Black Smoke? - Page 1
Forum section: electronics / general

author: THATguy
author_rank: Regular Contributor
timestamp: January 26, 2018, 10:04:47 pm
content: 1990's Sunbeam food processor, began to smoke, then went BANG!There was some slight food jamming on the ends of fibrous vegetable leaves, no stalling though.Decided to scrap it, quite yucky inside!I think it's fibreglass from the motor belt. Would hate to breathe that in! It has a heat vent on the base too!Perhaps it was repairable? Or did the blowout damage other components?Not really worth it, I guess.I wonder if the capacitor died due to age, or the overwork due to jamming?

author: helius
author_rank: Super Contributor
timestamp: January 26, 2018, 10:18:14 pm
content: Quote from: THATguy on January 26, 2018, 10:04:47 pmThose mylar capacitors (frequently branded RIFA) have a built-in automatic destruction mechanism. Over time the plastic encapsulation cracks and lets moisture into the foil which then swells until it bursts apart.Nothing else will be damaged as a result, in fact the equipment usually still operates but with greatly increased conducted EMI.

author: hermit
author_rank: Frequent Contributor
timestamp: January 26, 2018, 10:55:03 pm
content: I didn't realize they were electing a new pope?

author: THATguy
author_rank: Regular Contributor
timestamp: January 27, 2018, 08:37:08 am
content: After it began to smoke, I stopped it and cleared the vegetables.After that it ran, but only on full speed, no matter which speed button I pressed, then there was the explosion.I fixed that first picture, sorry about that.

author: bd139
author_rank: Super Contributor
timestamp: January 27, 2018, 09:45:14 am
content: Welcome to the RIFA X2 victim club. I thought it would be one of them when I saw the thread title.At least it didn’t fizzle and spray gunk everywhere. That’s usually what happens and that stuff is impossible to get rid of.

author: dexters_lab
author_rank: Unknown
timestamp: January 27, 2018, 10:36:36 am
content: those RIFA caps! i can't imagine how many old electrical things have gone bang because of them!i've had a couple go pop on me

author: SeanB
author_rank: Super Contributor
timestamp: January 27, 2018, 02:08:05 pm
content: Funny enough was at the scrap yard today, and there was in the pile a large control panel for some piece of equipment, with a lot of single turn pots on the one panel, and some nice CK switches on there, with the switches having on the back a snubber of a resistor ( did not read the value, they were all rather faded) and a RIFA clear case capacitor on each. All of the capacitors were crazed, and a good number had nice burn marks in the cases where they had arced through as well. Not sure what it had controlled, but there was also in the case a Samsung AWE series controller board, so I guess in that machine they had a big need for cooling, and decided the easy way was to take a standard split unit and use the refrigeration circuits in there. Lot of LENZE made transformers there as well, and a nice little hour meter which I took, with permission of the yard manager. I also got some stainless steel heavy gauge mesh, to use in the BBQ as a grid.

author: kony
author_rank: Regular Contributor
timestamp: January 27, 2018, 03:39:06 pm
content: Yuck, those RIFA filter caps are terrible! I replace those transparent ones on sight, without thinking twice - seen too many spewing its guts out. Worst thing being there are omnipresent even in otherwise very good quality equipment.

author: bd139
author_rank: Super Contributor
timestamp: January 27, 2018, 06:38:00 pm
content: Incidentally I bought some new ones to refit the dodgy looking one in my HP power supply and they are a different colour now. A sort of transparent grey. Hopefully that means there has been some re-engineering!

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 27, 2018, 06:58:25 pm
content: Great, I just realized my food processor could have the same shitty caps in it. It's a Braun from the same era.

author: bd139
author_rank: Super Contributor
timestamp: January 27, 2018, 07:24:27 pm
content: Numatic Henry vacuum cleaners have them in here. They're in a lot of stuff.Comedy timing for an explosion of one here:

author: THATguy
author_rank: Regular Contributor
timestamp: January 31, 2018, 04:01:44 pm
content: HAHAHAExactly the same smoke as mine.I just noticed, also that mine blew a large resistor.

author: Wolfram
author_rank: Frequent Contributor
timestamp: January 31, 2018, 05:29:06 pm
content: Quote from: helius on January 26, 2018, 10:18:14 pmThis looks very much like a Rifa PME-271. These capacitors are not mylar but zinc-paper. The epoxy cracks over time and allows moisture to absorb into the paper. This leads to increased leakage current and eventually catastrophic failure.

author: Mark
author_rank: Frequent Contributor
timestamp: January 31, 2018, 05:33:54 pm
content: Same happened to me in an old surge generator, it took ages for the smell to leave the room. I replaced them with the same RIFA caps purchased new from RS or Farnell... always have second thoughts, so I am wondering if Rifa solved the problem of the cases cracking or if I should rip them out again.

author: bd139
author_rank: Super Contributor
timestamp: January 31, 2018, 06:18:18 pm
content: I replaced with the same caps too. The new ones look grey instead of yellow so hopefully they fixed that issue.Really mains filters (Schaffner!) and any X/Y class caps should be replaced every 10 years I think. I’ve never seen one newer than about 15 years blow up.