do smelly capacitors release goo that condenses on stuff and effects things? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: September 23, 2019, 12:52:41 am
content: When you repair equipment that has shady capacitors that smell bad, and you replace them and clean the area around them, did you ever noticed effects from contamination?Like it looks really clean, it leaked maybe 100 microliters or less of substance on the PCB near a power rail from a fatty 22000uF capacitor (hardly visible to naked eye but smelled like rotten dog shit). But, does this mean the entire meter has to be cleaned? It started to smell and was quickly turned off and maybe only powered on for like 4 minutes while smelling. I assume the capacitor broke then and there, and was not quietly shitting in the corner over the years because there was no smell. Or perhaps it was slowly gassing but not being heated enough to smell until the capacitor got to a critical point (does this stuff decompose with temperature)?It is a LCR meter with a 1uA test current option, which is a bit noisy, but expected from the poor fixturing and lack of guarding. Don't know if I am chasing a stability ghost here. I can't take this thing apart easily and its just a over all pain in the ass and I feel crazy cleaning it because it looks nice??I assume it won't be stable on the 10 microohm mark regardless of how clean it is unless you do a legit fixture and not 4 alligator clips on a bus bar. with 10 foot long probes.Is a visual inspection with tilting to bright light enough to detect fouling? Can this stuff dissolve in contact flush (the good high pressure ones) (so I can just tilt the instrument over a garbage can and hose it down from above)? Or do I need scrubbing, ultrasonic, etc?do capacitor electrolytes absorb in plastic and effect say temperature stability by messing with the material properties of expansion?It was smelling after being powered on for a while, I don't know if that means it was increasing in pressure and venting already smelly stuff, or if it was breached and just venting stuff that smells at temperature. I threw out the capacitors already.

author: TiN
author_rank: Super Contributor
timestamp: September 23, 2019, 01:33:55 am
content: Good electronics does not smell. That's a rule of thumb

author: coppercone2
author_rank: Super Contributor
timestamp: September 23, 2019, 02:06:04 am
content: how far would you go cleaning that PCB, would it be a scrub in the area of discoloration or would you bathe the entire internals and chassis?I know in a PSU you can be pretty bootleg about it, but this is a capacitor in the AFE. I only see this in equipment like oscilloscope and function generators before, never a sensitive ESR meter.

author: Zero999
author_rank: Super Contributor
timestamp: September 24, 2019, 03:04:24 pm
content: Well I do recall some old phenoic paper PCBs smelling weird, even though the capacitors were all good. I think it was due to the chemicals used to make the boards.Anything which gets hot and releases smoke will smell really bad and can leave nasty sticky substances behind. It's due to pyrolysis which occurs when organic matter is heated to a high temperature, without complete combustion. It releases all sorts of nasty, toxic, carcinogenic substances such as: tar, benzine and carbon monoxide. Some of these chemicals are found in burnt food, which is why BBQ meat and burnt toast increases one's risk of cancer slightly.

author: coppercone2
author_rank: Super Contributor
timestamp: September 24, 2019, 10:23:18 pm
content: those chemicals wont effect high z paths thoughbenzene is a normal product of combustion and has a high vapor pressure I think it would evaporate fast once cleaned off (within a month)what is the amine smell from?

author: FreddieChopin
author_rank: Regular Contributor
timestamp: September 24, 2019, 10:35:32 pm
content: Quote from: Zero999 on September 24, 2019, 03:04:24 pmI think it's good to die of cancer at age of 50 or 60 because social security (ZUS) will be a complete joke in next 15-30 years. Simply it's a financial pyramid and there will be no pensions paid.