Capacitor identification "RS" - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

McMurdo · 20th Apr 2021, 11:52 am

I'm not a fan of those mixed dielectric caps either, I've seen a few go short. I would replace them 'again'. But do it for reliability's sake, I doubt replacing functional ones will make the sound any better.

dazzlevision · 20th Apr 2021, 11:59 am

I have quite a few Dubilier, TCC and Hunts “NOS” paper and mixed dielectric capacitors in my stock/vintage collection and they all have significantly reduced insulation resistance. Even such types fitted in metal cases and “rubber” sealed and crimped over ends are defective in that regard. So, unless “restuffed” with a modern plastic film type, I would never use them in valve equipment or in a circuit position where dielectric losses were important.

Maarten · 20th Apr 2021, 12:27 pm

Mixed dielectrics don't short or go leaky as often as paper caps, but instead they go up in capacity if the paper part fails. They should at least be measured when encountered.

JellyBelly · 21st Apr 2021, 5:31 pm

Thanks guys. Absolute goldmine of info, backed up with personal experiences.

So I will replace them on the following grounds
1. They aren't original anyway
2. I have already replaced the last original paper ones with new yellow ones.
3. On balance they may fail soon or drift away from their spec values.

more work to be done, more to learn

HamishBoxer · 21st Apr 2021, 5:46 pm

Not electrolytic and they certainly fail and have done for a few years now, certainly in "Boost Cap" positions in TV's.

20th Apr 2021, 11:52 am	#21
McMurdo Dekatron Join Date: Jun 2009 Location: Staffordshire Moorlands, UK. Posts: 5,269	Re: Capacitor identification "RS" I'm not a fan of those mixed dielectric caps either, I've seen a few go short. I would replace them 'again'. But do it for reliability's sake, I doubt replacing functional ones will make the sound any better. __________________ Kevin

20th Apr 2021, 11:59 am	#22
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,608	Re: Capacitor identification "RS" I have quite a few Dubilier, TCC and Hunts “NOS” paper and mixed dielectric capacitors in my stock/vintage collection and they all have significantly reduced insulation resistance. Even such types fitted in metal cases and “rubber” sealed and crimped over ends are defective in that regard. So, unless “restuffed” with a modern plastic film type, I would never use them in valve equipment or in a circuit position where dielectric losses were important.

20th Apr 2021, 12:27 pm	#23
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,199	Re: Capacitor identification "RS" Mixed dielectrics don't short or go leaky as often as paper caps, but instead they go up in capacity if the paper part fails. They should at least be measured when encountered. Last edited by Maarten; 20th Apr 2021 at 12:56 pm.

21st Apr 2021, 5:31 pm	#24
JellyBelly Triode Join Date: Mar 2021 Location: Watford, Hertfordshire, UK. Posts: 17	Re: Capacitor identification "RS" Thanks guys. Absolute goldmine of info, backed up with personal experiences. So I will replace them on the following grounds 1. They aren't original anyway 2. I have already replaced the last original paper ones with new yellow ones. 3. On balance they may fail soon or drift away from their spec values. more work to be done, more to learn __________________ Roger ___________ It's never done that before

21st Apr 2021, 5:46 pm	#25
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,930	Re: Capacitor identification "RS" Not electrolytic and they certainly fail and have done for a few years now, certainly in "Boost Cap" positions in TV's. __________________ G8JET BVWS Archivist and Member V.M.A.R.S