sco77
Junior Member
Posts: 66
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Post by sco77 on Jan 4, 2022 9:00:09 GMT -7
Got some crackles and volume jumps on my MAZ 18. I've watched the Doc's AMA on maintenance and am chasing down my screwdriver, etc. IIRC, the Doc said the caps would discharge if you turn off the power while playing a chord or something. Is this the case or did I just imagine it. I'm looking to make sure that the caps are sufficiently discharged so I don't get surprised while cleaning/tightening things.
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Post by Chilly Gibbons (Todd T.) on Jan 4, 2022 10:36:56 GMT -7
Do you have a multimeter handy. I always test the voltage before either discharging the caps or just dive in if already discharged. I think the idea is to turn the power off without touching the standby switch and play a chord and listen to the caps dissipate their stored voltage. I still test though. Once bitten, twice shy.
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Post by purpletele on Jan 4, 2022 10:39:28 GMT -7
Got some crackles and volume jumps on my MAZ 18. I've watched the Doc's AMA on maintenance and am chasing down my screwdriver, etc. IIRC, the Doc said the caps would discharge if you turn off the power while playing a chord or something. Is this the case or did I just imagine it. I'm looking to make sure that the caps are sufficiently discharged so I don't get surprised while cleaning/tightening things. That is correct! If you hit a chord and turn the power off you will hear the notes fade out. That should drain the caps for you and make the amp safe. Volume jumps may be the power tubes ready to fail, which could take out the rectifier (LIkely), or a grid resistor (Unlikely). Crackles could be Pre-amp tubes or Pots that need to be tightened or cleaned up with Deoxit. Good luck
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Post by Don A on Jan 4, 2022 11:57:25 GMT -7
Make sure the amp is warmed up enough to make sound when you do this- don't just flick it on then right off. I know this seems silly to mention, but it won't drain the caps if the tubes aren't drawing current.
I'd still measure the voltage at the caps and on the plates with a DMM after following this shutdown procedure.
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Post by DRZ on Jan 4, 2022 12:33:24 GMT -7
After playing the amp. Turn off the Power switch, BUT leave the Stand-by in the play position. This will leave a path from the Output Transformer to the Load ( i.e. Speaker ) and will drain the power caps. Wait a few minutes , unplug from the wall and still be very careful if your not familiar with the inside of a tube amp. Legal disclaimer " No servicable parts inside "
Z
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