[sdiy] Noisy Power Supply

[jean-pierre.desrochers at ville.quebec.qc.ca]

If it's a linear supply:

I've seen that ripple some times in badly coupled
DC power supplies path. ----|/----|/----
'V' grooves at 120hz in dc often means
badly soldered or open filter cap..
What you can do is unplug the synth from
both DC supply's path then load it with
power resistors that would draw around 80%
of each DC path available current.
Then if  the 'V' shaped grooves are still there
put a large cap in parallel with suspicious large caps
that are in big uF values.. Obviously on at a time..
Make sure you unplug the supply before doing so. 
If the ripple stays there then this could
be something else in the supply.. but you'll be
sure the problem is the supply.. not the synth.
Hope this helps.

Jean-Pierre Desrochers



-----Message d'origine-----
De : Needham, Alan [mailto:Alan.Needham at centrica.com]
Envoyé : 21 juin 2007 08:13
À : synth-diy at dropmix.xs4all.nl
Objet : RE: [sdiy] Noisy Power Supply


Could this be model number HC15-3-A ?
      Floating 15v at 3A, remote sensing ?
        (I can't find anything like 15v 0.8A - what is it ?)

You say the positive side is flat ??? do you mean the 'scope
sees no ripple here, what is your 'scope's reference connected to?

If the second supply is only 0.8A and is running the synth OK,
   why swap?
   is it's output floating?
   is there an earth connection anywhere on the DC supply side?

	Alan, peering out of his cave

#  -----Original Message-----
#  From: synth-diy-bounces at dropmix.xs4all.nl
#  [mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Scott
#  Sent: 21 June 2007 5:57 AM
#  To: synth-diy at dropmix.xs4all.nl
#  Subject: [sdiy] Noisy Power Supply
# 
# 
#  ----|/----|/----   Sort of like that.  The positive side was flat.

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