rifa electrolytic Axial capacitors safe to use or replace - Page 1
Forum section: electronics / repair

author: pcmad
author_rank: Regular Contributor
timestamp: August 22, 2019, 02:19:28 am
content: arerifa electrolytic Axial capacitorssafe to keep or replacefound in a scope and the rifa cap looks ok and i dont want to replace it if i dont have toadvise pleasethank you in advance

author: rsjsouza
author_rank: Super Contributor
timestamp: August 22, 2019, 02:40:35 am
content: Rifa electrolytic capacitors are similar to any other - nothing particularly bad or good.The troublesome Rifas were the polyester class X (X1, X2) that blew or caught themselves on fire due to bad materials employed in its construction.Google for "rifa capacitor failure" and you will see many examples. There is even an EEVBlog episode:

author: Psi
author_rank: Super Contributor
timestamp: August 22, 2019, 02:57:14 am
content: I don't want to mess with no RIFA addicts.

author: wraper
author_rank: Unknown
timestamp: August 22, 2019, 03:11:53 am
content: Quote from: rsjsouza on August 22, 2019, 02:40:35 amThey are metallized paper, not polyester. And they are not limited to safety capacitors. They blow up due to moisture absorption, usually after staying not powered for significant time.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 22, 2019, 03:26:07 am
content: Electrolytic? Axial?If they're normal electrolytics then replace them if the ESR is rising (if you have an ESR meter to test), or if over, say, 20-30 years old, or obvious signs of bloating/leaking.Tim

author: tkamiya
author_rank: Super Contributor
timestamp: August 22, 2019, 03:27:09 am
content: In my case, I would only replace them if I notice damage or stress in individual pieces. Otherwise, I'd leave them in.In my older gear, everything is 30 to 40 years old. Everything is well past designed life. Everything has chance of failure already, today, tomorrow, or a year later. Or, it might live for few more years. When I get something new, I open it up and closely visually inspect. Cracks, leaks, bulges will be noted. Replace as necessary.

author: Kjelt
author_rank: Super Contributor
timestamp: August 22, 2019, 07:16:54 am
content: Quote from: tkamiya on August 22, 2019, 03:27:09 amI can tell you never had a popping fuming Rifa Y or X cap.If you lived through that experience once as I did you would not say that. You replace them when you spot them on older equipment.It takes weeks to get the toxic industrial smell out of your shack, it is awfull and one of my worst experiences with this hobby ever, I rather get zapped with 230VAC than to live through this chemical warfare incident again.Hope you get the point.Back to TS, when it is an electrolytic capacitor this isnotthe case. You just measure ESR if in doubt and replace it if needed.

author: tkamiya
author_rank: Super Contributor
timestamp: August 22, 2019, 06:24:54 pm
content: I have.... mine wasn't that catastrophic. Any time any of power supply components are involved, it has a potential to be very nasty and dangerous. I had a power transformer go up in flame once....My motto is.... do no harm. Unless it's broken already or imminent, I don't touch the component.

author: factory
author_rank: Super Contributor
timestamp: August 23, 2019, 10:46:49 pm
content: What type are they & how old?I've found RIFA PEG124 axial electrolytic caps to be fairly good.By the way there are RIFA plastic film capacitors that look very much like the infamous paper XY types, I found some of the plastic film type in a 1970's calculator, no signs of cracking or smoke.David

author: xmetal
author_rank: Contributor
timestamp: August 23, 2019, 11:58:23 pm
content: Quote from: Kjelt on August 22, 2019, 07:16:54 amI've had this happen with some older equipment of mine and I agree the industrial smell is not nice. I've also had to repair a lighting controller at a local theatre that had a number of these Rifa X caps fail. The inside of the metal case was covered in a black, sticky and smelly mess which was difficult to remove. So I would definitely replace them.

author: pcmad
author_rank: Regular Contributor
timestamp: September 02, 2019, 06:59:24 pm
content: thank you for all you helpful infothe caps in question look ecactly like RIFA PEG124from the advice given i will be doing if its not broken dont fix it there are other non rifa caps that have leaked and some cracked and i will be replacing these onesthank you for your help