Final Voltage Check

[Doc B]

You might try measuring resistance across the LED that doesn't light up ( amp turned off and unplugged for this). Since it is a diode it will conduct in only one direction, and in that direction give a reading with the meter probes measuring from end to end (maybe about 1.5K ohms to 2K ohms if I remember correctly). Then when you swap the probes end for end it will read infinite resistance. If it reads infinite both ways it may be damaged, in which case we can send a replacement. 

 

[Paul Birkeland]

Yes, the joints on that terminal strip look mostly suspect. When touching them with meter probes causes things to change, the components are not properly soldered.

 

[Paul Birkeland]

Yes, resolder all of the connections on that terminal strip. When measuring voltages causes intermittent connection issues, there are bad joints.

 

[dumbo]

I did a resolder on A1 and rechecked the Terminals but did not get any significant changes.  The terminals which have significant readings were: 1 (143.5), 7 (148), 19 (91), 20 (-0.01).

Here are the readings from the tube pins.  Also noted that only the LED on connection A3 was lit, the LED between A8 and the center was not.

A1  74
A2  0.0
A3  1.583
A4  -0.0
A5  -0.0
A6  148*
A7  0.01
A8  0.002*
A9  -0.001

B1  150*
B2  170
B3  149.2*
B4  74.2*
B5  170.2
B6  99.3
B7  -0.001
B8  -0.001

Not sure if you have resolved this or not.  I had similar out of whack readings.  After a couple days of pulling what's left of my hair out, it turned out to be a bad 12AU7 tube.