Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums > The Basement

Spilled Drink Goo

(1/6) > >>

W. Mark Hellinger:
Any tips on cleaning/removing spilled drink goo from an amplifier PC board?

Here's what's up:  I have a new to me used Mesa Express guitar tube combo amp that has issues.  It's like the two channels are intermingled in ways they're not supposed to be.  Ch. 1 doesn't pass signal, but rather produces a steady 400hz (?) screaming feed-back-ish "tone".  Ch. 2 passes signal, but is unaffected by its' gain pot.  This amp has a good handful of DPDT relays and JFETS that do the channel and voice switching, which the symptoms suggested one or more of those devices were goof-ball ... so I poked around some, removed and tested a few of the most likely suspect components and all checked out fine.  And then in a moment of unusual clarity I noticed a line of goo under the PC board on the metal chassis... rather looks like semi-dried margarita or a daiquiri.  And sure-enough it's slathered all-over the PC board.  And looking closely, yes many of the component leads are a bit corroded... not growing green moss yet, but rather sporting a nice caramel glaze.  I have no-doubts this situation is shorting all kinds of stuff... might not be the only problem, but it's no-doubt a major contributor.  So clean that gunk off, reassemble and see what then... but how to clean?  I'm thinking a gentle scrubbing with hot soap and water and a tooth brush... then blow it all off good and let it cook next to the woodstove for a day.  Some suggest "contact cleaner", others suggest alcohol.  Eh?

Tim McCulloch:

--- Quote from: W. Mark Hellinger on February 19, 2024, 11:37:33 AM ---Any tips on cleaning/removing spilled drink goo from an amplifier PC board?

Here's what's up:  I have a new to me used Mesa Express guitar tube combo amp that has issues.  It's like the two channels are intermingled in ways they're not supposed to be.  Ch. 1 doesn't pass signal, but rather produces a steady 400hz (?) screaming feed-back-ish "tone".  Ch. 2 passes signal, but is unaffected by its' gain pot.  This amp has a good handful of DPDT relays and JFETS that do the channel and voice switching, which the symptoms suggested one or more of those devices were goof-ball ... so I poked around some, removed and tested a few of the most likely suspect components and all checked out fine.  And then in a moment of unusual clarity I noticed a line of goo under the PC board on the metal chassis... rather looks like semi-dried margarita or a daiquiri.  And sure-enough it's slathered all-over the PC board.  And looking closely, yes many of the component leads are a bit corroded... not growing green moss yet, but rather sporting a nice caramel glaze.  I have no-doubts this situation is shorting all kinds of stuff... might not be the only problem, but it's no-doubt a major contributor.  So clean that gunk off, reassemble and see what then... but how to clean?  I'm thinking a gentle scrubbing with hot soap and water and a tooth brush... then blow it all off good and let it cook next to the woodstove for a day.  Some suggest "contact cleaner", others suggest alcohol.  Eh?

--- End quote ---

Sugar is the enemy.  Warm water, mild soap, distilled or deionized water rinse.  Usually it eats through the PC board traces and attacks component leads.

Jim Thorn:
Mark,

I've always used denatured alcohol and a tooth brush for removal of flux from circuit boards, followed by a water rinse and blow dryer.  It has worked with miscellaneous goo, also.  Never had a problem.


--- Quote from: W. Mark Hellinger on February 19, 2024, 11:37:33 AM ---Any tips on cleaning/removing spilled drink goo from an amplifier PC board?

Here's what's up:  I have a new to me used Mesa Express guitar tube combo amp that has issues.  It's like the two channels are intermingled in ways they're not supposed to be.  Ch. 1 doesn't pass signal, but rather produces a steady 400hz (?) screaming feed-back-ish "tone".  Ch. 2 passes signal, but is unaffected by its' gain pot.  This amp has a good handful of DPDT relays and JFETS that do the channel and voice switching, which the symptoms suggested one or more of those devices were goof-ball ... so I poked around some, removed and tested a few of the most likely suspect components and all checked out fine.  And then in a moment of unusual clarity I noticed a line of goo under the PC board on the metal chassis... rather looks like semi-dried margarita or a daiquiri.  And sure-enough it's slathered all-over the PC board.  And looking closely, yes many of the component leads are a bit corroded... not growing green moss yet, but rather sporting a nice caramel glaze.  I have no-doubts this situation is shorting all kinds of stuff... might not be the only problem, but it's no-doubt a major contributor.  So clean that gunk off, reassemble and see what then... but how to clean?  I'm thinking a gentle scrubbing with hot soap and water and a tooth brush... then blow it all off good and let it cook next to the woodstove for a day.  Some suggest "contact cleaner", others suggest alcohol.  Eh?

--- End quote ---

John Roberts {JR}:
another vote for alcohol....

JR

Chris Hindle:

--- Quote from: W. Mark Hellinger on February 19, 2024, 11:37:33 AM ---Any tips on cleaning/removing spilled drink goo from an amplifier PC board?

Here's what's up:  I have a new to me used Mesa Express guitar tube combo amp that has issues.  It's like the two channels are intermingled in ways they're not supposed to be.  Ch. 1 doesn't pass signal, but rather produces a steady 400hz (?) screaming feed-back-ish "tone".  Ch. 2 passes signal, but is unaffected by its' gain pot.  This amp has a good handful of DPDT relays and JFETS that do the channel and voice switching, which the symptoms suggested one or more of those devices were goof-ball ... so I poked around some, removed and tested a few of the most likely suspect components and all checked out fine.  And then in a moment of unusual clarity I noticed a line of goo under the PC board on the metal chassis... rather looks like semi-dried margarita or a daiquiri.  And sure-enough it's slathered all-over the PC board.  And looking closely, yes many of the component leads are a bit corroded... not growing green moss yet, but rather sporting a nice caramel glaze.  I have no-doubts this situation is shorting all kinds of stuff... might not be the only problem, but it's no-doubt a major contributor.  So clean that gunk off, reassemble and see what then... but how to clean?  I'm thinking a gentle scrubbing with hot soap and water and a tooth brush... then blow it all off good and let it cook next to the woodstove for a day.  Some suggest "contact cleaner", others suggest alcohol.  Eh?

--- End quote ---

As others have said, denatured alcohol, warm soapy bath.  Problem, mixed drinks are more insidious than beer. It eats through electronics pretty quick. Depending on how long it's been there, even if you get some semblance of working, it may not be for long before it rears up again.  Personally, I'd take a stab at it, but just be clear that it may be going to boogy heaven sooner than later.  IF you could get it into Bob Leonard's hands.....
Chris.

Navigation

[0] Message Index

[#] Next page

Go to full version