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I have an RD100-112 that has lost most of its volume and all of its clean headroom. Any thoughts on where to start? BTW, how do they get 100 watts from 2 6L6's?
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Look at the +15 and -15v supplies. Pick one of the op amps and check at its power pins. Are both present and at about the same voltage? And check each op amp at its output pins - any sitting at DC offset?
I don;t have an RD100 drawing handy, but the RD50 has two power tubes. I might have expected a 100 model to have four.Education is what you're left with after you have forgotten what you have learned. -
Like Enzo said, the 50's have a pair of power tubes, the 100's have four.
They use a very high (700+) plate voltage to get bigger power. Seems to me they rated the 50's at around 65 watts and the 100's around 130.
The power tubes are driven through the cathodes by transistors, with the grid voltage fixed by zener diodes.
If your problem turns out to be in the power amp section it could be the zeners or transistors at fault.
From what I recall, they are finicky about the transistors, we had to get them from Ernie Ball as generic ones with the right part number didn't work right (oscillation?).Originally posted by Enzo
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There's a great website that's run for Music Man owners and techs and it's the best I've seen. Lot of knowledgeable people over there.Originally posted by g-one View Post
Take a look at the leads on your driver transistors. I had one that had the same symptoms as you describe and it had a busted lead.
Topics - Music Man Amps Discussion Forum
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