Circuit boards - cleaning?

hindsight · Posted: Sat Oct 10, 2009 4:05 pm Post Subject: Circuit boards - cleaning?

Hi all,

I had a go at cleaning my old 70's tuner-amplifier which had become clogged with dust through the years. It all went well up to a point - I used an air cannister to get most of the dirt off the circuits and pots and connectors and so on. But then I decided to lightly clean the main circuit board with isopropyl alcohol. After doing this the board was left covered in large cloudy white marks once the alcohol had dried out. I bitterly regret this now, and am worried about plugging it back in, in case it blows or just fails to work.

Do you think the white marks left by the alcohol cleaning might have destroyed the board?

Is there any other substance I can use to clean off these white marks?

I have used isopropyl alcohol on boards before without any adverse effects, but these were in modern appliances. I'm worried these older appliances have to be handled differently. This is a vintage amplifier which I had shipped to me from Germany some years back - it's an item I love dearly and would appreciate any advice as I don't want to lose it.

mattylad · Posted: Sat Oct 10, 2009 8:52 pm Post Subject:

This should be able to clean it for you.

I have never found ISO to cause any problems with pcb's, new or old.
Plastic yes - not the stuff your old board will be made off.

It should just wi[e/brush away now.

ericmark · Posted: Sat Oct 10, 2009 10:52 pm Post Subject:

I have also seen what appears to be a white powder and I realised it was always there but the oily coating had disguised it. And I found once cleaned this coating seemed to be hygroscopic so I sprayed with WD40 this seemed to work OK.

Not sure what the coating is I had assumed just dust that had set like concrete.

hindsight · Posted: Sun Oct 11, 2009 1:27 pm Post Subject:

Thanks for your replies. I could swear that this board looks and feels like wood that is coated with plastic. I have used ISO on many modern appliances and never had a problem so maybe it's just that particular mix.

I'll take a walk over to Maplins tomorrow. The only problem is that, if I go there, it's one of those places where I end up spending a fortune - just so much great stuff.

Thanks again, I'll report back to let you know how it goes.

electronicsuk · Posted: Sun Oct 11, 2009 8:13 pm Post Subject:

In my experience the best PCB cleaner is good old soapy water, although whether or not you would want to try this with an old and delicate board is another matter.

__________________
Matthew

"I told you, I only wrote that poem to test my printer!"

hindsight · Posted: Mon Oct 26, 2009 2:48 pm Post Subject:

Hi, well, I tried the PCB/Flux cleaner and it removed some of the stain, but there was some residual left. I was tempted to try the WD40, but it's a substance I'm a little wary of. So I tried the soap and water and it removed a good deal more. Left it unplugged for a week after that, just to be safe. It's working fine, thankfully and sounds great. Incidentally, I was getting some channel slippage on the tuner before all this - that seems to have stopped now. Happy days.

I have no idea why the alcohol caused this stain, but I won't be using it on any more vintage gear.

Thanks for your help, everyone.