well, the zener did the trick. i replaced it ,and all is fine.
once i got it working, the offset was still around 2.8V. Magura suggested to just wire it all up, instead of having the alligator clips. sure enough, that was the problem.
now, dc offset is 0.08VDC. that is more like it!
thanks to everyone, i will have pictures soon. it is a very nice looking amplifier. i cannot comment on the sound because i dont have a case, and im not gonna bring the thing upstairs on my maggies until it has a proper case. but on the little bookshelf mini-system speakers, it sounds good. (no popping, clean, clear sound. its working correctly). thats all those speakers can tell you
once i got it working, the offset was still around 2.8V. Magura suggested to just wire it all up, instead of having the alligator clips. sure enough, that was the problem.
now, dc offset is 0.08VDC. that is more like it!
thanks to everyone, i will have pictures soon. it is a very nice looking amplifier. i cannot comment on the sound because i dont have a case, and im not gonna bring the thing upstairs on my maggies until it has a proper case. but on the little bookshelf mini-system speakers, it sounds good. (no popping, clean, clear sound. its working correctly). thats all those speakers can tell you
well, here are the lovely pictures. not much to look at now, but hopefully once my cases come in, they will be a bit nicer. but everyone likes to see things.
here is the temporary PSU with rectifiers, caps and tranny.
this is the amp side with boards, heatsinks and meter (which is not hooked to anything right then) the grounds on the speaker terminals and input jacks are incomplete as well.
this is the enclosure for the actualy cap bank that will be used. currently they have copper bars connecting them. the heatsinks sit on the sides, and the transformer sits below the main board (separated by a large metal plate) i have ordered the cases from par-metal and they should be here in a few days.
here are the specs:
(aleph 3 of course)
transformer: 18-0-18 250VA avel lindberg (exactly 25.04V rails)
bridge rectifiers: 600V, 35A
total of 208,000uf capacitance
all vishay resistors
black gate capacitors
heatsinks get hot. they settled down around 60-65C. a bit too hot to touch, but they also had little ventilation sitting face down. they will be mounted vertically, and vented.
here is the temporary PSU with rectifiers, caps and tranny.
An externally hosted image should be here but it was not working when we last tested it.
this is the amp side with boards, heatsinks and meter (which is not hooked to anything right then) the grounds on the speaker terminals and input jacks are incomplete as well.
An externally hosted image should be here but it was not working when we last tested it.
this is the enclosure for the actualy cap bank that will be used. currently they have copper bars connecting them. the heatsinks sit on the sides, and the transformer sits below the main board (separated by a large metal plate) i have ordered the cases from par-metal and they should be here in a few days.
An externally hosted image should be here but it was not working when we last tested it.
here are the specs:
(aleph 3 of course)
transformer: 18-0-18 250VA avel lindberg (exactly 25.04V rails)
bridge rectifiers: 600V, 35A
total of 208,000uf capacitance
all vishay resistors
black gate capacitors
heatsinks get hot. they settled down around 60-65C. a bit too hot to touch, but they also had little ventilation sitting face down. they will be mounted vertically, and vented.
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