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September 07, 2025, 05:26:35 am
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Hoffman Amps Forum image Author Topic: Continuity between chassis ground and middle lug on volume pot in Super Reverb?  (Read 3236 times)

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Offline Searing

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as the title says.  It’s on both channels volume pots?  Middle lug.   Amp turns on, makes odd noises, volume is present even on 0.  I can’t find the issue?  Is it normal to have continuity between the chassis and the middle lug on the volume pot?  Can’t be!

Offline Deric

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If the volume pots are turned all the way down, yes that is normal.

Offline Tony Bones

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You mean with a multimeter set to buzzer mode? What were you hoping to learn by poking around with that thing?

Offline Searing

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I have signal even with the volume at zero.  And, static.

Offline shooter

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Can’t be!
put a gator-clip on center lug then ground to a really good ground, not a floating wabbly crappy one  :icon_biggrin:
Went Class C for efficiency

Offline Searing

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Ok.  It was a bad connection at V2.  But, now I am getting intermittent static when I push on the phenolic board.  Almost as though it is conductive?


And, whenever the dehumidifier in my basement turns on, the amp motorboats.  This is a Super Reverb.  I just recapped it.

Offline shooter

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Almost as though it is conductive?
welcome to old fender boards, pretty well know problem with only ONE good solution, replace it.  you can try separating the layer, elevating the board, insulating the layers, an on an on......................
Went Class C for efficiency

Offline Searing

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Insulated the top of the bottom phenolic board with some insulating tape.  Seems to have worked.  But, fuse kept blowing, and I saw the PI turn blue/white.  Turns out the socket is damaged as one of the pins is broken and jammed deep inside.  This amp was abused!  I increased the value of the resistors on the three 22uf main filter caps hoping this will stop the motor boating.  We shall find out once I get that new PI socket delivered.

Offline Willabe

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Insulated the top of the bottom phenolic board with some insulating tape. 

Ok, but, the eyelet board can be conductive from eyelet to eyelet, very common. 

Sometimes only certain sections/areas are conductive.

Offline Searing

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I figured out why the amp was motor boating....I hooked up the main caps wrong.  Rushing the job!  Need to SLOW down!

 


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