loop circuit should be completely out of the picture. If pulling and replacing V4 causes the voltage to come and go even with the loop bypassed, I would think there is some sort of unwanted connection between one of cathodes of V4 (or the junction of 22k and 82k resistor on the cathode of V4b) and the trace/wire that connects LDR14, LDR15, and RY2.

[blindsirens]

I was right about that hairy area on the board. It is arcing. You guys are awesome,thanks for helping out.
Right at the edge of the hole that holds a plastic PCB lift is a woody,rough type area. The eyelets for a 100ohm resistor(two resistors on schem) and the .68cap(.1 on schem) getting 210vdc are right at the holes edge. The trace leading from the LDRs to the relay runs right to the bare edge meeting damn near at the cap and then makes its way around to RY2. It didn't arc over the top of the board leaving a burn mark it actually arc'd THROUGH the board to the trace where the green finish on the board is just ending and the hole is punched out for the spacers. I couldn't see any obvious burn marks. I took the 100ohm(purpose?) resistor straight from pin 8 of the loop tube and jumped straight over the eyelets where the cap and one end was previously and put them all together at the 100k resistor which is where those ends lead anyways. I then scratched around the caps eyelet isolating it(I hate to do it but it was still arcing with those ends out of their holes). There is no DC whatsoever now and the amp has been running okay for about a half hour.

The only other thing I notice is that if I crank it right when I take it out of stdby I can hear a little crackling for about five seconds then it goes away. So either its still trying to arc over or its a noisey tube? Maybe I should think of a more permanent fix that won't look like hell. Also,what caused this nightmare I have no idea. I'm not sure how much I learned,but I swear I will not read too much into the symptons of amps even if it does sound like the obvious. I wonder if the newer Dual rectifiers punch those holes in different areas now. Dual sided boards are so time consuming. You have no idea where anything runs or goes. Thanks for the help fellas.