[sdiy] Noisy Power Supply

[John Luciani]

On 6/21/07, Scott <Scott at scottwick.com> wrote:
> I did a little more testing on my power supply.  I hooked my scope up,
> and I can see an inverted saw wave on the negative side.
> ----|/----|/----   Sort of like that.  The positive side was flat.  I've
> learned a lot about how to troubleshoot a synth module, but don't know
> where to begin on a power supply.  Is there a common component that
> could possibly cause this problem, or is it not worth trying to figure
> out?

What is the frequency and amplitude of the ripple? How are you loading
*both* of the
outputs? As was mentioned there may be a minimum load required for the
supply to
regulate. Try going to 50% load on the positive output and then vary
the load on the
negative output from 0% to 10% to 50% to 100% and measure the frequency and
amplitude of the ripple.

The problems I have seen in power supplies are usually fans or
electrolytic caps.

(* jcl *)

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