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grhughes 28th February 2009 03:50 PM

Ultrasonic Cleaning??????
Is anyone here an expert with ultrasonic cleaning? Tektronix used to be able to dip an entire oscilloscope or modules and completely clean a unit. What does it do to diodes and transistors? What about cleaning ELCO bakelite tube sockets? Thanks

Conrad Hoffman 28th February 2009 05:40 PM

No expert here, but unless you're using a high power industrial unit, it shouldn't hurt anything. The problem is getting water where you can't get it out. I'd never dip an entire scope or plug-in because if water got in the pots, you'd never get it out. Typically the bodies on the old AB pots were sealed with coating of shellac or something, but not the shafts. Careful spraying down and compressed air drying is pretty common. A toothbrush is useful. I can't see any problem with sockets as long as you remove the tubes. A standard test for ultrasonic cleaners is to dip a piece of common aluminum foil in. After a minute it should be wrinkled and perforated- you'll see light right through it! That should give you a good idea of what not to put in an ultrasonic cleaner.

SY 28th February 2009 05:46 PM

If memory serves, the Tek stuff was ultrasonic cleaned in now-banned solvents, not water. Very easy to dry that way and better for the components.

grhughes 28th February 2009 07:11 PM

So if I were to clean a double sided circuit board....
ground planed, plated through hole with transistors, zener diodes, diodes and all epoxy dipped components (ie capacitors, resistors) then it shouldn't hurt anything??? The foil won't separate from the fiberglass?? I should worry about rubber plugged electrolytic capacitors like nichicon 105 degree radials-or axials???? The only pot is a 15 turn Bourns. What would it do to Berrylium oxide paste on the power transistors? Thanks so much! Ray

m6tt 28th February 2009 07:16 PM

I'm not sure if you can use ultrasonics with an alcohol (like isopropyl, ethyl), but we threw whole computer motherboards, power supplies, etc. into that stuff. Somewhere I've seen pictures of laptops running (sans hard drive) immersed in it! As long as it's above 90%, it shouldn't produce much more water damage than a humid day.

boywonder 28th February 2009 07:17 PM

Sounds like you are thinking of a freon degreaser, those things were cool, but have now probably gone the way of the buggy whip.

We had those in the 80's when I worked in the aerospace industry, and they cleaned nasty looking PCB's in no time, but probably blew a big hole in the ozone layer above the plant where I worked.:D

I recently cleaned the pots from my Hickok tester in a small ultrasonic cleaner using simple green, it worked great, just don't leave the item in the cleaner too long.....and rinse and dry well.

grhughes 28th February 2009 09:33 PM

No! No freon TF! What solvent to use? I'm not trying to get the EPA mad at me.
just trying to clean 6 circuit boards on 6 amps that have been stored and gotten dirty and dusty. I have to replace the electrolytic caps as they are now 30 years old. They just power sub woofers. What would be a good, quick drying, legal solvent?Thanks

refference 1st March 2009 01:49 AM

Re: Ultrasonic Cleaning??????

Originally posted by grhughes
Is anyone here an expert with ultrasonic cleaning?
Hi grhughes ,

I have a lot of experience cleaning electronics stuff ,
since I do any restoration , repair and up-grade as my
normal job.

My advices for you are the following :

1) It’s a very good practice to clean PC boards , mainly
if they are made of glass fiber , because if they are dirty , dusty
and mildewed or musty , it will create leakage paths , and
you will hear a lot of “pops” , “cracks” and others exoteric
noises .

2) Regarding the case , I usually do one / two of the actions below :

a) Fill a glass pan ( may be a Pyrex one ) with isopropylic alcohol
( NEVER USE ETHYLIC alcohol ) , and then take the PCB into
the alcohol . Wait for while and then wash carefully with a soft
brush ( may be a common paint brush or even an old tooth
brush ) , in all directions , all components and both sides . If
necessary ( in the case of a very dirty PCB ) , change the
alcohol , and restart all the process . After all done and
cleaned , take off the PCB from the alcohol and dry it ( VERY
WELL ) with a hair dryer .
NO FEAR , because the hair dryer temperature will not cause
any damage to the board and / or to the parts ) .

b) In the case of a VERY , VERY dirty PCB , BEFORE the step
above mentioned , I pulverize it , with the isopropanol
through a painting air pistol , calibrated at 120 psi of
air preassure , and then go to the step a)

OBS. : Do not worry about electrolytics , or ANY other parts
( EXCEPT power or output transformers ) because the
isopropanol does not “ attack “ them in any way , NOT
even the serigraph marks on the components .

IMHO , you must forget about ultrasonic cleaner , because this is
an industrial process , and you have to know the exact rate of
POWER ( of ultrasonic waves ) , the exact BAND of FREQUENCY ,
the proper LIQUID CLEANER ( or SOLVENT )and the TIME of wash ,
or in other way , you can ( .... and certainly will ) cause damages to the PCB and / or the parts , due mainly to the cavitation phenomena .

Regards ,


grhughes 2nd March 2009 03:00 PM

Thanks Carlos!
Very good advice! What kind of air pistol (brand) do you use? Thank you. Ray

AuroraB 2nd March 2009 04:31 PM

FWIW - I once read about a guy who stuffed the whole guitar amp chassis in the dish washer!
I have tried it several times with dirty boards, and it actually works very good!
Obviously there are some components like transformers etc. that are unsuitable for this process and needs to be removed first. Just let the process work, and leave to dry properly before use!
Water and detergent usually don't harm anything that's not powered!

EDIT: I don't think i'd put my scope in there, though......

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