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My Rx got a little wet.

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Old 05-18-2003, 11:09 PM
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m.gramling
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Default My Rx got a little wet.

this happened yesturday. My Hitec Rx got a little moisture in it. I landed in the middle of a mud puddle at our field.

I picked the plane took it back to pitts. I started it up, and noticed that only my aileron servo was jittering. So I let it set their and idle for about a min. or 2. trying to figure out my problem.

So I took the Rx out, and took the cover off. And noticed my Rx had a little moisture in the cover. So I wiped it off, and packed up my stuff for the day.

So it has been over 30+hours since this has happened. I let the Rx air out over night with the cover off, I will probably let it do that for another night or so.

do you think I toasted my Rx.
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Old 05-19-2003, 12:21 AM
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Default My Rx got a little wet.

First of all, let me qualify this by saying that I work with electronic instruments in ocean water all the time.... I think I have a 'clue' as to what might work and what might not.

Even though this isn't salt water, the puddle you dunked this into has mud and other contaminants in it. These contamints might be shorting out the traces or components on your rx board. This is probably what might be causing your problem.

DO NOT apply power under any circumstances to 'see if it's fixed'. You could be doing further damage.

I'd clean the board as best I could (you can get distilled water from the drug store to rinse it as clean as possible), then send the rx off to a repair facility. I would consider the rx very unsafe until professionals checked it out. Tell them exactly what happened, and what you did to minimize damage.

There are a lot of places for moisture (and contaminants) to hide inside a rx under the components and inside tuning slugs, etc. Remember, it's not the water that causes problems, it's the contaminants in the water. PURE water is almost an insulator...

Yes, it's possible that the rx could dry out and not cause you any more problems. That is, until the next humid day. Then, it's a crap shoot.

Take the circuit board out of the case. Take a CLEAN toothbrush (used is OK, with soft bristles) and run some water over the printed circuit side. Brush it with the brush to clean it. If you got contaminants on any of the lands, it could be conductive and causing some of your problems.

I'd hold off on rinshing the component side only because the components are so close together, you might do more damage than good. And, if there are any hollow components (tuning slugs, etc) that were dry before, you'd get water in them now.

If you had access to PURE water (not tap water) you could try using that for rinsing the board off. You might find distilled water at the drug store. Rinse the board and let it dry.

What you are trying to do is to flush anything that might be corrosive off the board. I strongly recommend that you do NOT stop here and try to fly with this rx. You still do NOT want to apply power. You could still smoke the rx.

At this point, you might want to send the rx off to a repair facility with a description of what happened and what you did.

Only as a suggestion, I have sent some of my receivers to Radio South after a crash for a checkout. They're at radiosouthrc.com and I've been happy with my dealings with them. They could give you an estimate (I'm guessing that they'd charge you a diagnosis fee), but you might get your receiver back in like-new condition for less than the cost of a new one. And they thoroughly test the rx while they're repairing it.

Just my thoughts..

Bob
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Old 05-19-2003, 01:13 AM
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Default My Rx got a little wet.

N1EDM has given you a great answer to your dilemma, and I have done the same thing on occasion.

What I do now, however is to simply spray the affected part with contact cleaner. It is Tetrafluorothene and is inert. It drys within seconds and you can spray a live board with it.

If you notice heavy, foreign material you can also use a toothbrush with the spray to clean the board. Immediately after you've sprayed it with this you can safely apply power and test. Also you can spray the traces and the components, too.

I think you may find it at Radio Shack, but Mouser, Grainger, Digikey also carry a form of it.

I also recommend that you return it to the manufacturer, or competent repair facility before using it again, even it if appears to work properly.
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Old 05-19-2003, 03:38 AM
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Default My Rx got a little wet.

Good point, Crash_n_Burn. I should have thought of that myself... it's not like I haven't used the stuff. I think I answered that post too quickly.

I'm a little biased against the Radio Shack stuff though.. I think it leaves a residue of its own, but can't prove it. Mouser, Grainger, and DigiKey are also good sources, as you point out.

Still, if the R/S stuff is all you can get, it's a good idea.

Thanks for reminding me...

Bob
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