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lostrego
20th February 2012, 17:34
Hi there, I'm again gathering some information to my A4KD never ending project. ;)

Question is simple, for what we all know here, there is no much danger in putting a mobo on the dish washer or washing it with tap water, but what about a PSU circuit board?

Thats because The one on my A4KD is really infested with all kinds of dust, goo and who kows if even some creatures :lol:.

Before cap changing, wire renewal and all that some cleanup of this item must be done, but again pehaps water is ok for cleaning a 5v/12V DC running circuit letting it dry for 24-48H etc... but for an item that runs on 220V AC and have coils and such I think that we are talking about dangerous things now, even by letting it dry whatever time is necessary.

Bye.

AmiNeo
20th February 2012, 18:14
Personally I'd be opening it up and using compressed air rather than water, unless you fancy discharging and desoldering all the components first.


My 2 pence.

lostrego
20th February 2012, 18:40
Yep I assume that some of the big capacitors rated at 300 or so V must to be discharged before any procedure but for compressed air I actually haven't any air compressor, and dont know if one or morre of those compressed air cans would be enough to do all the cleaning (belive me, it's very dirty inside it).

jvdbossc
20th February 2012, 19:50
Rkauer previously posted that they are mostly discharged by a resistor onboard.

I have been looking at psu designs and noticed in all psu designs have a resistor to get all power off in short time (20 minutes)

But please check before any handling by mesuring the voltage with of course the isolation material in your hands..

---------- Post added at 20:50 ---------- Previous post was at 20:47 ----------

And I think caps are not wather resistant, If I would use it, I would use it that no water can flow inside the caps. I would not stop with wather as last product. Probably it leaves some residu. I would suggest to end with some distilled water and alcohol... Have a drink while you are .. (not from the spiritus of course)

lostrego
20th February 2012, 20:23
Thanks to both AmiNeo and jvdbossc :)

@jvdbossc: Interesting point that of the discharge resistor, I dind't know that. And no matter with the old caps as their destination is the trash bin, they will be all replaced (I've here some nice new Panasonic couterparts just waiting to do the job :)), in fact that's main the point of the cleaning, just to have a clean surface to do all the job.

With water I've experienced various results, I had no problems at all with it and the A4000 mobo but with an X-surf it ended with residue, even using distilled water (the residue was lead oxide as I was told by Rkauer) that I've to clean again with IPA.

Perhaps IPA shoud be the best option here but asked this as It's easier/faster to just take it to the bathtub an do some showering and gentle brushing on it.

AmiNeo
20th February 2012, 20:28
try sticking a straw in the end of a can of compressed air for the tight spaces, one of those really thin red ones...

IPA would be my next choice and maybe some poking with some cotton wool Q-tips but be careful its all evaporated before turning it back on again :lol:

lostrego
20th February 2012, 20:30
And for the drink: Sure, any excuse is valid to have one :lol:

orb85750
20th February 2012, 20:39
but again pehaps water is ok for cleaning a 5v/12V DC running circuit


What?

lostrego
20th February 2012, 21:00
but again pehaps water is ok for cleaning a 5v/12V DC running circuit


What?

That was exactly what I said the first time I've read that it could be done. :lol:

BTW I think that I expressed myself wrong here (by that I meant a circuit that is designed for run at low voltages say without capacitors rated at hundred of volts etc... , I don't want to mean that the circuit was actually running while the cleaning. :lol:).

As you may notice at my avatar, English is not my mother language. :roll:

jvdbossc
20th February 2012, 21:31
IPA is for cleaning labs or medical usage.. Ethanol is close.. I don't think it matters much for our usage, Use wathever is available...

I have a distiller at regulated temperature... Distilled wather does not leave marks...

Usually available in shops.. I have an aquastill it vaporisez anything between 0-200 degrees.. Resulting in distilled wather etc.. etc..

bdb
21st February 2012, 07:56
Sorry guys, it is very bad to use an ionizing solvent on an electric circuit board; water (distiller/deionized/tap) not only conducts electricity, but also is an oxidizing agent.

You want to use a low molecular weight (thin) hydrocarbon solvent (one that is free of oxygen molecules -- no alcohols, ketones, aldehydes, ect.) to clean the board. There are several available. To find one locally, ask a TV/Radio repair shop.

-bdb

lostrego
21st February 2012, 15:44
Sorry guys, it is very bad to use an ionizing solvent on an electric circuit board; water (distiller/deionized/tap) not only conducts electricity, but also is an oxidizing agent.

You want to use a low molecular weight (thin) hydrocarbon solvent (one that is free of oxygen molecules -- no alcohols, ketones, aldehydes, ect.) to clean the board. There are several available. To find one locally, ask a TV/Radio repair shop.

-bdb

Thanks for advice bdb :)

You mean the good old CRC contact cleaner or something alike?

cosmicfrog
21st February 2012, 21:29
nagh give it a good wash, we talking ideal circumstances here
pure water don`t conduct elec anyways so if can use that if no solvent around
but as zetro likes to say good old screen wash is cheap enough and contains exactly what u need
but its not like you be letting the thing dry out via evaporation is it ??

ionizing solvent yay but think u might want look up properties of distilled water again

lostrego
22nd February 2012, 17:31
@cosmicfrog

Well, better I'll decide the best option when I open it, depending of the amount of dust and goo it has I'll go for more or not so drastic options:

1-Light dust - Brush and CRC
2-Average amount of dust - Vacuum cleaner, brush and CRC
3-Heavy amout of dust - Vacuum cleaner - brush and gentle dose of IPA
4-Rat's Nest (sure it will be more like this) - Direct to the bath tub, water, brushing and whatever It needs. :lol:

cosmicfrog
22nd February 2012, 18:55
Brush

weapon of choice, good to have a selection to get into those tight little spots :cool:

rkauer
23rd February 2012, 01:15
For PSU I usually just use a vacuum cleaner and a large enough paint brush.

Water is OK if you let it dry properly for a few days before powering up.

Soaking the board in IPA after water cleaning is good enough, too.

And yes, all AT/ATX power supplies have self-discharging resistors on the mains capacitors. Unneeded on the DC power lines because they discharges themselves to the motherboard after power-off.

bdb
23rd February 2012, 04:56
@cosmicfrog

I'm sorry but water does conduct electricity, pure or otherwise. The oxygen atom in H2O is electron "rich" and the electrons make it not only an "electricity" conductor but also causes oxidation in the presence of metals. Think back to your college chemistry classes.

People are routinely electrocuted by appliances falling in their bath water or standing in water when a live/hot cable is unsheathed (fallen electrical poles). Circuits that are tiny are easily ruined by water; just drop your cell phone in water and see if it works afterward

robinsonb5
23rd February 2012, 09:08
just drop your cell phone in water and see if it works afterward

I have an old cellphone somewhere that's been through the washing machine on a thorough wash cycle. The battery died, but the rest survived and worked fine once it had thoroughly dried out!

bdb
23rd February 2012, 09:58
Well you were lucky the rest of the phone survived; now what about the battery? Did it die because it committed suicide?