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Thread: water damage pedal

  1. #1
    Senior Member Garydean's Avatar
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    water damage pedal

    A friend of mine brought me a H&K Rotosphere pedal for repair. PCB transistor...

    He dropped it into a pail of water by accident, it was not plugged in at the time. He said it turns on but eats up the 12ax7 almost instantly. Is it toasted or would it be repairable. Figured I'd ask before I opened it up and start testing the circuit. I know some things can be saved if it's dried out soon after the dunk.

    Thanks,
    Gary

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  2. #2
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    Sounds like he plugged it in to "see if it still works", before drying it out completely.

    I'd open it up and look for carbon tracks where the board or components have been arcing before doing anything else.

    Anything is repairable, but whether the time/cost factor makes it worth it is up to you and the owner.

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  3. #3
    Senior Member Garydean's Avatar
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    Thanks Bill for the reply. At a quick glance I see oxidation all over the place, pots and connections are white and chalky. I guess it wouldn't hurt to disassemble it and check it out. Typically what components will get damaged in this situation? This thing is loaded with DIPS, trim pots, diodes, zener diodes all kinds of stuff. Troubleshooting after a visual inspection would include using my scope, true? I've never scoped a beast of this nature.

    Gary

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    There are two types of damage to deal with here, first the damage from the liquid and then the damage from turning the unit on while still wet.

    It sounds like there may have been something corrosive in the water for that much oxidation to have occurred. Ask him what was in the bucket. If need be, you may have to wash out the board with soap and clean water to stop the corrosion. If you do this, make sure that everything is rinsed clean with running water. Then blot with clean paper towels to remove the excess moisture and finish with a hair dryer. The only thing I'd really worry about is the power transformer. It will require a thorough drying out before applying power.

    As for what was damaged by powering it up while wet, everything is to be inspected and is suspect for damage. Again the power transformer would be first on my list to check out. If it was still damp when powered up, it could now be a mass of shorted turns. Clean and lubricate all of the pots and switches, as they will rust themselves solid if not dealt with fairly quickly.

    I'd suggest powering it up in stages if you can. Trace out the power supply and remove all loads from the transformer, and see if it will power up with no signs of damage. Read the voltages and if all seems reasonable, hook up the rectifier and filter stages and see if everything is ok there. Then power up the entire unit and see what the symptoms are.

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  5. #5
    Senior Member Garydean's Avatar
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    Great stuff Bill. Thanks for all your time.

    Gary

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    Senior Member Garydean's Avatar
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    I spent about an hour, some deoxit and a can of air to clean the jacks and boards. Removed all ground points and scrubbed the rust off. Put it back together, tested and all is working 100%. Nothing on the board had shorted luckily. Just thought some peeps would like to know what the outcome was.

    Gary

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    Hey! Glad to hear that you got it up and running again.

    And thanks for the update, cause I learn stuff here all the time, and hearing what fixed something is always good information to know.

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  8. #8
    Senior Member Garydean's Avatar
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    Thank You Bill for your advice. My customer was poorly advised by another repair shop that he should "throw it away", "it can't be fixed".

    best regards,
    Gary

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    Lifetime Member Enzo's Avatar
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    The white residue was probably just scale - minerals in the water. Same stuff that leaves spots on your dishes. WOn't hurt anything. I doubt it was really "corrosion."

    Water won't usually hurt circuit boards. Transformers don't like it, but boards ore commonly wave soldered then run through a water bath to clean off the fluxes. For all the world this cleaner is about the same thing as a dishwasher in a restaurant. But water does hide under ICs and other parts, so it is important to get it all out before applying power. I usually tap the board firmly on its edge on the bench top to shake water out from under things. COmpressed air will blow it out from under things. Alcohol will mix with the water and then the whole combination will evaporate MUCH easier. And of course apply heat. An over set at 130 degrees, or just a warm dry room for a couple days.

    Powering it up when wet is a bad thing to do since water conducts, so you might as well sprinkle steel wool flakes all over the board. There is absolutely no predicting WHAT will be damaged by powering up when wet. The water will ignore any schematics. it will be random short circuits all over the board.

    Make sure any batteries are removed. Batteries turn the copper and parts into little anodes and cathodes, and your traces can slowly dissolve. Copper plating in reverse.

    I am convinced that "it can't be fixed," is usually translated as "I don't know how."

    I never tell someone a thing cannot be fixed, unless the board is crushed or something, or there is a darn good reason like this chip it needs is no longer available. Of course we DO discusss costs at this point.

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  10. #10
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    Dry everything out, fix any traces that are worn away.
    transformers are a problem if you have one, they hold water and need to be totally dried out before powering up.
    try baking it in an oven.
    A friend gave me a box of about a dozen water damged pedals.
    Alot of them were vintage pieces worth money so it was worth it to repair them.


    I jokingly asked my friend if the pedals I was fixing had been in hurricane Katrina.....he said yes!
    I wish he had told me, who knows what toxic stuff was in them.

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  11. #11
    Lifetime Member Enzo's Avatar
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    Hah! WHo knows what toxic stuff is caked on the typical floor toy from the average band?

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    I don't even want to think about that!

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    Beer in the Board

    Every 4 month I look at all the insides and clean them.

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  14. #14
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    Quote Originally Posted by Enzo View Post
    Hah! WHo knows what toxic stuff is caked on the typical floor toy from the average band?
    I don't use pedals live, just a foot controller for my rack unit....stays pretty clean.
    With the amount of repairs you do Enzo, I'm sure you've seen your fair share of weird things in amps and stuff as I come across!
    Rodent waste, dog food hidden in amps by rodents, rodent killer pellets, dirt, grime, filth....you name it!

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