RIFA Cap exploded in late 90's TV  - Page 1
Forum section: electronics / beginners

author: Jwillis
author_rank: Super Contributor
timestamp: February 24, 2021, 06:21:47 am
content: Workng on a RCA Colortrak AC/DC manufactured in 1998 that had a bad DC-DC converter . I managed to get that working again and every thing seemed fine when working with DC but when I applied the mains AC , a RIFA X2 PME 285 MB exploded and the 2.5A fuse stayed intact . Voltages looked correct before the incident .I've heard a lot about RIFA caps being a problem or is this just exaggeration ? Or should I be looking for another probable cause?

author: PKTKS
author_rank: Super Contributor
timestamp: February 24, 2021, 08:13:26 am
content: yes it seems they are bad by design and sooner than later they puffffi have nothing on RCA here because they never sold a piece around..but due to the time of these projects it looks like you will have to improvise considering how those designs can be upgraded to todaysthey are much more complex than stuff you have today.. specifically when superimposed over the flyback topology..so look carefully how can you get rid of them...Paul

author: srb1954
author_rank: Super Contributor
timestamp: February 24, 2021, 09:28:19 am
content: Quote from: Jwillis on February 24, 2021, 06:21:47 amIt is no exaggeration about the RIFA caps. They are notorious for spontaneously exploding and releasing a lot of the magic smoke.Just replace the capacitor and if you have an insulation resistance meter check the insulation resistance between the mains active line and the mains earth to check that none of the other capacitors are on the way out.

author: Jwillis
author_rank: Super Contributor
timestamp: February 25, 2021, 12:40:51 am
content: That was the only one . All others are the ceramic 1kV . I don't have a insulation meter but if you have any inexpensive suggestions that would be appreciated.

author: WattsThat
author_rank: Frequent Contributor
timestamp: February 25, 2021, 05:57:57 am
content: The stench is unbelievable when they go fizz burn pfff rather than just a quick pop or pow.You can count on older Hp branded test gear to have one right next to the mains transformer. First thing that I replace when the covers come off. I thought the transformer had lit off when it happened, I was happily surprised to see the supply was still at full output after the smoke stopped. My next thought was how could that much smoke and stink come out of such a small part?

author: srb1954
author_rank: Super Contributor
timestamp: February 25, 2021, 08:38:10 am
content: Quote from: Jwillis on February 25, 2021, 12:40:51 amThe ceramic caps are not likely to fail prematurely. However, it might pay to give them a thorough visual inspection to make sure there is no physical damage, cracks or discolouration of the coating on these caps.You can buy basic insulation testers very cheaply these days. I recommend getting one and regularly checking your equipment. I find that practically all mains capacitors (not just the RIFA ones) and mains filters tend to degrade over time. Checking with an insulation tester can find these imminent failures before they release all the magic smoke.

author: Terry Bites
author_rank: Super Contributor
timestamp: February 25, 2021, 06:27:22 pm
content: See Dave Jone blog on Rifa madness