Elevated filament supply

[bosch]

I've changed things around a bit on the 4 lug tag strip (all lugs are connected to each other):

Lug 1 (top in the picture): 6.3V VCT
Lug 2 (attaches to chassis): 10uF Cap ground & PT CT
Lug 3: 100uf+100uF Cap ground & signal grounds
Lug 4: Speaker terminals common

Also;

I Cut the ground bus to separate the ECC85 from the KT88s and the 33uF Caps.
Connected ground from the ECC85 to the ground bus near the 4 lug tag strip (other side of the KT88s and 33uF Caps).


There's still a hum but I'm sure it's reduced.....

 

[Le Basseur]

1.I cannot see in your pictures...how are positioned XFMR,choke and OPTs?
2.Try moving the grounded input (marked with the red arrow) somewhere else

 

[Depanatoru]

First of all I would take the power transformer away from chassis and see if something is changing . It could be easily magnetic field from transformer going into chassis ...

 

[bosch]

1.I cannot see in your pictures...how are positioned XFMR,choke and OPTs?
2.Try moving the grounded input (marked with the red arrow) somewhere else

I'll post a picture of the top so you can see the layout.


The wire you've marked is just connecting the metal plate that the RCA inputs and speaker Jack's are mounted on to the top plate so that it's Connected to earth. The input is grounded at the volume pot.

 

[bosch]

First of all I would take the power transformer away from chassis and see if something is changing . It could be easily magnetic field from transformer going into chassis ...

This is what I was wondering about. I'll have to find some time to pull the power section apart and try running the amp with the PT separated from the chassis....