I managed to get everything hooked up with 44V across +/- and the offset zeroed by changing R7 to 49.9k. But it won't play any magical sounds out of either side.
These are Buzz's old M2 PCB's.
What points should I measure to see where the problem is?
Check polarity (-) (+ ) of 10 uF little electrochemicals all is ok ?
Best regards
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Hey Zen Mod, I'm using Toshiba 2SK1530/2SJ201 as well. Is this bias tweak to get the Toshiba's to a more optimal operating point and to coax a bit more current drive, since these are lower transconductance parts than Fairchild and IRF parts?
Thinking about putting 1R3 parallel with 0R47 and 10R parallel with 221R so as to compare the two Iq's.....hmm
Cinco
I managed to get everything hooked up with 44V across +/- and the offset zeroed by changing R7 to 49.9k. But it won't play any magical sounds out of either side.
These are Buzz's old M2 PCB's.
What points should I measure to see where the problem is?
I would PM buzz....I suppose your heatsinks are warming up and you are getting proper measurement across source resistors? Or no?
Russellc
I managed to get everything hooked up with 44V across +/- and the offset zeroed by changing R7 to 49.9k. But it won't play any magical sounds out of either side.
These are Buzz's old M2 PCB's.
What points should I measure to see where the problem is?
When Justin put his boards up for sale he mentioned an error which requires wrapping the source resistor around the soldered leg of the MOSFET. Did you do that?
http://www.diyaudio.com/forums/swap-meet/282086-pass-m2-clone.html#post4507731
Source resistors are warmed up and sitting at 0.63vdc
C2 measures 333. mvdc
Both C2 capacitors are connected so + is to transformer, same as in schematic.
22V + and - testing to board ground.
C3 is 10V
Grinberg,
Yes I did fangdangle the one board to match the schematic. basically swap the grid and source on the one IRFP FET
C2 measures 333. mvdc
Both C2 capacitors are connected so + is to transformer, same as in schematic.
22V + and - testing to board ground.
C3 is 10V
Grinberg,
Yes I did fangdangle the one board to match the schematic. basically swap the grid and source on the one IRFP FET
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Looks like both transformers are broken
pin1 to ground = no connection. It should be 230r or so.
Thanks for everyones help.
The transformer's wiring on Buzzforb's PCBs does not match the published schematic. He swapped pins 1 and 3, 7 and 5.
If you are wondering how do I know that, the answer is: I have an unused pair of his boards.
Attachments
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....after soldering little hair strand on the output winding of transformers magical sound is now playing.
Congratulations Damuffin
