If the multimeter probe causes the same problems, connect the scope across the gate and source to see what changes when you touch the drain.
The first, low amplitude waveform may have been noise. It wasn't a good drive. Touching the drain may simply have triggered the rail-rail oscillation which caused the increase in current.
You can also try simply driving a signal into the amp to see if that makes the same changes as touching the drain.
The first, low amplitude waveform may have been noise. It wasn't a good drive. Touching the drain may simply have triggered the rail-rail oscillation which caused the increase in current.
You can also try simply driving a signal into the amp to see if that makes the same changes as touching the drain.
yeah, driving a signal into it from my phone does trigger it.
Oh, CCS pot was still slightly increased, brought it back to stock values and now the bad drive is gone. Current draw about 1.47A
testing the low side (both sides still on the single previous 31n20d fet)
low side gate to source:
the high side:
There are some differences from the high side, could that be why the high side is heating up and not the low side?
I could try putting in a few more of the 31N20Ds to see how it changes if needed
Oh, CCS pot was still slightly increased, brought it back to stock values and now the bad drive is gone. Current draw about 1.47A
testing the low side (both sides still on the single previous 31n20d fet)
low side gate to source:
the high side:
There are some differences from the high side, could that be why the high side is heating up and not the low side?
I could try putting in a few more of the 31N20Ds to see how it changes if needed
I only have 3 per side, thought I had a few more but this will have to do.
Heating is slower compared to 1 per side, I think a smidge faster than the full 5 per side of 38n20ds
1.52A current draw.
high side:
low side:
Heating is slower compared to 1 per side, I think a smidge faster than the full 5 per side of 38n20ds
1.52A current draw.
high side:
low side:
At this point, I think I'd run the 3120s up to moderate power and note the heating rate (clamped to the heatsink). Then do the same with the replacements to see how they compare in their rate of heating.