Cleaning RIFA guts - Page 1
Forum section: electronics / repair

author: BradC
author_rank: Super Contributor
timestamp: March 14, 2021, 11:53:22 am
content: My Tek 2440 scope got RIFAd, and it spilled its guts all over the board.I've alternated between Ethanol, Isopropanol and DI water with gentle scrubbing, but there is still some residue and a particular stench that I can't seem to shake. Does anyone have any magic fluids that are likely to make this job easier and less smelly?

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 14, 2021, 01:10:25 pm
content: Just to make sure that you know what you are looking for:

author: BradC
author_rank: Super Contributor
timestamp: March 14, 2021, 01:50:55 pm
content: Oh this wasn't a "boom". This was a "slow cook". I turned it on to warm up, and then went outside to do other stuff. It certainly "warmed up".The sludge on the board was/is vile, and the smell is pretty noxious. I didn't use gloves to take that pic, and after 3 washes I still can't get the smell off my fingers.A "few" years ago my HP 3457a got "Schaffner'd" and left a stain on the wall and a smell that took a while to dissipate. This was much worse, and as it was 38+ degrees outside the house was closed up with the A/C on. As I was outside when it went, and the fan managed to beautifully purge the smoke into the room which was then circulated throughout the house. The "Wife Approval Factor" (WAF) on my choice of test gear was not high. Moreso when I told her I'd picked up the bits in 2017 to do the 'scope and the pair of HP 3478a meters because we didn't want that "Schaffner" smell again. You can't rush these things.Still, an opportunity to re-cap the PSU and replace the 29 year old DS1230 NVRAMs.

author: Per Hansson
author_rank: Unknown
timestamp: March 14, 2021, 05:08:29 pm
content: I have not had the misfortune of these failing on me so I don't know the usefulness of this recommendation but what about using acetic acid (vinegar) to clean it up?It is a pretty strong acid and takes care of most things in my experience

author: bd139
author_rank: Super Contributor
timestamp: March 14, 2021, 07:42:43 pm
content: The stuff is fairly difficult to get off. I just left it there when I had one blow

author: Gyro
author_rank: Super Contributor
timestamp: March 14, 2021, 08:19:37 pm
content: The dielectric is paper, so I think the mess is burned epoxy residue. I'm not sure how much that helps, but probably explains why it's so hard to clean off.

author: bd139
author_rank: Super Contributor
timestamp: March 14, 2021, 08:25:10 pm
content: Makes sense. It stops stinking after a few days as well which is handy.

author: jdragoset
author_rank: Frequent Contributor
timestamp: March 14, 2021, 09:53:14 pm
content: Try very small test sites with various solvents:Charcoal lighter (distilled kerosene)Coleman fuel (naptha)AcetoneGoof Off (acetone/Xylene)Nitro Benzene (gunpowder solvent)Brake cleaner (various solvent mix)Carburetor cleaner (various solvent mix)When I say small I'm talking about the point of a toothpick.When you find what works, apply it very carefully where it is needed.Follow up with other solvent of the above(if necessary), IPA and DI water rinse and bake dry

author: srb1954
author_rank: Super Contributor
timestamp: March 14, 2021, 11:13:07 pm
content: Quote from: bd139 on March 14, 2021, 08:25:10 pmIn my experience the stench doesn't disappear for at least 2 weeks.

author: BradC
author_rank: Super Contributor
timestamp: March 15, 2021, 03:48:09 am
content: Quote from: srb1954 on March 14, 2021, 11:13:07 pmYeah, it has been over a week and the inside of the scope still stinks. I pulled the PSU the day it happened, so it's just the smoke that has left the residual smell.

author: perieanuo
author_rank: Frequent Contributor
timestamp: March 15, 2021, 11:03:40 am
content: acetone rules, except missing labels afterwards

author: wiesl
author_rank: Contributor
timestamp: March 16, 2021, 02:39:41 pm
content: Thankfully I replaced all RIFAs

author: Haenk
author_rank: Super Contributor
timestamp: March 17, 2021, 01:11:39 pm
content: Rule of thumb: Always open and check for RIFAs before powering older stuff up(Though I have to admit I recently powered up an older calculator with a RIFA in it and didn't bother to replace it due to being sold and the buyer being warned). It wasn't cracked (quite a miracle) and it didn't explode (another miracle) after laying dormant for 40 years or so...)