GTB and Water...

[tymill]

I'd thought I'd cooked my GTB at EPR tihs weekend in the rain.

However I did some testing with my other GTB, and it turns out that only the switch is faulty! phew...

Has anyone had any luck reviving the little orange switch if one gets wet? it seems as if it's just a few components in there and no real amps passing through it so I can't imagine that it'd have been physically melted or blown out.

I'm trying rinsing it out with lots of clean water and putting it on the radiator to dry it out thoroughly. Is this in vain?

Hmm.

Any reflections of your experiences would be apprecited!

Moreover.... if anyone's got an extra switch laying around from a blown GTB perhaps... I'd deffo be interested! please just drop me a PM...

Cheers,
Ty

[sparrow.2]

You could try rinsing it in brake cleaner. Alcohol attracts water and dries off without residue.

[mark christopher]

or wd40
wtf are you washing electric componets in water for? do you take your mobile in the bath

[tymill]

Originally Posted by mark christopher

or wd40
wtf are you washing electric componets in water for? do you take your mobile in the bath

Well, the water, itself, is an insulator should just evaporate away quickly if it's heated. Problem is the mud and/or salts etc in the splashed up rainwater that might be causing shorts, etc. Or corrosion if that's already set in.

Main concern was that if the water from the race had started to corrode some components already, it would have all been a bit futile.

A few months ago I had a receiver start to do strange things, and when I examined it there was fine rusty corrosion on the pcb. Hmm.

Anyway, I'm using the past tense about the switch now... Somewhat foolishly, I'd just tried immersing it in a water solvent (acetone) to clear it out and it killed the plastic and the rubber insulation on the wires altogether. oops.

My bad, really, as I should have known that the orange plastic was polystyrene, which dissolves into acetone leaving a slimy goop. I just had year 10s make slime by putting PS cups in acetone for a practical about polymers a few weeks ago!

[MatJohnson]

Pure water doesn't conduct electric, Its the impurities that conduct the electric and break to components

Although, pure water is impossible to get so its kinda pointless.

[jim76]

Originally Posted by tymill

I just had year 10s make slime by putting PS cups in acetone for a practical about polymers a few weeks ago!

geez, they let school kids play with that stuff? It's ridiculously toxic and carcinogenic isn't it? and the fumes......

[SlowOne]

I've got some excellent pure water concentrate - just add water and stir!!

Best regime I've found for these situations is to put the affected part in the airing cupboard for a week, and then test it. My success rate is very high! Problem these days is not the components, but the very (very!) thin bits of circuit board that connect them. A very small current traveling the wrong way can burn them out easily.

Too late this time, maybe try that next time? HTH

[jim76]

yeap, airing cupboard for an extended stay usually does the trick. mainly when you have water in the sensors on motors etc

[mattlynch]

i would soak it wd40 ( as mentioned above) or similar then leave it somewhere quite warm for a few days on a bit of kitchen type paper, water will corrode the switch contacts and cause a loss of connection, wd40 or similar will stop this happening while it dries and will protect it for future wet drives , i drive in the wet all the time and this has never let me down. hope it comes back , that particular shade of orange is usually quite expensive.

[tymill]

Originally Posted by jim76

geez, they let school kids play with that stuff? It's ridiculously toxic and carcinogenic isn't it? and the fumes......

Using quite dilute acetone, it's a pretty standard practical: http://www.sciencemuseum.org.uk/educ...ing_slime.aspx

The kids love it!

Acetone is not terribly toxic and has not been shown to be carcinogenic... http://www.inchem.org/documents/icsc/icsc/eics0087.htm We do follow all the CLEAPSS guidelines for its use in schools though.

Nevertheless it does a pretty good job on Novak plastic!

Oops.

Cheers,
Ty

[Dazzler]

Dip into your pocket, buy one and put this all down to experience

https://demonpowerproducts.co.uk/pro...oducts_id=2868

[mark christopher]

Originally Posted by tymill

Well, the water, itself, is an insulator should just evaporate away quickly if it's heated. Problem is the mud and/or salts etc in the splashed up rainwater that might be causing shorts, etc. Or corrosion if that's already set in.

Main concern was that if the water from the race had started to corrode some components already, it would have all been a bit futile.

A few months ago I had a receiver start to do strange things, and when I examined it there was fine rusty corrosion on the pcb. Hmm.

Anyway, I'm using the past tense about the switch now... Somewhat foolishly, I'd just tried immersing it in a water solvent (acetone) to clear it out and it killed the plastic and the rubber insulation on the wires altogether. oops.

My bad, really, as I should have known that the orange plastic was polystyrene, which dissolves into acetone leaving a slimy goop. I just had year 10s make slime by putting PS cups in acetone for a practical about polymers a few weeks ago!

im struggling to see how that works in bold.

water is an insulator out of curiosity, what water did you use?

[DaSloth]

Not a problem as long as it deionized water. I dont think i would sit in a bath of it with a toaster though

Low voltages would be ok though.

[tymill]

Originally Posted by mark christopher

im struggling to see how that works in bold.

water is an insulator out of curiosity, what water did you use?

No prob, I can try to explain.

Electrical current is the movement of charge carriers through something. E.g. electrons moving through copper wire.

In metals, there are lots and lots of electrons floating around that are not tied to any particular atoms - they can easily move from atom to atom within the piece of metal. They are all negatively charged. If a pair of positive and negative electrodes are touched to the metal - these electrons are attracted to the positive electrode. And when they move - current flows!

In pure (or even pretty pure water like tap water) there are very few charge carriers around. Unlike metals, where there are millions of atoms all put together in a big mass sharing each other's electrons, water forms molecules. Each molecule is a "bundle" of 1 oxygen and 2 hydrogen atoms. This tightly-bound bundle has the same number of negatively-charged electrons and positively-charged protons in total in it - so it's neutrally charged. The molecule "could care less" if there were electrodes inserted into the water, as it wouldn't be drawn to either of the two. Hence, current does not flow.

In _salty_ water, there's are lots of charged ions floating around as well as water molecules (e.g. Na+ and Cl- if you dissolved table salt into water). These ions can also be attracted to their oppositely charged electrodes and move - causing current.

Of course this is a bit of a simplification, but basically water is a pretty good insulator at normal voltages. Sea water, no. Muddy water, no. But fresh water or tap water, yes.

As you know, you can even run a brushed motor no problem underwater, power leads and all!

Ok, I'll get off the soap box now... still doesn't change the fact that my switch is melted into goo!

Cheers,
Ty

[dodgydiy]

if you get something wet in dirty water, wash it immediately with clean water, spray it out thoroughly with a water repellant cleaner like fospro or any other decent electrical contact cleaner and airing cubd it for a few days. if its just wet, keep it wet until you can spray it out, otherwise it will start to corrode quickly

[TonyM]

Re water conductivity. Unlike metals, the resistance of water varies dramatically with the distance between two conductors and hence the volume of water in between. Check this out with a glass of water, with your meter on ohms slowly bring the two probes together. You will see that resistance rapidly reduces from MegaOhms a few inches apart to hundreds of ohms before the probes touch. So where you have very short gaps between circuits on a printed circuit board a drop of water will act as a short.

The actual readings will of course depend upon the purity of your tap water. One thing we can be certain of is that water picked up off a race track surface will undoubtebly be far from pure and will act as a damn good conductor..