Stereomour II - Right Channel Issue Troubleshooting

[Paul Birkeland]

Does this voltage follow one of the 2A3s if you swap it?

It also jumped out at me that some of the STP heater wiring feeding the 9 pin sockets is up above the rest of the wiring, and one of the bare shield wires looks perilously close to shorting out one of the plate connections.  This wiring should be installed against the chassis for quietest operation, but I wouldn't address this until the other issue is resolved.

[vtecths]

Appreciate the callout on the heater wiring. I made sure none of them are shorted but will address after this issue is resolved.

Swapping the 2A3s net the following updated measurements:

#1: 368.5V [from 370.3V]
#2: 397.2V [from 403.5V]
#7: 210.2V [from 173.3V]
#14: 208.0V [from 207.5V]

The distorted output doesn't appear to be following the tube.

[Paul Birkeland]

You've posted all the voltages that were OK to begin with, what we'd be most interested in is seeing if the 85V readings switched sides.

Oddly the problematic 2A3 voltages on the left channel...

Can you measure the DC resistance at terminal 36?  It looks like one of your 5W resistors is missing the lettering, and really your amp is acting like only one of those resistors is present.

[vtecths]

I ended up replacing that 5W resistor. This resolved the static/distortion in the left channel, however I'm still experiencing the right channel tube running noticeably warmer [~100 degrees F].

I ran through another round of resistance measurements after swapping the resistor. I'll attach these.

Terminal 36 and a few others still don't measure quite right.

[Paul Birkeland]

2.9K on terminal 15 means that only the 3K/5W resistor is appearing there, and the 2K/5W resistor just isn't connected or well enough soldered to be doing anything.  This is what you'll need to address to even everything up.