TSL100H Is some hum normal?

[siod]

Hello.
I just got a "new to me" TSL100H and when I switch on the power everything is fine.
Once I flip ON the standby switch, I hear it hum even when all the dials are set to zero.
When I plug in a guitar cable to the input, it hums a little louder.
But not to the point where I can not hear the relay click when I switch channels...

My DSL401 does not do this at all, so I am assuming this is not normal.

I swapped out the pre amp tubes but the problem was still there.
I set the bias to 90mv on both sides but the problem was still there.
I changed outlets, no floresent lights or power cables near me...
I measured the frequency of the hum and it seems to be close to 60 cycles.
I have made a quick 30 second video but alas I cannot upload a video here....

Anyone have any ideas?

 

[Dogs of Doom]

this is the 2nd thread on this amp...

make sure you keep all the questions in 1 thread please.

Check the bias. An out of balance bias will cause a balance hum. This could mean that you need new power tubes.

But, these amp's are notorious for other issues, so it could be a number of things. Try the bias & power tubes thing 1st...

 

[siod]

Sorry, I am new here...
I balanced the bias and visually inspected the power tubes and tested each and every pin for shorts...
Still hums...

 

[Dogs of Doom]

could be a cap going south...

I'm not real tech oriented, so, hopefully someone w/ more experience will be in here before too long. I do have some experience w/ my TSL though...

are you capable of working inside a tube amp w/ lethal voltages?

 

[siod]

Yes, I can remove and replace components and run tests with my good old multimeter, but I do not have access to an oscilloscope at this time...

 

[Dogs of Doom]

1st thing I'd say is pull the chassis & give it a good visual inspection under good light. Look for the obvious, like any charred components, soot, bulging cap's, etc.