I new to building chip amps and electronic in general, so be gentle...
I completed my BrianGT LM3875 kit today, my first one. I followed the instructions to the letter, double-checking everything along the way.
I mounted eveything onto a slab of masonite, on standoffs, of course. As I didn't know how I wanted to configure the final power supply I was going to use, a bought a transformer for $10 from Radio Shack to make sure everything worked.
It's marked 12.6-0-12.6V, 2A on the secondaries and 120V 60HZ on the primaries, which seems ok based on what I read. There are three wires coming out of the secondary side - yellow-black-yellow. I hooked one yellow to each the AC1 holes on the board, the black wire to the PG+.
I should mention, I 'm using the "legacy" configuration, with the 8 diodes and two small capacitors.
When I hooked the power supply board to the transformer and switched it on, a little smoke came from D2 and D6, and by the time I switched it off, they'd getten so hot they'd melted their solder and were loose in the socket (everything tightened up as it cooled).
I'm not inclined to plug the thing back into the wall until I have some idea what I did wrong. Any ideas?
I completed my BrianGT LM3875 kit today, my first one. I followed the instructions to the letter, double-checking everything along the way.
I mounted eveything onto a slab of masonite, on standoffs, of course. As I didn't know how I wanted to configure the final power supply I was going to use, a bought a transformer for $10 from Radio Shack to make sure everything worked.
It's marked 12.6-0-12.6V, 2A on the secondaries and 120V 60HZ on the primaries, which seems ok based on what I read. There are three wires coming out of the secondary side - yellow-black-yellow. I hooked one yellow to each the AC1 holes on the board, the black wire to the PG+.
I should mention, I 'm using the "legacy" configuration, with the 8 diodes and two small capacitors.
When I hooked the power supply board to the transformer and switched it on, a little smoke came from D2 and D6, and by the time I switched it off, they'd getten so hot they'd melted their solder and were loose in the socket (everything tightened up as it cooled).
I'm not inclined to plug the thing back into the wall until I have some idea what I did wrong. Any ideas?
gcnewbie said:
In the original BrianGT clone thread (and i expect the manual), it shows how to hook up the boards with a centre tapped trafo... with this kind of device you only use 4 diodes i believe.
If this trafo is anything like the 12.6V centreTapped ones you can go in and separate the windings -- we do this to get 2 6.3 V windings for filaments. If this is possible then you would have a dual secondary trafo and could hook it up with 8 diodes (after you replace the frided ones)
dave
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