PCB Cleaning

[vintageampfixer]

I'm interested in how people clean up old equipment, especially circuit boards, that have become grimy with age through hot / cold cycles, dust, etc. Dirty circuit boards invariably don't do what they're meant to, particularly once any layer of dirt gets even slightly damp from moisture in the air so what's best out of:

Compressed air
Ultrasonic bath
Soap and water ....... !! ...... maybe not ideal for surface mount or pots, faders and switches

Other ideas welcome, of course

 

[totoxraymond]

I just repaired and cleaned an old dmx controller, i used:

Compressed air for big loads of dust.

Wd40 for rusty metal parts.

IPA (not the beer) for about everything else (pcb, caps, front panel...)

Thomas

 

[dom]

Isopropyl alcohol and a lint-free wipe (like kimtech) is usually OK for cleaning grime off of PCB surfaces and board-level components. Use a soft brush or compressed air to help break-up any difficult areas. Usually I use very mild soap and water to clean front panels since IPA there can sometimes cause paint or other markings to fade.

 

[JohnRoberts]

I had a business partner destroy a production run of PCB cleaning them off with a high pressure air hose... He literally blew water inside some film caps (polystyrene).

alcohol and an acid brush...

JR

 

[dom]

Yes, I don't think I've ever had a need or want to use a high pressure air compressor. Too many delicate things. Try to avoid mechanical stresses like that when possible. A compressed air can, IPA, wipes / soft brush and some time / elbow grease is generally sufficient.

 

[vintageampfixer]

Seems we're all taking roughly similar approaches!

I use compressed air up to about 50 PSI (~3 Bar) as my go-to for first pass cleaning of circuit boards. I've never blown any components off a board or damaged tracks ... yet ... although I'm cautious around relays, pots, etc. A dry paintbrush is great to gently work any tougher bits loose.

For cabinets, I tend to use sparing amounts of water with a mild soap, usually applied with a soft brush or a well wrung cloth.

I avoid all solvents unless I need to use one, then it's just whatever works, taking care not to spread it around too much because they tend to damage finishes.

In the days of valve TVs, I always used to Hoover them out - they were always full of dust, cobwebs and dead spiders, sometimes worse - and while I avoid TVs these days, I do find loudspeakers, particularly those used for gigging, often benefit from being very gently cleaned using a vacuum cleaner with a soft brush attachment.

Strangest thing I've ever found while repairing something was a dead frog inside a tower computer that'd been used in a barn for a while. The frog had expired on the network card and the computer had expired shortly afterwards!

Cheers all!

 

[Disco Volante]

I use the above methods too, plus: if the switches are noisy, a bath in a mild solution of citric acid will remove all the black oxidation without damaging the metal. Rinse with water and blow/vacuum dry. This has restored numerous vintage amps' switches and saved a ton of time and money sourcing those NLA switches, like in the Quad 33 etc. Always be careful even with mild acid around aluminium. I tend to remove the sensitive front panels before cleaning.
Cheers;-)

 

[Bjorn Andersson]

I use PRF 6-68 Cleaning Agent to clean pcb´s from dirt and flux

 

[vintageampfixer]

I use PRF 6-68 Cleaning Agent to clean pcb´s from dirt and flux

Thanks, that's a new one for me. I used to use trichloroethylene years ago ... quite effective although we found out later it's really quite a nasty chemical ... and it's now banned!

 

[Boomerang]

My bathroom bin has never seen an old toothbrush. They always find a new home in the workshop. Great with flux remover on PCBs and for cleaning stubborn muck that a paintbrush won't budge in old equipment. Even when completely knackered as a brush, they can be filed down into a handy pry tool.

 

[Script]

Don't have air compressor, so for dust sometimes just cold-air hair dryer outdoors for starters, together with a brush. Then, for very difficult to reach areas, sometimes straw with lung air.

For grime and sticky PCB, baked in solder flux and other residue I used to use isopropyl and a brush for long, but recently found a 'flux cleaner' in Japan containing methylene chloride or dichloromethane. Highly effective even on PCB with 40-years of nicotine tarnish.

That stuff is banned inside the EU, as far as I know. I use very sparingly, cos it's a somewhat nasty (unhealthy) chemical -- with a touch of lemon smell.

I use together with 70% ethanol-containing cleaning tissue (somewhat like baby-bum tissue but not for use on skin) , which I wipe/rub over PCB with an old toothbrush. Together with a bit of methylene chloride, tissue takes on all dirt quickly and easily.

 

[JohnRoberts]

MEK is nasty stuff IIRC it can melt plastic parts. (ketone not chloride just saying...look out for mek).

Isopropyl alcohol is pretty benign, vacuum instead of high pressure blowing is also gentler.

JR

 

[rock soderstrom]

I agree with most here. One should approach the matter rather gently. I myself usually use isopropanol and small brushes.

But there is another way, here is a guy who cleans his dirty vintage receiver with the water pressure washer.

 

[aazaa]

Amazing, ... so funny!

 

[Newmarket]

Ultrasonic preferred here if it'll fit in the batth / basket.
If not IPA / brush.
Compressed air for 'kdusty' interiors of equipment but that's not pcbs unless they are in situ.

 

[Script]

MEK is nasty stuff IIRC it can melt plastic parts. (ketone not chloride just saying...look out for mek).

MEK ketone ( C4H8O or CH3CH3COCH2CH3) and methylene chloride ( CH 2 Cl 2) don't look like the same thing. Doesn't necessarily make the latter in any way less unhealthy though. For use in hard cases.

(Just water and soap, have done that too. Worked but really depends on components and what is to be removed -- like sugared coffee or coke).

 

[vintageampfixer]

guy who cleans his dirty vintage receiver with the water pressure washer.

I suppose if I didn't care whether it worked afterwards, I could give it a try!

 

[scott2000]

 

[HP200CD]

I also use IPA and a brush, as mentioned above, but I use the 99% IPA instead of the more readily available 70% variety because (IMHO) it leaves less residue and dries faster.

 

[Script]

Bought Chipquick solder for SMD work recently. On the roll it says 'No-clean water-washable'. Does that literally mean it can be washed off with just water ?