Keep liquids off electronics - and what happens when you don't

[KarenColumbo]

Dear all!

I have a question that's not entirely concerning DIY - but I'll ask anyway:

A friend has a very sophisticated pedalboard for hie bass. Last night some idiot poured beer on it.

Now the situation is like this:

- if he connects three pedals in a chain (ANY three pedals and ANY combination of these) there's hiss (-50dB).
- if he just connects ANY single pedal, there's no hiss at all.
- no hum at all in any combination
- his power supply has 8 outputs in 2 groups. switching the groups does not change the above situation
- cables were all replaced

Could you help me uncover a (prombably simple) solution to this conundrum?

[EBK]

A friend has a very sophisticated pedalboard for hie bass. Last night some idiot poured beer on it.

You are not the "friend" or "idiot" in the story, right?   

I'd say completely disassemble everything and clean it with alcohol (the non-beer kind).  Then reassemble and test. 

[KarenColumbo]

A friend has a very sophisticated pedalboard for hie bass. Last night some idiot poured beer on it.

You are not the "friend" or "idiot" in the story, right?   

I'd say completely disassemble everything and clean it with alcohol (the non-beer kind).  Then reassemble and test.

In this case I'll admin nothing But no, I'm just the messenger.

[GibsonGM]

Turning on electrical devices after they get wet is a No-No...that is when the damage occurs...

[digi2t]

How come the busty blond in the front row never gets the beer? Why is it always the pedalboard that eats it? Is this some sort of "butter side down" phenomenon?

[R O Tiree]

Switches and pots are going to be the stoppers.  Very difficult to clean them out and they've often got a dab of grease placed in there at assembly time to lubricate the mechanisms, and that will need to be replaced as well... or just get new pots and switches and replace them on spec?

[EBK]

Switches and pots are going to be the stoppers.  Very difficult to clean them out and they've often got a dab of grease placed in there at assembly time to lubricate the mechanisms, and that will need to be replaced as well... or just get new pots and switches and replace them on spec?

The switches and pots might be ok.  The beer could have passed over without getting inside, assuming the pedal wasn't inside a bucket when the beer spill happened.

[blackieNYC]

Hiss?  That's the carbonation. It will flatten out. 😈

Very weird. Are there "digital" things?  Some circuits - with a lot of surface mount stuff - can have multilayer boards with weak thru-hole connections. I've seen sugars or acids from soda or coffee eat away at thru-holes in such a case.
Try a different power supply and DC daisy chain cable?  Maybe it has been weakened and can't handle that third pedal?  Maybe you have already, but "drop" your observations thus far (for the heckavit) and come up with a different systematic approach. The pedals can't all be faulty.

[stallik]

How wet did the power supply get? Worth subbing it for another just to check

[amptramp]

You don't have to worry about FET's getting wet - they have a drain.  Bipolar transistors do have a problem because they have a collector that retains moisture.  And of course pots have a problem - they have been used to contain water for millennia.  Condensers take the moisture right out of the air, so they can overload even if the liquid moisture doesn't quite reach them.  Tubes carry water and if you live in an area where they call tubes valves, it's still the same.

[thermionix]

One tiny drop of beer on a hot EL34, and show's over folks.  Ask me how I know.  (Dammit Johnny!) 

[KarenColumbo]

Heh, thank you all for the beverage related bonmots - this made my day.

We tried everything including borrowing a power supply unit.
After tinkering around and trying all possible combinations of FX pedals and PS the hiss suddenly was gone - in the original setup, too.
So it's cleaning out each and every stompbox and praying to an alcoholic god that this was it.

I was just puzzled by the fact that there was hiss instead of hum and thought I could pinpoint the problem by thinking about gain mishaps and such.
So we had a few brews in safe distance from the battlefield and had a good think about it.

Then we had a rehearsal and now can reluctantly close this case. It's an accident waiting to happen, though. But isn't everything?

[marcelomd]

Hi,
Liquids can bridge contacts sometimes, depending on quantity and composition. Beer is full of electrolytes (one reason it is good for you). If it got inside potentiometers it could measure with the value and taper. Once dry, everything works again.

But, once dry, beer will leave a residue that may be conducting enough to cause noise. This residue is acidic, meaning it can damage the circuit parts. Any remaining moisture may corrode metal parts and contacts. Open the pedals to clean them if you can, just to be safe. Isopropyl alcohol is good.

I did my internship with the engineering department of a hospital. One time I got a heater-humidifier that wasn't working. It's a device that has a hot plate to heat water for a ventilator, so it doesn't dry the patient's airways. Anyway, someone thought it was a good idea to heat coffee on it... The coffee spilled inside and ATE every metallic part that came in contact.

[Rob Strand]

I was just puzzled by the fact that there was hiss instead of hum and thought I could pinpoint the problem by thinking about gain mishaps and such.

The beer could bridge an input to an output and make it oscillate which often is heard as hiss.
The puzzling thing to me is why it only produced the hiss with combinations of three effects.  The key would be why that was happening. There might be a pattern or something common, like a lead,  in the test set-up which wasn't obvious at the time.

If you cleaned it out then there's a good chance you won't have any side effects in the future.  Well, unless beer got inside of something that wasn't cleaned.

[stallik]

Clearly, the board was suffering from a hangover. If you listen carefully, it might be saying something like 'never again'

[DIY Bass]

Best/worst liquid accident I have seen was in an old style CRT TV.  You see, a rat got inside, and then got fried.  So far, not actually a problem, but over time the rodent liquified, and liquid rodent dropped down onto a circuit board.  The TV stopped working.  I never want to see or smell anything like that again.

[thermionix]

liquid rodent

I was just mentioning in the Pictures thread that I plugged my Rat clone into my newly completed CE-2 clone.  Liquid Rodent is a good name for the combo.  Doesn't smell too bad either.

[stallik]

Best/worst liquid accident I have seen was in an old style CRT TV.  You see, a rat got inside, and then got fried.  So far, not actually a problem, but over time the rodent liquified, and liquid rodent dropped down onto a circuit board.  The TV stopped working.  I never want to see or smell anything like that again.

I was called to photograph an incident where a cat sheltered from the rain in the mains supply box to a hospital. In the Middle East, safety regulations permitted the brick switchgear hut to be placed on stilts with free access from underneath. The cat didn't survive but it wasn't the cat I was asked to photograph. It was the guy who tried to remove it without cutting the power.

[anotherjim]

Does Schrödinger know this? Or was he the guy you had to photograph?

[EBK]

Does Schrödinger know this?

Yes and no.