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Sunn Beta Lead solid state amp, based on date codes I'd say amp is late 81, early 82.
Sounds very close to sound of a very dirty pot but its not a pot.
It's there with or without audio, and with all volume/gain/level controls at zero or turned up.
I've retentioned the output transistor sockets, removed all caked on flux, cleaned the board, hammered on it with my paint stick - no change.
Have cleaned all jacks and pots.
Doesn't seem to be temp related, can heat it up or cool it down, let it sit for a while - still there.
Filter caps are new. +-15 is reading about 12.5 each, have about 1.5v saw tooth on the 30v supply caps.
I haven't resoldered the board yet, and there is a 4558 used as part of the DC control feedback, was thinking about popping too but thought I would check here first.
I do have a schematic if anyone wants to look at that, BTW what happened to all the schematics that were on the site? Overrun with clear.gifs
Sounds very close to sound of a very dirty pot but its not a pot.
It's there with or without audio, and with all volume/gain/level controls at zero or turned up.
I've retentioned the output transistor sockets, removed all caked on flux, cleaned the board, hammered on it with my paint stick - no change.
Have cleaned all jacks and pots.
Doesn't seem to be temp related, can heat it up or cool it down, let it sit for a while - still there.
Filter caps are new. +-15 is reading about 12.5 each, have about 1.5v saw tooth on the 30v supply caps.
I haven't resoldered the board yet, and there is a 4558 used as part of the DC control feedback, was thinking about popping too but thought I would check here first.
I do have a schematic if anyone wants to look at that, BTW what happened to all the schematics that were on the site? Overrun with clear.gifs
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