[PlanetCCRMA] Re: Delta 1010

[Richard Humphrey]

Hi-
  Yes, I've replaced these caps in several 1010s. The ones I replaced were 35
volts, if I remember correctly. This was clearly too low and I think the
replacements were 63V, but they may have been 50V. The circuit is a voltage
quadrupling bridge, and the input is 9VAC. This should require at least 48v
caps, (9VAC is about 12Vpeak),  and this assumes the 9VAC doesn't run hot,
which it almost certainly does.

  I think the problem here is they used CHEAP, rather than inadequate caps. 63
is plenty. If you replace them with better ones, you should be fine.

=Rich

----------------------------------------------------
Richard Mortimer Humphrey
General Specialist

---------- Original Message -----------
From: Mark Knecht <markknecht@gmail.com>
To: Fernando Pablo Lopez-Lezcano <nando@ccrma.Stanford.EDU>
Cc: Matt Barber <brbrofsvl@aol.com>, planetccrma@ccrma.Stanford.EDU,
mortimer@ccrma.Stanford.EDU
Sent: Wed, 20 Oct 2004 11:04:53 -0700
Subject: Re: [PlanetCCRMA] Re: Delta 1010

> Since there is almost certainly nothing on this board using 63 volts
> it might be argued that the capacitors were jsut defective and 
> another 63 volt one could be used in it's place. If someone had a voltmeter
> you could pretty easily (granted, with a PCI extender card which
> normal users probably don't have) look at the voltage actually on the
> cap and choose a value higher than that by some margin.
> 
> On 20 Oct 2004 10:42:11 -0700, Fernando Pablo Lopez-Lezcano
> <nando@ccrma.stanford.edu> wrote:
> > On Wed, 2004-10-20 at 06:42, Matt Barber wrote:
> > > ->It is probably not (entirely) due to heat problems. Most probably the
> > > voltage rating of the capacitor is on the edge and it degrades over
> > > time. Just see if you can find something of about the same size, same
> > > value but higher voltage rating. I think the ones in which we replaced
> > > the caps are working just fine. <-
> > >
> > > This one is 470 uF, rated for 63v ... what would be an appropriate value
> > > to look for?  And if we decide to do this, should we change the other
> > > one that's just like it and which looks like it's part of the same
> > > group, but which doesn't seem to have sustained damage?
> > 
> > I'd change both. I don't know what's the next step up from 63V... it
> > also depends on the physical size of the replacement, you have to find
> > something that will fit in the available space.
> > 
> > Richard: do you remember what was the voltage rating of the one you used
> > to fix the 1010's?
> > 
> > -- Fernando
> > 
> > _______________________________________________
> > PlanetCCRMA mailing list
> > PlanetCCRMA@ccrma.stanford.edu
> > http://ccrma-mail.stanford.edu/mailman/listinfo/planetccrma
> >
------- End of Original Message -------