Polycon from Fegusson failed - UK Vintage Radio Repair and Restoration Discussion Forum

Cobaltblue · 20th Feb 2021, 9:57 pm

I put in a request for a replacement which was thankfully responded to by Bill (AC/HL).

I have now replaced the offending Polycon cap and have signs of life although a little way to go as there is the usual AF11*,s and to add insult to injury a bunch of Callins caps.

Going to be a day or two before I can get back to it.

I though I would share pictures of the failed capacitor.

Its been a while since I have had to replace a Polycon so I suspect failures of this type are not that common.

Cheers

Mike T

G6Tanuki · 23rd Feb 2021, 7:02 pm

I've seen that sort of failure where someone has given a Polyvaricon 'a good squirt of switch-cleaner' then twiddled it.

The surface-tension of any liquid introduced between the plates and the interleaved dielectric-laminations can make them cling-together enough to tear the dielectric-sheets from their mountings.

20th Feb 2021, 9:57 pm	#1
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,865	Polycon from Fegusson failed I put in a request for a replacement which was thankfully responded to by Bill (AC/HL). I have now replaced the offending Polycon cap and have signs of life although a little way to go as there is the usual AF11*,s and to add insult to injury a bunch of Callins caps. Going to be a day or two before I can get back to it. I though I would share pictures of the failed capacitor. Its been a while since I have had to replace a Polycon so I suspect failures of this type are not that common. Cheers Mike T Attached Thumbnails __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

23rd Feb 2021, 7:02 pm	#2
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Polycon from Fegusson failed I've seen that sort of failure where someone has given a Polyvaricon 'a good squirt of switch-cleaner' then twiddled it. The surface-tension of any liquid introduced between the plates and the interleaved dielectric-laminations can make them cling-together enough to tear the dielectric-sheets from their mountings.