OK-- here's an update. I was so emotionally damaged from the piece of wire that wound up in the tranny that I put the project down for a while, then got snowed under with work.
I did take the bell ends off, but I never found the bit of wire. Unless it's seriously jammed in there, I think it must have bounced back out when I was fiddling with it.
Anyway, the tranny is back together and I mounted the rest of the components. Thanks to the reminder post from bigjppop, I'll resume the project today.
Pictures to follow.
Kofi
I did take the bell ends off, but I never found the bit of wire. Unless it's seriously jammed in there, I think it must have bounced back out when I was fiddling with it.
Anyway, the tranny is back together and I mounted the rest of the components. Thanks to the reminder post from bigjppop, I'll resume the project today.
Pictures to follow.
Kofi
I've always liked the JJ tubes, but I'm not really an expert. I've never had one fail and I think they sound great. Price is right as well...
So, I hooked up the amp last weekend and I was popping fuses all over the place. I noticed that I had some reverse continuity in one of the PSU diodes, so I rebuilt the supply with new diodes. Upon starting up this morning, I saw the B+ rise to about 390VDC and then the 1A fuse popped. I tried a 2A just to see if the inrush was killing it, but it popped right away without the B+ rise the second time.
I think I'll disconnect the supply and test it standalone. Any ideas on a resistor value that would be good for testing the supply? Any ideas on what may be causing this?
Kofi
So, I hooked up the amp last weekend and I was popping fuses all over the place. I noticed that I had some reverse continuity in one of the PSU diodes, so I rebuilt the supply with new diodes. Upon starting up this morning, I saw the B+ rise to about 390VDC and then the 1A fuse popped. I tried a 2A just to see if the inrush was killing it, but it popped right away without the B+ rise the second time.
I think I'll disconnect the supply and test it standalone. Any ideas on a resistor value that would be good for testing the supply? Any ideas on what may be causing this?
Kofi
Koffi, here's a direction you can try if you feel inclined - maybe double check your power supply caps are wired for correct polarity, then double check your bleeder resistor/s for correct value. Then disconnect the OPT from the B+. Measure the DC resistance (with power off of course) between the feed to the OPT and ground. This will check all of the amp except for the diodes/main filter caps/choke. You should measure megohms. If you measure less than megohms, there is probably a wiring error in the amp itself, not the power supply.
Edit - another thing to check is that the heater wires aren't accidentally short circuit.
Edit - another thing to check is that the heater wires aren't accidentally short circuit.
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Thanks for the advice!
I didn't find a short on the filament wiring, so I disconnected the OPTs from the B+ and found that when I connected the VOM between the paralleled filter caps and the positive lead of the OPT secondaries, the right one showed about 18M ohms and the left one showed zero. I'm guessing that means that I have a short on the right side wiring somewhere, right?
I didn't find a short on the filament wiring, so I disconnected the OPTs from the B+ and found that when I connected the VOM between the paralleled filter caps and the positive lead of the OPT secondaries, the right one showed about 18M ohms and the left one showed zero. I'm guessing that means that I have a short on the right side wiring somewhere, right?
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