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Re: Pre-war capacitor
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Cursitor Doom
Apr 28, 2017, 1:44:18 PM4/28/17
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On Thu, 27 Apr 2017 14:29:07 -0700, tabbypurr wrote:
> I have an old EHT PSU to repair. There are 2 capacitors, one paper, one
> plywood! The paper cap, which is uncased, tests as: 420nF 11 ohms ESR,
> 5% loss. I've not yet done a dc leak test, which it needs. What do you
> think of those figures? IME pre-war paper caps are highly suspect. I'd
> rather establish what I can before subbing it, as the construction of
> the whole thing is rather characterful.
I've a few boxes full of oil/paper metal-cased capacitors I could test
for comparison purposes if needs be, Tabby, but I've added s.e.r in case
some kind soul there will know the answer off the top of their heads
first.
> I have an old EHT PSU to repair. There are 2 capacitors, one paper, one
> plywood! The paper cap, which is uncased, tests as: 420nF 11 ohms ESR,
> 5% loss. I've not yet done a dc leak test, which it needs. What do you
> think of those figures? IME pre-war paper caps are highly suspect. I'd
> rather establish what I can before subbing it, as the construction of
> the whole thing is rather characterful.
I've a few boxes full of oil/paper metal-cased capacitors I could test
for comparison purposes if needs be, Tabby, but I've added s.e.r in case
some kind soul there will know the answer off the top of their heads
first.
pf...@aol.com
Apr 28, 2017, 2:58:41 PM4/28/17
to
> On Thu, 27 Apr 2017 14:29:07 -0700, tabbypurr wrote:
>
> > I have an old EHT PSU to repair. There are 2 capacitors, one paper, one
> > plywood! The paper cap, which is uncased, tests as: 420nF 11 ohms ESR,
> > 5% loss. I've not yet done a dc leak test, which it needs. What do you
> > think of those figures? IME pre-war paper caps are highly suspect. I'd
> > rather establish what I can before subbing it, as the construction of
> > the whole thing is rather characterful.
What, if anything, are the markings on the caps themselves?
>
> > I have an old EHT PSU to repair. There are 2 capacitors, one paper, one
> > plywood! The paper cap, which is uncased, tests as: 420nF 11 ohms ESR,
> > 5% loss. I've not yet done a dc leak test, which it needs. What do you
> > think of those figures? IME pre-war paper caps are highly suspect. I'd
> > rather establish what I can before subbing it, as the construction of
> > the whole thing is rather characterful.
You ought to be able to screen a modern film cap to within a very few percent of the OEM values, go high on the voltage parameters, and go from there.
Peter Wieck
Melrose Park, PA
ohg...@gmail.com
Apr 28, 2017, 6:13:28 PM4/28/17
to
Depends which war..
tabb...@gmail.com
Apr 30, 2017, 6:53:02 PM4/30/17
to
On Friday, 28 April 2017 19:58:41 UTC+1, pf...@aol.com wrote:
> > On Thu, 27 Apr 2017 14:29:07 -0700, tabbypurr wrote:
> >
> > > I have an old EHT PSU to repair. There are 2 capacitors, one paper, one
> > > plywood! The paper cap, which is uncased, tests as: 420nF 11 ohms ESR,
> > > 5% loss. I've not yet done a dc leak test, which it needs. What do you
> > > think of those figures? IME pre-war paper caps are highly suspect. I'd
> > > rather establish what I can before subbing it, as the construction of
> > > the whole thing is rather characterful.
>
> What, if anything, are the markings on the caps themselves?
the cap doesn't have a case, let alone markings.
> > On Thu, 27 Apr 2017 14:29:07 -0700, tabbypurr wrote:
> >
> > > I have an old EHT PSU to repair. There are 2 capacitors, one paper, one
> > > plywood! The paper cap, which is uncased, tests as: 420nF 11 ohms ESR,
> > > 5% loss. I've not yet done a dc leak test, which it needs. What do you
> > > think of those figures? IME pre-war paper caps are highly suspect. I'd
> > > rather establish what I can before subbing it, as the construction of
> > > the whole thing is rather characterful.
>
> What, if anything, are the markings on the caps themselves?
> You ought to be able to screen a modern film cap to within a very few percent of the OEM values, go high on the voltage parameters, and go from there.
>
> Peter Wieck
> Melrose Park, PA
NT
pf...@aol.com
May 1, 2017, 7:28:03 AM5/1/17
to
On Sunday, April 30, 2017 at 6:53:02 PM UTC-4, tabb...@gmail.com wrote:
> Of course I can replace it, and probably will need to, I just wanted to know if this thing might still be serviceable, if so I'll let it stay.
The short answer is No.
> Of course I can replace it, and probably will need to, I just wanted to know if this thing might still be serviceable, if so I'll let it stay.
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