Cleaning Old Soda Off Of A Circuit Board?

With dirty equipment I've found over the years that fancy alchohols and degreasers are a waste of time and money. The most effective cleaning method is to be brutal and use a mix of really, really hot water and washing up liquid dispensed by a pressure sprayer (one of those pump up things). Particularly bad patches attended to by use of a paintbrush. It's essential that a thorough rinse in clean hot water is given afterwards (pressure sprayer again), followed by drying at a high temperature (say 40degC) for as long a time as possible. Dishwashers can be even easier if the parts will fit in.

That's a big plus. I've fixed lots of equipment that's suffered drink spills (coffee, coke, wine, beer, etc), & the single biggest factor that determines whether it survives is how fast the power is removed & the gunk washed out.

Yes, absolutely.

If you're careful, it's a good idea. After you wash the board[s], you also need to wash in alcohol. The important thing is make sure that it's 100% dried out (gently!) before you next apply power. I put boards on a folded towel & sit them in a dry, warm (30-40c or so) place for at least 3 days to make sure that all the crevices (like under chips) are totally free of moisture. The alcohol helps a lot with this.

Go ahead. But you may need to replace the pots anyway.

--
   W  "Some people are alive only because it is illegal to kill them."
 . | ,. w ,      
  \\|/  \\|/              Perna condita delenda est
---^----^---------------------------------------------------------------

Use clean water with baking soda dissolved in it. Rinse off and let dry for a week.

** That is the EXACT method I have been using with 100% success for many years to clean PCBs and heatsink modules contaminated by drink spills or just accumulated grime blown in by a fan. ** Ain't got one of them.

Be neat to dump a whole power amp in one ....

....... Phil

On 15 Mar 2007 19:34:08 -0700, "phaeton" Gave us:

Microwave some 99% IPA up and give it a good hot alcohol bath.

Not assembled. Break it down into subassemblies, like the panel, etc.

Being hot, the IPS should dislodge the soda remnants and surupy slurry.

Then a good bake out in a 60C oven (140F). THEN, add the contact spray, which might have some dry lube in it for the pot shafts.

Otherwise, replacing the pots that are sluggish to turn would be a good step.

If you hot dip the PCB assy., keep from dipping any transformers or inductors as the tapes used will have their adhesive backings released, and the bake step above needs to be about a half hour, for a PCB where you did get a transformer "wet", it would need an hour bake.

On Fri, 16 Mar 2007 03:42:43 GMT, "Homer J Simpson" Gave us:

Bake for an hour at 60C.

That's going to make it fun.

Phil Allison wrote: #Be neat to dump a whole power amp in [a dishwasher] # Seems like that's what it might take

--if cleaning would work on all the bits. I'd brace myself for the probability that the panel-mounted parts will have to be replaced.

john@ jjdesigns.fsnet.co.uk wrote:

I agree with everything you have said ...except one detail:

A paintbrush has soft bristles. An *acid* brush

with the business end trimmed short for even more stiffness is the tool. Any place that sells industrial supplies (pastes) has them.

Wash it with carbonated water (club soda). That will get the water- soluble sugars off of it, which is what gums things up. The contact cleaner things are usually non-polar solvents, and sugar will just shrug that off. And blow it dry, don't bake it dry - baking leaves crud behind. With dry clean compressed air, the liquid water gets blown away and takes the crud with it.

I used to fix video games and pinballs that were located in bars - it's amazing what kinds of crud can get on boards in that kind of venue.

Of course, it's nothing like cleaning medical devices that have been dropped in a bedpan. =:-O

Good luck! Rich

On Sat, 17 Mar 2007 00:55:12 GMT, Rich Grise Gave us:

Blowing on it does remove any (most) solids as the water/solvent gets pushed off, but baking is STILL required. Especially for a water /"club soda" wash, as PCBs are hygroscopic.

Get a clue, grisetard.

On Sat, 17 Mar 2007 00:55:12 GMT, Rich Grise Gave us:

Funny, since the "boards" on a pinball are in the cabinet behind the backglass.

Funny, since practically all "medical devices" are immersible.

Lots of pinball machines have huge PCBs (& usually the PSU as well) directly under the playing field.

Lots of them are, but not "practically all".

--
   W  "Some people are alive only because it is illegal to kill them."
 . | ,. w ,      
  \\|/  \\|/              Perna condita delenda est
---^----^---------------------------------------------------------------

Well, actually, I've seen EM (electromechanical) pins that have point-to-point circuitry right on the bottom of the case, under the playfield, but the PCB ones usually put the PCB behind the backglass.

The problem is a lot more prevalent with stand-up and cocktail videos - but in either case, you'd be surprised where people can spill their drinks!

Big Dork simply has no clue - he's best left ignored.

Cheers! Rich

On Sat, 17 Mar 2007 20:52:18 GMT, Rich Grise Gave us:

So are you, asswipe. Upright video games and cocktail versions of upright video games are NOT pinballs, you retarded f*ck.

Yes, I've seen those too, although it's been quite a few years.

Nearly all the ones I've seen have PCBs behnd the backglass, & under the playing field.

I worked at an arcade for a while as a teenager, & nothing like that would surprise me. ;^)

--
   W  "Some people are alive only because it is illegal to kill them."
 . | ,. w ,      
  \\|/  \\|/              Perna condita delenda est
---^----^---------------------------------------------------------------

Well, I got it home. The preamp and power amp are two different boards connected by ribbon cable. Strangely, all the soda is on the power amp board in the back. Further investigation reveals that the amp was not 'on' at the time of the spill. It has been turned on since the initial cleaning, and that's how they know it sounds like crap. I haven't turned it on to try it out.

Lots of gunk everywhere, bridging traces and leads, but nothing looks burnt and black or anything.

In lieu of a pump-up pressure sprayer, would a DIY car wash gun work? Most of them have a 'low pressure jet' that's on by default, until you squeeze the trigger (for high pressure). How about if I saran wrap up the transformer and pots and hit it with the low pressure only, then rinse well, and let it sit up in a sunny place for a couple of weeks to dry out?

The sliders and knobs were really sticky and stiff, and I went ahead and blasted them with the Contact Cleaner. All but one slider improved in 'feel'. I'm going to let them sit a day or so, blast again, and then track them with an ohmmeter to see if they follow the curve like they should. If they don't, I won't be heartbroken.

Thanks for the help and suggestions thusfar.

-phaeton

It is not at all important that you blast the water in with any force. All you need is its ability to dissolve the sugars and slats left behind, and a simple stream will do that. So you should be able to use a low pressure stream and avoid dumping it through the transformer (unless it has soda run through it). The contact cleaner you have used will make it harder for the water to wet the surfaces originally contaminated, so you may have to start with a flow of water mixed with dish washing detergent to get under the oils in the contact cleaner.

When everything looks clean and just wet, a thorough drying is all that you should need to test the unit. Then, if the pots are noisy, a little contact cleaner might help lubricate them.

Don't use tap water or mineral laden drinking water. Use distilled water. If there is no plastic in the way, I chase the water with methyl alcohol then blow it dry.

Okay, that makes good sense. I had DI water available from a tap so it was never an issue. I also used nitrogen to dry the parts, also from a wall tap.