Paramour 1 - 27 mv hum problem

[Paul Joppa]

This made me look up my old manual - sure enough, there is no resistance test at the 2A3 plate. We must have thought there was no possible way the plate could be grounded. We were so innocent back then!

Anyhow, the plate IS grounded. No point in checking anything else until that's resolved. Only two components connect to the plate; that should make it easier, right?  :^)

 

[patrickamory]

This made me look up my old manual - sure enough, there is no resistance test at the 2A3 plate. We must have thought there was no possible way the plate could be grounded. We were so innocent back then!

Anyhow, the plate IS grounded. No point in checking anything else until that's resolved. Only two components connect to the plate; that should make it easier, right?  :^)

PJ you were absolutely right! For some reason I had a lead connecting T21 back to T12, thus grounding the plate. I must have mistakenly soldered that in when redoing the wiring around the cathode bypass cap which I replaced at the beginning of this project.

The diodes light up and all voltages read correctly now.

On to the hum adustment and then putting this back in the system. PB, I will probably send both amps to you for a rebuild anyway when my regular amp returns from the shop. Thank you so much for your help, gentlemen.

 

[Paul Birkeland]

We must have thought there was no possible way the plate could be grounded. We were so innocent back then!

I did see this once in a SEX kit also.  It's imperative to check the DCR of the plate choke on that channel to be sure it survived the incident.

 

[patrickamory]

I did see this once in a SEX kit also.  It's imperative to check the DCR of the plate choke on that channel to be sure it survived the incident.

Check it out of circuit right? And it should be 270 ohms?

 

[Paul Birkeland]

Yes, you should be able to measure it in circuit.  It may be off by 10% or so; that would be normal.

 

[patrickamory]

I get 260.3 ohms, in circuit.