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This was the very first Bass Amp SWR ever Made and they don't have a schemo for it showing the power supply.
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KB -
Geez i wish I could help you on this one, bud. We went back and forth on it a while ago. ANy reason it needs to be substantially diffferent from the standard power supply circuit of early SWRs? They used the same one over most models for quite a while, differences being only voltages and values.Education is what you're left with after you have forgotten what you have learned. -
What happened is someone changed the 2 dropping resistors after the power supply and they are getting very hot and have the burning smell from overheating. The PB-200 is the first amp SWR made then it went to the upgrades and on to the Studio 220 and I have the 220 schemos but they didn't put the resistors in the schemo just the To power amp arrows. I just noticed on this schemo and the one SWR sent me this morning that for the Studio 220 it is showing 680 and that's what is in it so maybe they are right. FWIW what you had originally sent me got trashed when my hardrive smoked and didn't want to keep harping on you for the same thing. I think the 680 ohmers are what was in the original PB-200 before it went to the Studio 220 but maybe that's why they upgraded it because these things are really to hot for comfort. Do you think I should increase them a tad ? BTW this amp is for my good bud at Komet and I really need to fix it.
KBComment
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Come on, KB, we're friends. if you are missing something I have, let me know. You are not on a limit up here at my end, you know.Education is what you're left with after you have forgotten what you have learned.Comment
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That's good to know Enzo and certainly appreciate it as always.
KBComment
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forgive me for resurrecting this old thread ... I'm in need of these schematics (and all of the previous links appear to be broken). I have the same issue with theses 680 ohm resistors getting REALLY hot, I'm guessing that an opamp has gone awry and drawing to much current.Comment
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The link thumbnail in my powst #2 still works for me. The 15v supplies are zener regulated, so those dropping resistors normally get hot. Measure and see. If your 15v rails have collapsed, then find out why. A shorted op amp would be HOT. It is much more likely a zener has shorted than an op amp though.Education is what you're left with after you have forgotten what you have learned.Comment
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Awesome ... Thanks Enzo
15v at all of the appropriate op amp pins, the heat at the blocking resistors is as designed. My issue appears to be in the power amp section as I have acceptable audio taking the preamp out to an external amplifier.Comment
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