High Voltage "snot" Insulation glue? - Page 1
Forum section: electronics / repair

author: joesipaq
author_rank: Newbie
timestamp: August 23, 2016, 05:08:34 pm
content: Hello all, I am a new user here but have been loving the youtube channel.My question today is regarding the replacement of 2 HV Starting caps for an XENON lamp. The caps are listed as 7.5KV and in a past project I have had problems replacing the insulation material that has been gooped on over the solder joints to prevent arcing. The existing glue/gel is still flexible, transparent and also conformed very well to all the nooks and crannies when they put it on. Can anyone point me in the right direction for this type of insulation material? Attached are some photos of how it looks before disassembly.Thank you for the help and advice!

author: LabSpokane
author_rank: Super Contributor
timestamp: August 23, 2016, 06:26:41 pm
content: I think that's conformal coating and is there more as a protectant rather than a dielectric. If you want to reapply, MG chemicals and others sell it in a spray can.

author: joesipaq
author_rank: Newbie
timestamp: August 23, 2016, 06:44:46 pm
content: Thank you for the reply! I will check into what is offered for the Conformal coating as I would like that too for some future projects! This one however is (also?) a dielectric (do they sell a conformal coating that is also designed to be a dielectric?). Without it, the voltages will jump between pins. Some reason the second picture I tried to upload didn't succeed so I will upload it with this response. Thanks for getting me in a good direction!

author: SeanB
author_rank: Super Contributor
timestamp: August 23, 2016, 07:05:11 pm
content: To reduce the arcing simply make every solder joint using enough solder so there are no sharp points there, that will reduce it considerably. Sharp points in high voltage will always arc, but a nice round joint will never do so till the voltage gets a lot higher. You make the joint with little solder, cut the leads flush then add more solder to make them rounded and smooth with no lead showing underneath.

author: helius
author_rank: Super Contributor
timestamp: August 23, 2016, 07:43:56 pm
content: You can use a product called MG Chemicals 4226 Super Corona Dope. This is specifically made to prevent arcing and tracking between HV points.

author: joesipaq
author_rank: Newbie
timestamp: August 23, 2016, 09:38:13 pm
content: Thank you all! I will make sure I do some touch up soldering after flipping the legs off to keep sharp edges down. But this is something that need to not have arcs - Not just a reduction. Also on the silk screen side of the board, it would still arc between components that are close.Thank you very much Helius! That looks like it would work perfectly! Do you know about its removal for future component replacements?

author: richnormand
author_rank: Unknown
timestamp: August 23, 2016, 10:18:32 pm
content: I use the MG 4226 corona dope (yellowish transparent). First make sure there are no sharp points, then I use the dope on it and all the incoming wires. Wait a bit and do a second coat. Then I wait a few days and use transparent GE silicone II RTV (bathroom caulking stuff) to make a big blob over and encapsulate everything. I had no issues up the 35kV.....yet.....

author: helius
author_rank: Super Contributor
timestamp: August 23, 2016, 10:37:18 pm
content: Quote from: joesipaq on August 23, 2016, 09:38:13 pmIt's a varnish, so straight toluene or even lacquer thinner could be used to soften it for removal. You need to be quite careful with solvents like these that they don't contact any plastic packaged components.