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Old March 30th, 2014, 03:21 PM   #8 (permalink)
andyacecandy
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Quote:
Originally Posted by Rukbat View Post
1) You don't need rice to "dry off" alcohol. Alcohol is hygroscopic - it dries the phone better than rice (or even fresh silica gel). You use rice after an alcohol bath to absorb the last few molecules of water that the alcohol didn't absorb.

Oh, distilled water? That just destroys the phone slower than dirty water. It still soaks into the board, eventually causing carbonization and shorts. Whoever came up with that idea should be soaked in it - for a few years.

2) The big problem here isn't the water, it's the hydrochloric acid in the pool. (Chlorinated water has a very small amount of HCl in it, because the chlorine combines with the water.) HCl is a very weak copper etchant. You don't want to use it to make printed circuit boards (you'd wait days for a board to etch), but it will etch copper. Drying the board doesn't remove the HCl, it only evaporates water.

(It's the same reason I'd never accept a phone that was dropped into the ocean for a repair attempt. Too many acids eating away at the phone for there to be any hope of saving it, unless it was dropped into alcohol immediately after being dropped into ocean water for a second or two.)

Let's hope that the phone is still working in June. But just in case anything like that should ever happen again, read Wet Phone Taking the phone apart and scrubbing it with alcohol (which you did) is even better than just swishing the closed phone around in it. But use something softer, like the alcohol swabs you can get at CVS, wrapped around the pointed end of a wooden toothpick. You can scrub very fine copper lines off the board with a toothbrush.

BTW, 99% alcohol becomes anywhere from 96% to 90% as soon as you open the bottle, depending on how much water there is in the air for it to absorb (IOW, how humid it is). That's why there's no such thing as 200 proof Everclear. The 190 proof (95% alcohol) probably starts off closer to 200 proof, but by the time it gets into the bottle it's diluted with humidity.

But even 70% is enough. You want only 2 things from the alcohol - a lot of liquid (to both wash off any solids and to dilute any liquids and wash them off) and water absorbtion. While pure (100%) alcohol might dry the phone faster, 70% will still absorb all the water on the board if you give it a few changes. (And considering the cost of alcohol, you'll get change of a $5 bill for all the 70% alcohol you'll need to fix a few phones.) We used to buy it in 5 gallon containers in my cellphone stores (it's a lot cheaper that way - cheaper than bottled water), but used 70%, because you can dispose of that at the town dump. 90% or greater is considered a hazardous waste, and you have to pay a company that disposes of hazmats a lot of money to come down and pick up even a pint of it. And I never lost a phone because the alcohol wasn't strong enough.

(Please don't dump rubbing alcohol down the drain if you're not connected to a sewage treatment plant. It leaches into the ground, killing anything that takes it in - like bugs and the birds that eat them - and cats that eat the birds. BTW, it's deliberately poisoned to allow it to be sold without charging the "sin tax" that's collected on "drinkable" alcohol. There are various ways different manufacturers do it, but most of them cause it to be highly toxic.)

Thanks for the info!

Looks like I may have pressed my luck though. I tried the isopropyl trick again and dried off with a paper towel then in the rice. The phone turns on, the LED light works and the speakers work.... however the screen remains black. Wondering if I screwed something up by just putting it in isopropyl? Should I just put it back in the rice? Maybe something involved with the screen is not fully dry?
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