Ultrasonic Cleaning

[+dhe]

I've been reading a bit about folks cleaning old retro equipment with ultrasonic cleaners.

 

I've cleaned key caps with this method and was very very happy with the results. I'm hesitant to drop say a power supply board, or cables in water.

 

Anyone know the rules on cleaning old computer boards? How long to dry before putting current through them again?

 

I read commodore used to use dishwashers to clean the flux off their boards! (Dawn or Kascade)? 😃

[wierd_w]

Significantly less time if you blast them with 91% isopropanol first.  That will dry the board VERY fast.  Be advised that this will loosen/detatch any hot glue, and will loosen/detatch/dissolve some board coatings as well. (might be important if the board has hotglue stablized bodge wire, et al.)

 

My ultrasonic cleaning unit is too small for basically anything beyond say, a floppy drive's logic board though, and I have never tried cleaning such a board that way inside it.

[+OLD CS1]

1 hour ago, dhe said:

Anyone know the rules on cleaning old computer boards? How long to dry before putting current through them again?

Get a UC with a heater (even the cheap ones at Harbor Freight have that.)  Use the recommended amount of UC cleaner in the water.  I use distilled water in the tank, and "de-gas" it after adding the cleaner, i.e. run it for about five minutes to "shake out" all the bubbles in the water and help mix the cleaner.  I let mine heat to about 180 degrees Freedom.  Run the cycle depending upon how "dirty" the board is.

 

Rinse in distilled water.  I use a towel then fans for several hours, or some kind of heated forced air to dry.  Watch for water left in hard-to-reach places, under components, &c.  You can rinse with isopropyl alcohol after rinsing if you want, as this will displace water; I get 99% from a medical shop, but I would recommend staying above 90%.  You can get 90-92% in stores.

1 hour ago, dhe said:

I read commodore used to use dishwashers to clean the flux off their boards! (Dawn or Kascade)? 😃

I read that before, too.  Dishwasher detergent can leave residue, especially the "spotless" kind, so you would want to run without detergent OR rising agent.  Also, if the item is particularly dirty, be ready to clean the trap.  (Clean it anyway, you nasty buzzard.)  If you are cleaning circuit boards, I would dry them as quickly as possible to prevent the evaporating water from leaving its impurities (potentially conductive) on the boards.  Some debate on whether to use the dishwasher's heat or not.

 

I have cleaned things like Amiga and Commodore clam-shells in the dishwasher.  I recommend not using any detergent with bleach.

 

YMMV.

[+OLD CS1]

Oh, one more thing to add is that if you are cleaning flux off a board, you may need to add additional cleaner to the solution.  I start with the recommended amount, unless it is obvious that I have globbed on the flux a la Louis Rossmann, then add a little more as-needed.

 

My UC is only about 2/3 gallon.  What I wind up doing for some things is cleaning them in sections.

[CC Clarke]

The majority of the flux you'll find on a 4A motherboard is from factory hand-soldered repairs made after the PCB was flow-soldered.  Dust accumulating around hot components is a bigger issue than leftover flux residue.  Heat is a computer's mortal enemy.

 

There are two main sources of grime that afflict 4A's: The GROM and I/O ports.  The GROM port needs to have the 90 adapter removed, the black clip removed and the remnants of the oil-impregnated pad removed.  The adapter should be immersed in 91% IPA and cleaned with a stiff nylone brush, and rinsed thoroughly before drying.  If you have an ultrasonic cleaner, so much the better.  The female port on the motherboard can be cleaned with IPA then dried with compressed air.

 

All male edge connectors (this includes the I/O Port) can be cleaned with a pencil eraser.  Do NOT flow solder onto any worn or scratched pads; solder is too soft for repeated mating/de-mating.

 

CC  

Edited November 23, 2022 by CC Clarke

[Tursi]

I've cleaned a number of boards in the dishwasher. Only boards I didn't mind losing, but they all came out lovely and they all worked. Done arcade boards, a 2600, and even did a modern PC (I was given one to fix that came from a heavy smoker's home...)

 

Coils and similar parts with internal cavities are the biggest risk. Remove all batteries and discharge caps before you start. It must be FULLY dry before you power it up - I would usually give it at least 3 days and a visual inspection. And keep in mind that you may well destroy it anyway. But everything I've run through came out fine and very clean.

 

[matthew180]

All the things Tursi mentioned.  For coin-op arcade boards, especially the CRT monitor PCBs, the dishwasher is very common.  Put the board in the sun (indoors or outdoors depending on your local) to dry for a few days.  Parts will absorb moisture, so you have to wait for them to dry out.  Putting them in an oven at low temp (around 100c) also works.  You can find IC drying guides online.

 

I don't think there are any parts on a 99/4A motherboard that cannot be washed...  maybe.  Actually, thinking about it, I'm not sure about the white power distribution strips used on the 99/4A.  Depends on what the layers are made of, and how well they are sealed.  Personally I would experiment on a broken one first.

 

Re: ultrasonic cleaners.  Work fine.  I have one with a heater and I use a cleaner solution specifically for electronics components (Branson EC Cleaner).  The problem with ultrasonic cleaners is, getting one large enough for a 99/4A motherboard is going to be expensive.  I think I paid around $400 for mine, stainless steel with heater and timer, and it is about 10x8x6 (inches); so not big enough for most retro computer motherboards.

 

99% isopropyl alcohol (MG Chemicals 824) and Q-tips work great and are probably the fastest and cheapest option.  You can remove a lot of gunk this way, and have low risk of damaging anything (just be gentle).

[+5-11under]

Additional notes:

Watch out for mechanical parts such as switches, etc. They might not be able to handle water.

100C could be too hot for some plastics. I'd stick to 70C or so to be safe.

[Tursi]

4 hours ago, 5-11under said:

Additional notes:

Watch out for mechanical parts such as switches, etc. They might not be able to handle water.

100C could be too hot for some plastics. I'd stick to 70C or so to be safe.

Good call. I expected the 2600's switches to be destroyed, but they were so badly seized when I put it in that I had nothing to lose. They actually worked when they came out!

Of course, 2600's switches are open on both ends so drain nicely

[+dhe]

I've been slowly getting an ancient Amiga A500 back on it's feet.

The tank mouse was grody to the max, and it's feet had dissenter-grated.

 

I went with this unit:

 

I'd tried to clean it by hand with toothpicks and q-tips but only got so far....

 

I ran the plastic parts through at 95 degrees for 20 minutes and they came out squeaky clean.

 

Once you mention to the finance department what a great job it does on jewelry, approval is usually swift. 😃