Re: Source of ripple in simple PS circuit?

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#2246

From: Dave M.
Date: Wed, 21 May 2003 03:37

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Michael A. Terrell <mike.terrell@earthlink.net> wrote in message
news:3EC9FD41.7CF5E71B@earthlink.net...
> DaveC wrote:
> >
> > Replaced the rectifier bridge. Hum is gone (well, 90 percent of it).
What
> > remains is a quiet buzz that you can hear only if you put your ear to
the
> > speaker. I think all commercial-grade stereos have some buzz in the
output.
> >
> > I suspect that the bridge was under-designed. The current throught the
+15
> > volt circuit is about 1A. The bridge is rated at that. The fuses
(between the
> > transformer and the bridge) were designed to be 2A (as silk screened on
the
> > PCB); 3A fuses were found installed. Makes you wonder...
> >
> > Unit is an H-K model AVR 65.
> >
> > Some ripple (a few tenths of a volt p-p) remains, but the v. reg is
> > responding well and is able to suppress it.
> >
> > Thanks to all who contributed suggestions,
> > --
> > Dave C
> > dave+usenet3016@mailblocks.net
>
>    You probably had an open diode in the old bridge rectifier  Some of
> the early ones would run hot and the internal connections would open or
> become intermittent, as they got older.

We must have forgotten  to tell him to measure the junction drop in the
bridge rectifiers.
> --
>
>
> Michael A. Terrell
> Central Florida

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From: "Dave M." <gadget@frontiernet.net>
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Subject: Re: Source of ripple in simple PS circuit?
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