[sceleratus]

   
There's hum in the headphones even with all the valves unplugged? That makes no sense at all.
 
~Tom

Very light. A background hum.  Faint, certainly compared to with them in.

 

[tomchr]

  What about TU1 and TU3, pull those as well?

 No. The whole point is to let the small-signal tube amplify whatever hum may be on its input so you can measure it. 
 
~Tom

 

[sceleratus]

WIth the OPT shunts in,
With the DMM in Max/Min/Ave mode probes to left and right chan P2 will start at 60mV and drop quickly to 20mV continuing to  drop from 15mV but slowly.  Pulling the probe resets the sequence.   I [size=medium]presume this is a cap activity.[/size]

 

[sceleratus]

   No. The whole point is to let the small-signal tube amplify whatever hum may be on its input so you can measure it. 
 
~Tom

ok

 

[sceleratus]

WIth TU1 and TU3 in the Grid voltage on TU2 and TU4 rose from -232V (spec) to -76V
 
EDIT:
 
Reading the startup procedure this is the correct voltage for TU2/TU4 Grids when TU1 / TU3 is insertyed.
 
There is still a faint hum.

 

[sceleratus]

 
 
With valves TU1 and TU3 in, I clipped to the J8 ground on the Driver Board and probed Pin 2 of the output jacks.
The image of the higher amplitude wave is the Right Channel.  Multiple exposures were taken to catch the wave phase shift.   If these are of any use at all...
 
 

 

 
 
​
 

 

[tomchr]

Suggestion: Use the line trigger on the o'scope. If the hum really is 60 Hz (or harmonics), the scope should show a clear image.
 
~Tom

 

[sceleratus]

I ride the short bus.  My o'scope has these triggers:
 
Edge, Pulse Width, Video, Slope, Alternate, Pattern and Duration Trigger 
 
 
I'll see what I can find on YouTube

 

[sceleratus]

Probably a good idea....
I get the exact same wave form when the amp is OFF

 

[nikongod]

  Very light. A background hum.  Faint, certainly compared to with them in.

 
Magnetic coupling. 

 

[sceleratus]

Couldn't get a grasp on triggers after several YouTube tutorials....
Magnetic coupling must be really strong since I moved the OPT's an additional 1" to 1.5" further from the face of the power trans.
Hard to imagine this popped up now after testing in death trap mode and running production for over a month.   I also looked at transformer positioning of the Electra-Fidelity Silver 45.  Eyeballing it my distances are equivalent to greater.

 
 


 
 
 
 
Reached Max-Q of my abilities.  I'm in "box up" mode now.

 

[holland]

   
Magnetic coupling. 

 
It might be, or it might be environmental though I think flourescent lights should show up as 120Hz.
 
Suggestion, move to a different room.  Also, add extra wire (2 feet) to the output transformers and move that away in an aggressive manner.  Move the output XLR jacks with the transformer.  Solder the wires, and scotch electrical tape (rated to 600V) to wrap.  I'm not sure about generics.
 

  Suggestion: Use the line trigger on the o'scope. If the hum really is 60 Hz (or harmonics), the scope should show a clear image.
 
~Tom

 
I would like to see a single cycle as well, but this is probably good enough.
 

  I ride the short bus.  My o'scope has these triggers:
 
Edge, Pulse Width, Video, Slope, Alternate, Pattern and Duration Trigger 
 
 
I'll see what I can find on YouTube

 
Just hit all of them, to experiment.  Start with Duration, trigger on high (not sure if there is a voltage level to set, but if so, set to something like 1mV), and capture about 60ms of data.
 
The noise pictures you are posting is the same as what was on the output.  Was this with the input connected to the input XLR?  Can you disconnect it and ground the inputs to the driver board?
 
Also, can you probe the input XLR jack?  I think you may have done this already, I forget.

 

[sceleratus]

 
Just hit all of them, to experiment.  Start with Duration, trigger on high (not sure if there is a voltage level to set, but if so, set to something like 1mV), and capture about 60ms of data.
 
The noise pictures you are posting is the same as what was on the output.  Was this with the input connected to the input XLR?  Can you disconnect it and ground the inputs to the driver board?
 
Also, can you probe the input XLR jack?  I think you may have done this already, I forget.

Tried many different scope trigger configuration.  I didn't know what I was looking at.
 
I probed the driver board with all the inputs removed.
 
Doesn't matter now.  It's in a box
 
Thanks to everyone for the suggestions and encouragement.  Wish I could have figured it out on my own.

 

[tomchr]

Damn... I'm curious to hear what Jack finds out.
 
~Tom

 

[sceleratus]

  Damn... I'm curious to hear what Jack finds out.
 
~Tom

 
you have no idea........ actually you do.