Tips for deep cleaning a crusty old logic board?

decryption

New Tinkerer
I finally cracked open my SE/30 and found that it is filthy inside, with rat droppings everywhere :(

se30_01.jpg


The good news is that the 1989 battery hasn't leaked! But a few capacitors have begun to leak, but not too severely. Hopefully I got to it in time. Here's what the board looks like after a very basic clean and removing the RAM & ROM:

se30_07.jpg


Underneath looks good.

se30-logicboard-back.jpg


I have a friend that can do the recapping process (what a nice guy!) but I want to give him a spotless logic board before he works on it - does anyone have any tips on how to do a deep clean of the board without ruining it?

I've done a bit of research and I think I will approach it like this:

  1. Blow off all the dust I can with some compressed air and a non-static brush.
  2. Get some sort of degreaser, mix it with 99% isopropyl alcohol and spray it on the board to loosen up any crap (let sit for 15-30min)
  3. Rinse off the crap and degreased in a tub of demineralised water (let sit for 15 min)
  4. Place in a another tub of 99% isopropyl alcohol to displace the water for 15 min
  5. Get the hairdryer out along with a soft anti-static brush (any ideas for a good brush to use? I have a few paint brushes but I'm worried they'll generate static) to blow dry the board.
Am I over thinking this, is there an easier way to get it looking spotless and not damage the board?

What's a good degreaser to use? Is a basic dishwashing liquid okay or should I use something else like an electrical contact cleaner instead? (e.g: this from a local auto store)

Or should I just get access to/buy a big ultrasonic cleaner so it gets any acid from the leaked caps that may have gone under or between the legs of an IC?
 

This Does Not Compute

Administrator
Staff member
Oct 27, 2021
331
478
63
www.youtube.com
I've had good luck cleaning PCBs by just soaking/scrubbing them in 99% IPA. I'd avoid a degreaser or other harsh chemical, but there are a number of PCB cleaning solutions (that you usually dilute with distilled water) that can help move stubborn dirt. These are most commonly used with an ultrasonic cleaner, and if you're concerned about leaked electrolyte under chips, that's the best way to go. Maybe there's a hackerspace/makerspace near you that has a sufficiently-sized ultrasonic cleaner you can use?
 
  • Like
Reactions: JDW and decryption

decryption

New Tinkerer
I've had good luck cleaning PCBs by just soaking/scrubbing them in 99% IPA. I'd avoid a degreaser or other harsh chemical, but there are a number of PCB cleaning solutions (that you usually dilute with distilled water) that can help move stubborn dirt. These are most commonly used with an ultrasonic cleaner, and if you're concerned about leaked electrolyte under chips, that's the best way to go. Maybe there's a hackerspace/makerspace near you that has a sufficiently-sized ultrasonic cleaner you can use?

Thanks for the input!

A nice person on Mastodon that lives not too far away has a nice big ultrasonic cleaner the entire board will fit in, so that's an option.

I'm thinking about trying the 99% IPA in a tub with a gentle scrub with an extra soft toothbrush first - no degreaser like you said - first and seeing how that goes, as it's pretty easy and the board isn't _that_ dirty. Then if I don't get good results with the IPA alone, I'll get some of this PCB cleaning solution and try it in an ultrasonic cleaner with demineralised water.
 

decryption

New Tinkerer
For anyone following (possibly nobody!) I managed to clean the board without an ultrasonic cleaner.

Before:

se30_logic_before.jpg


After:

se30_logic_after.jpg


Here's some high-res pics if the forum software resizes them:


Here's the steps I took if anyone is interested:

Poured 5L of demineralised water into a tub, along with about a teaspoon of basic dishwashing liquid. Gave it a shake to bubble up, then dipped the board in. Let it soak for 30 min.

Took the board out, gave it a shake on a towel, then put it in back in the tub and gave the board a gentle scrubbing with an extra-soft kid's toothbrush. This dislodged a lot of the crap on the board the detergent loosened up.

After scrubbing, took the board out and rinsed it off with another 5L of demineralised water.

Patted the board dry, gave it a good shake, then blew out as much water as I could with a hair dryer.

Now I have it resting on a towel to dry out. Will post it at different angles for a few days before handing it off to a friend to do the recapping process.