Is this Electrolytic fluid or glue/flux? - Page 1
Forum section: electronics / beginners

author: Digideus
author_rank: Newbie
timestamp: February 10, 2025, 10:04:16 am
content: Hi all,First time posting here. I'm an IT guy with some electronics and AV experience. I have been building guitar pedal kits and even replacing electronic parts in guitar amps and pedals to repair them, so I have some practical experience in electronics.I recently acquired a TEAC CR-H285i CD stereo unit on Ebay that has issues and I am attempting to fix it.The seller had pictures of it on standby power and claimed it didn't do anything else. When it finally turned up, I cant even get it into standby mode. When I did a tear down, the main PCB that houses the standby LED and power button has "cracked" in 3 places. It could have happened in transit, and I have repaired that sort of thing before by running wires across the cracked areas to fix the traces, so I think that part if fixable.My question is really about brown stains on the main power PCB tho. (Pic attached).There's a 2200uF Cap and a flyback type transformer on this board (in the red boxes) with suspect brown fluid stuck to the board coming from them.I would assume that this is Electrolytic fluid so denotes replacement parts needed and cleaning the area with ISO, but it could be something else like flux or even glue.Is there an easy way to tell?My plan is to remove ALL of the caps on the power board and replace them to be on the safe side. Most are 16v so I was thinking of just replacing them all with 25v ones. There's also a suspect inductor coil that looks broken. I have never done a flyback transformer before, but I know they are usually related to monitors and CRT screens as I have seen people change them out on arcade machine boards.wish me luck!

author: elektryk
author_rank: Regular Contributor
timestamp: February 10, 2025, 11:26:23 am
content: Sometimes they use glue on larger caps, you probably won't be able to remove it with alcohol.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: February 10, 2025, 11:34:29 am
content: It is easy to de-solder those electrolytic caps that may have “leaked”, although caps don’t normally have a liquid filling as such (impregnated material between aluminium foil).IPA, or switch cleaner of the non residue variety, will clean the gunge.I have an ESR meter for checking caps, although it is cheaper to just change them.Good luck.SJ

author: RoGeorge
author_rank: Super Contributor
timestamp: February 10, 2025, 11:47:31 am
content: That's glue, often used for bigger size capacitors. Helpful against mechanical vibrations. The capacitors look OK, they might not need replacing. I would fix the broken PCB first, and expect it will work normally without replacing anything.Electrolyte leaks can not be that thick, it is too much to fit inside those caps, and electrolyte leaks doesn't spread that much.

author: CaptDon
author_rank: Super Contributor
timestamp: February 10, 2025, 01:30:03 pm
content: That is a type of resilient glue once known as ply-o-bond. It is cream color when new but as it ages from heat it not only darkens but becomes very conductive. Many SMPS power supplies have failed because of this glue and all of the early Kenwood TS-440 transceivers also failed because of this glue. Forget all of the 'cleaning fluid' suggestions! The easiest way to get rid of this stuff is to scratch it off. You will find that it has become brittle but is still very attached to the PCB. Cheers!!