• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Strange Grounding Problem - My best guess: ghosts.

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spice,

I take it that the heaters are on when it fails?

Regards
M. Gregg


do you meat the heating system in the house? it's winter now, so yes, and it did start acting like this when i got cold and i put my heat up, though i don't remember if that is directly connected in timing. But its working now and the heat is on, though the unit has been on for 2 days now. its an oil heater, do you think its messing with the circuit?
 
do you meat the heating system in the house? it's winter now, so yes, and it did start acting like this when i got cold and i put my heat up, though i don't remember if that is directly connected in timing. But its working now and the heat is on, though the unit has been on for 2 days now. its an oil heater, do you think its messing with the circuit?

Uh, I'm pretty sure he's asking if the tubes are lit up when the sound stops :)
 
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It has got to be component fail.

so something you can try is to measure the current in the Gnd cable to the star point from the capacitors in the PSU with a multi meter.

Also measure this when the circuit seems good so you can compare it when it fails!
Please be careful HT bites!

Just for interest have you tried it in a different mains socket! Just a thought " I am thinking Gnd fault!

Regards
M. Gregg
 
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It has got to be component fail.

so something you can try is to measure the current in the Gnd cable to the star point from the capacitors in the PSU with a multi meter.

Also measure this when the circuit seems good so you can compare it when it fails!
Please be careful HT bites!

Just for interest have you tried it in a different mains socket! Just a thought!

Regards
M. Gregg

Ok tonight i'll measure gnd cable current between psu caps n star ground

I have it in a power conditioner where i have 8 or so other things plugged in, i have tried different sockets that i know work, but ill try using different wall sockets next time it fails.

whats most likely to fail? probably the chip right? hey uhhh yeah as i wrote that i put my hand on the chip in the psu with the enormous heat sink on it and its hardly even warm -_- it might be above room temperature only because 2 ele caps right near it are putting off heat. I don't remember that being the case when i built it... I mean why would there be a heatsink 100x bigger than the chip if it only got moderately warm? that seems like the likely cuplrit, no?
 
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The unit finally started acting up again and there is a corresponding voltage problem from the PSU

Input 220 vac

output 226 on the - rail
output 23 on the + rail

The + rail during normal operation produces 222

There is the problem!

When taking the PCB out to take more measurements it started working again, so i couldn't narrow it down.

I'm guessing I can track the 'bad' AC voltage back into the power supply, see where it changes (at what component), then replace that bad component?
 
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