Crack resistance check problem [resolved]

pyflaw · 1680

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Offline Paul Birkeland

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Reply #15 on: September 16, 2023, 06:29:06 PM
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.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline pyflaw

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Reply #16 on: September 18, 2023, 10:24:34 AM
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.



Offline Mucker

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Reply #17 on: September 18, 2023, 12:36:31 PM
Always fun to read these problems getting resolved. Nice job all around.