1 VDC Cupling Cap Leakage

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RockinRocket
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1 VDC Cupling Cap Leakage

Post by RockinRocket »

In a cathode follower tonestack I'm getting 1.2V DC leakage through a NOS LEMCO 560pcap.
Very rare cap but like using period correct NOS parts. I have a bunch of these and my personal amp has a 560p in the tone stack as well. Also leaks a little over 1 v.

I burned the amp in over night and it hasn't changed leakage.

The PI entrance cap will block the 1 v but basicaly I have 1vdc floating around the TMB TS.
What can I expect performance wise here?
sluckey
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Re: 1 VDC Cupling Cap Leakage

Post by sluckey »

Scratchy sound when turning pots.
RockinRocket
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Re: 1 VDC Cupling Cap Leakage

Post by RockinRocket »

Thanks Sluckey, The amp is for a customer who wanted NOS parts.
Would you guys replace it with something else?
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Leo_Gnardo
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Re: 1 VDC Cupling Cap Leakage

Post by Leo_Gnardo »

RockinRocket wrote: Fri Nov 09, 2018 6:16 pmWould you guys replace it with something else?
Yes, a cap that doesn't leak. OR try the sometimes-seen method where you block DC to the whole stack with a large value cap, say 0.1 uF, then it doesn't matter if your stack caps are leaky, or low voltage.
down technical blind alleys . . .
Stevem
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Re: 1 VDC Cupling Cap Leakage

Post by Stevem »

He wants NOS parts you say? Well tell him I have 2 sets of 11 gauge flat wound strings that are fully dead, and I pulled them off of my SG back in 68 that he can make me a offer for should he want to really live by his words, lol!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!

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R.G.
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Re: 1 VDC Cupling Cap Leakage

Post by R.G. »

I suspect that the more the customer insists on NOS parts, the fewer hours he/she will actually use the amp, and the less they can tell what the NOS parts do.

Funny creatures, people.

:shock:
"It's not what we don't know that gets us in trouble. It's what we know for sure that just ain't so"
Mark Twain
RockinRocket
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Re: 1 VDC Cupling Cap Leakage

Post by RockinRocket »

Id have to disagree with you RG to some degree.

Those old parts sound different to some degree. Cold be the purity of the metals? More copper? I don't know but the modern equivalent SOZOs vs Mustards, Lemco vs modern CDE mica its noticeable to me. Maybe its all a placebo lol


In the TS I actually am not getting scratchy pots with 1v DC.
RockinRocket
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Re: 1 VDC Cupling Cap Leakage

Post by RockinRocket »

Update and fixed.

Not the NOS parts leaking its the dame Paxoline board Modulus sells. All conductive!! :cry:
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