To clean or not to clean?

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msknight
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To clean or not to clean?

Post by msknight »

A question which has always puzzled me is whether to clean a dirty, but functioning motherboard that has come out of someone's attic or garage. The basis of this is the potential to cause more harm by cleaning.

What are people's opinions and if you opt to clean, how do you do it? I'm looking for techniques that don't involve owning specialist tanks or the like (I only have a walk-in shower these days!)
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Re: To clean or not to clean?

Post by gfoot »

I just use IPA and cotton buds for most of it, which is harmless I think? I don't get into all the nooks and crannies, just focus on the tops of the ICs and the areas of PCB that are large enough to get a cotton bud into.
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Re: To clean or not to clean?

Post by Lardo Boffin »

I used an anti static brush set and IPA. Very carefully and for quite a long time!

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msknight
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Re: To clean or not to clean?

Post by msknight »

Thanks folks. Good advice. I've got a set of anti-static brushes on my wish list and my birthday is next month so who knows...

I also have a CompuClean blower so I think I'll use that first, then the brushes, and then IPA to get some of the more stubborn off especially where there are tracks that could potentially harbour rust as there seem to be a number of such holes here and there and I've spotted some on the second hand BBC's that have been in people's attics and garages for any number of years.
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Re: To clean or not to clean?

Post by daveejhitchins »

I'm still of the opinion that using a dishwasher is a good way of cleaning old PCBs! Just remove all socketed parts and remove the lid of any modulator fitted. After using this method for over ten years and not ever damaging any working boards (or causing any knowable damage to non working boards) I can highly recommend it.

Half an hour in an oven at around 50/60 deg C or leaving in a warm place for several days will dry them OK.

In hard water areas - just rinse off with boiling deionised water.

Dave H.
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Re: To clean or not to clean?

Post by msknight »

I'm from the dark ages... I don't have a dishwasher :-)
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Re: To clean or not to clean?

Post by 1024MAK »

Small amounts of household dust in itself is not a problem. However if it gets wet or damp (from the moisture in the air and condensation due to thermal hot/cold cycles), then corrosion of some metal parts is more likely.

Damp or wet dust can also affect the electrical operation, as it results in electrical leakage currents flowing, which can upset sensitive circuits (such as the analogue audio, cassette tape system, reset circuit and analogue/joystick port).

Thick layers of dust reduce how quickly hot running components can dissipate heat to the air, and where fans are used, clog them up, or the air ways / vents.

No doubt Dave H. will pop up and tell you he uses a domestic dish washer. I do mean to try this one day if I ever have a dirty board. Edit, he’s got in before me again! :lol:

You don’t have to use IPA to clean general dust and dirt off. You can use plain tap water or distilled or demineralised water.
First remove all plug in connectors and components, such as chips in sockets, jumper shunts/links/headers etc.
Check that there are no components that use paper or cardboard such as loud speakers. If there are, disconnect and remove them. Also remove the lid of the modulator.

Now wash with tap water. It’s best to use a small jug or small watering can. Don’t wash under a tap that operates at mains water pressure levels. If some of the dirt is oily or greasy, use a little washing up liquid and brush gently with a small paint brush.

If you use soap/washing up liquid, make sure you rinse it off.

If you live in a soft water area where no extra chemicals are added to the water, now skip forward to the drying section.

Otherwise, if you live in a hard water area, or chemicals are added to the water, you need to do a final rinse using distilled or demineralised water.

To dry the board, I recommend placing it at an angle (60 degrees say) in a warm, dry place, such as an airing cupboard or above a hot radiator. Or you could put it in a suitable oven (use the fan setting if applicable). But use a low heat setting.

Apart from the oven (which will obviously be quicker), leave for at least 24 hours for all the water and moisture to evaporate, so that it is fully dry.

Now carefully visually inspect the board and all components for any damage. If everything looks good, refit any removed components and power up and test.

If there is still sticky dirt, clean with IPA and a toothbrush (but not the one you use to clean your teeth).

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Re: To clean or not to clean?

Post by marcelaj1 »

msknight wrote:
Wed Sep 15, 2021 8:20 am
I'm from the dark ages... I don't have a dishwasher
I was thinking about this a while ago and maybe the answer is not so much the machine but the process.

Perhaps having a bowl big enough for the board, something cheap like
https://www.amazon.co.uk/Plastic-Drip-T ... B0051OEDMQ

Then replicate the dishwasher i.e. hot water, water softening salt, detergent tablet- then, after a soak, gentle scrubbing with a selection of brushes/paintbrushes for all those nooks and crannies, followed by rinsing then pop it in the oven for a bit.

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Re: To clean or not to clean?

Post by Ronin47 »

My preference is to clean enough to remove any build ups of dust, and remove any dust bunnies to prevent moisture gathering and allowing for better thermals, in other words I remove the blanket :)

My favoured method is IPA and an anti-static brush, I just can't bring myself to use the dishwasher.
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Re: To clean or not to clean?

Post by 1024MAK »

marcelaj1 wrote:
Wed Sep 15, 2021 8:50 am
water softening salt
Be very careful with salt. If any salt deposits are left behind, it can cause worse problems than dust. Salt attracts moisture, and then results in corrosion.

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Re: To clean or not to clean?

Post by marcelaj1 »

1024MAK wrote:
Wed Sep 15, 2021 9:56 am
Be very careful with salt.
Good point, I should have qualified with "dishwasher salt".

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Re: To clean or not to clean?

Post by danielj »

Dishwasher salt actually charges an ion exchange resin in the dishwasher. Unless you're adding the resin to your washing bowl it'll do naught!

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Re: To clean or not to clean?

Post by marcelaj1 »

danielj wrote:
Wed Sep 15, 2021 3:06 pm
Dishwasher salt actually charges an ion exchange resin in the dishwasher
Arrrg apart from distilled water, trying to think of a non machine method of cleaning a board without leaving a residue on it.

Is there a cheap(ish) cleaning product that will fit the bill,I have a board that is very dirty, but works, haven't the nerve to put it in the dishwasher, perhaps I should flog it as is and leave it to the new owner :?:
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Re: To clean or not to clean?

Post by Wheel_nut »

In the '50s, Carbon Tetrachloride was commnly used in the Industry but it was considered to be carcenogenic if inhaled with Tobacco smoke so it was replaced with Freon ... and then someone found a hole in the Ozone Layer ... so the industry turned to Water based Flux and de-ionised water washing which polluted the water table and turned industrial cities like Endicott NY into wasteland.

I use IPA to remove any Rosin Cored Solder Flux residue and then a good wash (if necessary) with very dilute Washing-up detergent, I find that Aldi's own brand produces less suds than Fairy and I have even used a few drops in a dishwasher instead of a Tablet as a final wash. Dishwasher Tablets are very Caustic and I prefer not to use them.

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Re: To clean or not to clean?

Post by danielj »

marcelaj1 wrote:
Wed Sep 15, 2021 9:58 pm
Arrrg apart from distilled water, trying to think of a non machine method of cleaning a board without leaving a residue on it.
Just wash it with water/mild detergent as Wheel_nut said, agitate with an antistatic brush if appropriate, and give it a final rinse with distilled water. Slosh a bit of IPA over the top to speed drying if you fancy and you're done.

d.
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Re: To clean or not to clean?

Post by msknight »

Looks like a trip to Liddl is in my near future then. We don't have an Aldi round 'ere.
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Re: To clean or not to clean?

Post by Wheel_nut »

msknight wrote:
Thu Sep 16, 2021 10:21 am
Looks like a trip to Liddl is in my near future then. We don't have an Aldi round 'ere.
If you're NOT using a Dishwasher, any washing up detergent will do. I suggested Aldi detergent because a dishwasher will fill with bubbles if you use more than a few drops of Fairy Liquid.

If you are brushing it WET, any brush will do as static charge is not a problem when wet.

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Re: To clean or not to clean?

Post by marcelaj1 »

danielj wrote:
Thu Sep 16, 2021 9:53 am
Slosh a bit of IPA over the top to speed drying if you fancy and you're done.
Not sure I'll be sober after that :?

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Re: To clean or not to clean?

Post by system11 »

daveejhitchins wrote:
Wed Sep 15, 2021 8:13 am
I'm still of the opinion that using a dishwasher is a good way of cleaning old PCBs! Just remove all socketed parts and remove the lid of any modulator fitted. After using this method for over ten years and not ever damaging any working boards (or causing any knowable damage to non working boards) I can highly recommend it.

Half an hour in an oven at around 50/60 deg C or leaving in a warm place for several days will dry them OK.

In hard water areas - just rinse off with boiling deionised water.

Dave H.
I had an ebay customer destroy a Flying Shark arcade PCB doing this. It turned into quite a dispute until he finally admitted that it had worked but stopped working after being dishwashed. Quite aside from anything it will accelerate degradation of the pin plating on the chips because the water is full of salt. If you really must wash them, gently in soapy water, but it should be a last resort - I've only done it a couple of times for PCBs which were covered in mold spores far beyond 'cotton buds and alcohol' resolution.
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Re: To clean or not to clean?

Post by 1024MAK »

IPA / alcohol is not always very effective at removing water soluble dirt.

Various alloys have been used for IC / chip, socket contacts and connector pins/receptacles. Both for the base metal and for any plating. If the chip pin alloy includes silver, the pins may tarnish over time anyway.

Soft tap water / demineralised / deionised water is perfectly fine for washing PCBs and components. As long as any detergent is properly washed off. And it is allowed to completely dry before being powered up.

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Re: To clean or not to clean?

Post by msknight »

Just to let you know that I'm still here... watching... learning... - I didn't just ask the question and run...
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