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I am aware water conducts electricity because of its impurities.
However I am not sure if distilled water is pure enough to be safe to use to wash the potentiometers(and electronic boards in general), or should I go for deionized water as its more pure than distilled water.

Why wash them and not use contact cleaner ?
Because I have been gifted this old electronic device and I would like to restore it to its former glory. I am ready to disassemble it fully and clean/remove any dirt I can find, to best of my abilities.

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    \$\begingroup\$ If you wash the potentiometers you will need to re-grease them. I once had a batch of pcbs cleaned during production which had potentiometers on them. They worked fine initially, but once they were in the field they had an extremely high failure rate. \$\endgroup\$
    – Drew
    Feb 28, 2023 at 18:14
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    \$\begingroup\$ and usually, de-ionization is the lower-cost alternative to actual destillation, which tends to lead to purer product. However, the method used doesn't really define the purity achieved: Purified water comes in different grades, which are standardized. You can find de-ionized water that is "purer" in some respect than distilled water, and vice versa. You generally don't need extremely clean water for board cleaning. Generally, as Drew says, some parts are not meant to be washed – and especially in older electronics, you need to assume that's the case for everything, including the PCB. \$\endgroup\$ Feb 28, 2023 at 18:19
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    \$\begingroup\$ Contact cleaner or even WD40 would be better than water, as you want to reduce friction and oxidation \$\endgroup\$
    – Hoagie
    Feb 28, 2023 at 18:36
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    \$\begingroup\$ Why are your choices only between water and water? \$\endgroup\$
    – DKNguyen
    Feb 28, 2023 at 19:16

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When using de-ionized and/or distilled water to clean electronics, as soon as the water is on the dirty board it is no longer clean. Any salts will be readily dissolved and spread. This is a problem with any kind of cleaning. It is a good choice to use for general cleaning. Rinse often and over and over. Be gentle.

The water must all evaporate before applying power. Use a low pressure air flow (squeeze bottle) to force water from nooks and crannies. Heating in an oven at about 70 degrees Celsius for an hour or two. Watch out for plastic parts. You don't want the water to boil. It can cause damage.

Follow with 99% Isopropyl alcohol (not the diluted stuff) Work it with an acid brush. Rinse Rinse Rinse.

I have used WD-40 in the past, but I find that it attracts dust on all the surfaces it is on.

For potentiometers, move the control to one end. Put 99% Isopropyl in a squeeze bottle and spray into the potentiometer. Use an air puffer (squeeze bottle) to dry Do not operate the control. Use a lubricant such as Caig DeOxIt F100L-L25C. This is not a recommendation. Just an example. There are others. This one comes with a precision dispenser to lubricate just the potentiometer. Spray lubrications just get on everything and attract dust.

Once lubricated operate the control to the other end an repeat the process. This should remove any gritty stuff that will scratch the resistor. Once lubricated then operate the control back and forth.

Old potentiometers eventually form a groove where the wiper contact touches the resistor. When the groove wears through the potentiometer must be replaced. When powered on, operating the control back and forth should be quiet. If there is static noise while operating it is either still not clean, or worn through. I have carefully disassembled potentiometers to clean them, but only as a last resort. They are delicate when disassembled so go slowly. When taken apart you can see if the groove is worn through.

If switch contacts are accessible, then a burnishing tool (not a file) can be used to restore the contacts. The contacts are often a thin layer of material to achieve good wetting on closure. Once the layer is worn through the switch should be replaced.

If the contacts are not accessible then cleaning fluid can be dripped in if necessary. Any cleaning fluid must be evaporated out before powering.

If the cabinet is wood or plastic I cannot advise. Enjoy your restoration. Sounds like fun.

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