Crack resistance check problem [resolved]

[Paul Birkeland]

Pin 3 looks to be touching pin 4.  This would short one cathode to ground and pull the plate voltage low, which is what you have.  I would trim the LED lead that's poking out of A3.  Definitely do this if you see similar leads poking out elsewhere.

[pyflaw]

Pin 3 was touching pin 4. I have trimmed the LED lead that was poking out of A3 plus others. I adjusted all the wires that are closed to each other especially 2 wires which have the conductor of one wire touching the plastic shield of another wire.

I remeasured all the voltages. Now they are within 10 to 15% of the expected values.

I have connected a set of headphones to the amplifier and the loud hum on the left channel is gone. I will monitor it for the next few days. If it runs stable, I will move on to the Speedball upgrade.

Thanks all and especially Paul for all your helps.

[Mucker]

Always fun to read these problems getting resolved. Nice job all around.