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Author Topic: Cleaning Circuit Boards
Jeremy Weigel
Phenomenal Film Handler

Posts: 1062
From: Edmond, OK, USA
Registered: Mar 2007

 - posted 01-04-2011 01:09 AM      Profile for Jeremy Weigel   Email Jeremy Weigel   Send New Private Message       Edit/Delete Post 
Is 100% denatured alcohol safe to use for cleaning circuit boards? I have several amps that were previously used in small bands and have accumulated cigarette tar on the circuit boards and cables.

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Tony Bandiera Jr
Film God

Posts: 2914
From: Moreland Idaho
Registered: Apr 2004

 - posted 01-04-2011 01:19 PM      Profile for Tony Bandiera Jr   Email Tony Bandiera Jr   Send New Private Message       Edit/Delete Post 
Yes and no.. [Big Grin]

It will remove the cigarette tar, but may also remove any protective coatings on the board and components, as well as forcing the tar into any components that are not sealed well (Old resistors, capacitors, etc.)

You will also need a boat load of it, as you MUST make sure ALL tar residue is removed as any that is dissolved by the alcohol and left behind may become conductive due to dirt being mixed in.

There are other solvents that would be safer (and non-flammable) but for the life of me I can't recall any brand names. I know that a form of Freon was used in the past, but it's illegal now.

A Google search for "electronic cleaning solvents" might prove helpful.

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Scott Norwood
Film God

Posts: 7907
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

 - posted 01-04-2011 05:58 PM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
What about "contact cleaner" and/or "tuner cleaner"? Would these be safe?

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Jake Spell
Master Film Handler

Posts: 294
From: Johns Island SC
Registered: May 2009

 - posted 01-04-2011 06:57 PM      Profile for Jake Spell   Email Jake Spell   Send New Private Message       Edit/Delete Post 
For reference only, it was R-11(Trichlorofluoromethane). And you are correct that it is illegal to use due to it being a cfc refrigerant and depleting the ozone layer. It did however clean very well and left no residue and since it was one of the few refrigerants that was liquid at room temperature it was widly used in labs for cleaning purposes.

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Dave Macaulay
Film God

Posts: 2000
From: Toronto, Canada
Registered: Apr 2001

 - posted 01-07-2011 11:06 PM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
For smoke tar I like stuff called "Spray 9", nothing else I've come across takes it off as well. It's water based and doesn't eat plastic or remove most component markings.
If I'm worried about water contamination then isopropyl alcohol (pure 99%, not rubbing alcohol compound) is good. Non-flammable brake cleaning spray is pretty safe, but it takes the markings off some components. The flammable brake cleaning spray attacks some plastics. I don't like ethanol or methanol as a cleaner, methanol takes a lot of markings off and oftrn leaves a milky residue, ethanol just doesn't work as well as isopropyl. None of these really dissolves smoke tar as well as Spray 9 in my experience. I've had to clean old projection equipment that spent decades with chain smoking projectionists, it's fun discovering what original factory color is hiding under the yellow coating. Kneissley used some fancy stuff for their knobs and handles.

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Marco Giustini
Film God

Posts: 2532
From: Reading, UK
Registered: Nov 2007

 - posted 01-09-2011 06:10 AM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
Electrolube Cleanser. Non solvent, it's safe for you and do a darn good job.

Wash the boards like you were washing dishes and rinse with tap water, the result will be amazing. My boards were full of sigarette tag and oil. Eventually they were simply brand new.

You need to bake the boards in a oven (low settings, dunno how much) or let them rinse thoroughly before using them again. I blow them with clean compressed air and let them rinse in a dry place for 2 weeks before using them again.

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Louis Bornwasser
Film God

Posts: 4410
From: prospect ky usa
Registered: Mar 2005

 - posted 01-09-2011 06:18 AM      Profile for Louis Bornwasser   Author's Homepage   Email Louis Bornwasser   Send New Private Message       Edit/Delete Post 
Remember that not all components are water-safe. Many are inserted after the board is processed when new. Examples are switches and some connectors.

Compressed air is a good idea. We leave then in the sun for 4 or 5 hours and then wait overnight before powering up.

Standard procedure for old IREM rectifiers, too. Louis

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Tony Bandiera Jr
Film God

Posts: 2914
From: Moreland Idaho
Registered: Apr 2004

 - posted 01-09-2011 01:46 PM      Profile for Tony Bandiera Jr   Email Tony Bandiera Jr   Send New Private Message       Edit/Delete Post 
Scott: No and hell no!! Both are way too harsh for general cleaning, and both leave behind residue (which "lubes" the contacts) which would attract dust and are conductive.

Jake: Thanks, that was the solvent I am thinking of!!

Dave: Good suggestions (except the brake cleaner, every one here in the US I am aware of really attacks plastics). Is the "Spray 9" available outside of Canada?

Marco: That sounds like it would do the trick. To dry out in the oven would be a great idea, a temperature of 150-175 degrees f overnight, plus a day of room temperature drying.

When rinsing the boards, DO NOT get ANY water on/in power transformers!! (For cleaning a transformer use a rag and the solvent ONLY.) They never dry out properly (in short dry times/oven) and generally fail on power-up.

Larger transformers like Louis' rectifiers can be carefully solvent cleaned and rinsed, but only in extreme cases. They are better "dry-cleaned" by using a special cleaner made for electric motors.

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