removing silicon kit from transformers - Page 1
Forum section: electronics / general

author: thunderbuny
author_rank: Contributor
timestamp: October 01, 2016, 10:50:40 pm
content: I would like to know what is the best way to get silicon kit from kopper transformer windings.Annyone a got a idea what to use or how to do it without scratching the pcb?Greets Dave

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 02, 2016, 12:06:46 am
content: May take a couple of tries to get past the language barriers.What is it that you are trying to remove?Is it the high silicon steel used to make the core of transformers? This steel has low hysteresis and so has low losses in transformers.Is it silicone potting material used to keep moisture out and control vibration?Is it silicon in integrated circuits which may have been integrated with a transformer to provide compact functionality?A better understanding of the problem will help in giving a useful answer.

author: thunderbuny
author_rank: Contributor
timestamp: October 03, 2016, 09:08:42 am
content: It's the liquid kind one you use to seal leaks with and or gunk/glu transformer on to pcb's with it's a car amp.

author: jpanhalt
author_rank: Super Contributor
timestamp: October 03, 2016, 10:00:52 am
content: It seems you are concerned about removing a silicone rubber. There is no true solvent for silicone rubber. If one had such a solvent, it would probably destroy the enamel on the transformer windings too.One thing you can do is to carefully remove all of the rubber that you can with physical methods, such as picks, tweezers, forceps, pliers. At that point, you can try solvents that either denature the rubber or reduce its adhesion to whatever it is stuck. Light oil (for example mineral spirits or WD40) at about 10% to 30% in isopropyl alcohol (98% pure or more) helps one scrape the silicone off.As for denaturing there are products on the market with that claim. I have tried a few, and the only one that worked for me was branded McKanica. It contains an aliphatic sulfonic acid, as I recall. The aliphatic part (long hydrocarbon chain) helps it penetrate the hydrophobic silicone rubber, and the sulfonic acid part denatures it.John

author: Jeff_Birt
author_rank: Regular Contributor
timestamp: October 03, 2016, 11:04:44 am
content: Ether (automotive starting fluid) will soften/remove silicone sealant. It works best to remove as much as you can by scrapping.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 03, 2016, 06:19:27 pm
content: I concur with the previous answers. Some technique may help. I have found that cutting the potting into long strips with an Exacto or similar sharp blade can help in pealing it away. Choose the cut lines to minimize chances of damage to your PWB. A hard nylon scraper can help in loosening the strips and minimizes the damage to PWBs.There are many different chemical formulations for these silicone potting materials. While some solvents are at least partially effective for some silicone materials, it is impossible to guess (without a really high power laboratory) which kind of potting material you have, so you would either have to try all of them until you got lucky, or in my opinion just stick with mechanical removal.With the best tools it takes time and patience.

author: jpanhalt
author_rank: Super Contributor
timestamp: October 03, 2016, 06:42:04 pm
content: @CatalinaWOWYour comment about hard nylon scrapers reminded me of "plastic razor blades". They are like old fashioned double-edge blades, but made of plastic. Use them in a regular razor blade holder. Several places sell them. A good place to look are boat stores, as they are useful for scraping stuff off fiberglass boats without harming the surface. I use them all the time.John

author: thunderbuny
author_rank: Contributor
timestamp: October 04, 2016, 11:37:28 am
content: Ok thx this was helpfull i gonna try what you folks said but will do it carefully as i need it to work after i removed it lol.this is my 4 chann compo amp already did my 2 chan sub amp but was a pain in the ass did it carefully with screwdrivers etc and i wondered there should be a more easy way but from what i am hearing now it's grab the screwdriver againi made a pic so you can see what i meani want to get more solder on it as the upper side is really crappy solderd.and offcourse they ganked the blank transformer leads and solder pads up

author: DTJ
author_rank: Super Contributor
timestamp: October 04, 2016, 12:04:17 pm
content: That looks like regular RTV as sold by hardware stores.Some hardware stores sell a solvent for removing silicon RTV from bathrooms. Perhaps try that.Something like this:https://www.bunnings.com.au/selleys-375g-silicone-remover_p1232412The label says 8% H2SO4 - not sure I like that as a solvent.This one seems to be mainly acetone:https://www.bunnings.com.au/lift-off-125ml-silicone-and-caulk-remover_p1560136https://2ecffd01e1ab3e9383f0-07db7b9624bbdf022e3b5395236d5cf8.ssl.cf4.rackcdn.com/Product/d582b56b-f057-417b-880f-c603e7d12b3b.pdf

author: jpanhalt
author_rank: Super Contributor
timestamp: October 04, 2016, 12:22:56 pm
content: @DTJ Sulfuric acid denatures silicone. It doesn't dissolve it per se. The sulfonic acid I mentioned is actually a strong acid very much like sulfuric acid, but it has a hydrocarbon side chain bonded to the sulfur that makes it penetrate silicone better. This Wikipedia article describes sulfonic acids (https://en.wikipedia.org/wiki/Sulfonic_acid). Normally, sulfonic acids do not release sulfuric acid.@thunderbunyThe material in the picture could be a hot melt glue. Is it soft and rubbery like silicone or stiffer? If it is hot melt, then some of the recommendations change. Hot melt probably can be dissolved to an extent.John

author: thunderbuny
author_rank: Contributor
timestamp: October 04, 2016, 01:10:07 pm
content: Thank you for the link, I gonna get remover and then first try on a old junk board to see what happens, The copper is not what i am affraid of but the the solderpad is what worries mePS. it's the same stuff you use for kitchen sinks and bathroom it's soft.Here is a pic from the subwoofer amp that i already have done but it was a long job to get it done.ohhh and look at the baddass speaker cables i solderd in!i alway redo amps to get the internal losses as little as posible as it will increase output power but 1.5mm2 cable on a 2KW rms output!

author: thunderbuny
author_rank: Contributor
timestamp: October 04, 2016, 02:51:52 pm
content: Ohhh for the ppl who want more pics and specs.both are ground zero hydrogen amps GZHA 2350XII GZHA 4150XIISub woofer amp is 1480W rms @ 2 ohms fused with 120Amps class AB.4 channel amp 4x 200RMS @2 ohms fused 80 amps class ABRunning fully active, 2 channel for 16cm woofers and 2 for tweeters no passive stuff between amp and speakers just the speaker cable no passive filterssub ampcompo ampit drives a 15 inch rockford sub bridged @ 2 ohms and 2 pair of focal compo sets so all 4 channels running @ 2 ohms too.

author: thunderbuny
author_rank: Contributor
timestamp: October 04, 2016, 10:51:34 pm
content: ohh did i show amps in action?let the electrons flow!

author: BradC
author_rank: Super Contributor
timestamp: October 05, 2016, 02:01:46 am
content: Make sure you put some neutral cure silicone back in there when you are done. Manufacturers don't put that stuff there for no reason, and the extra level of mechanical support it gives is important, particularly if you are driving a massive vibrator.

author: thunderbuny
author_rank: Contributor
timestamp: October 05, 2016, 10:21:53 am
content: yes i will do as you see it's above on a nice vibrating plank! i am not kidding when i turn it up to max power you have a mini earthquake! just why why not put a bit of solder on it! why have a double board but onley solder the bottem [art of it and not the top part? jeez i dont get it!, dave make a nice vid explaining why they did not solder top of board jeez ammatures!PS look this is all original not hacked and the thingy's glued on caps are dancing around in the amp! sais it all, now it got a lot more power so yes dont worry ill make shure transformers cant move lolthose were gued on there becouse it had a plexi/acrylic cover but i had to take it off these amps are great in pumping out power but both amps would go in thermal protection with a ambiant temp of 20C! onley way not to have them hit protection was to take off the covers!german engenering??? more like beeing cheap basturd germans!