[sdiy] Noisy Power Supply

[Larry Troth]

You can find data on the PowerOne linear supplies at this link:
http://www.power-one.com/resources/products/datasheet/lin.pdf

The reason there is no 'searchable' data is that the part numbers are really
more like BOM id's indicating form factor, voltage, and current choices.

Larry T.

> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl 
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Scott
> Sent: Thursday, June 21, 2007 7:57 AM
> To: synth-diy at dropmix.xs4all.nl
> Subject: RE: [sdiy] Noisy Power Supply
> 
> The supply is an HAA-15-3-A.  The smaller one that works fine is
> HCC15.1.A (1amp at 12 v, .8 at15).
> 
> BY saying the positive is flat, I do mean that there was no ripple on
> the scope.  That was only on the negative rail.  As far as the scope's
> reference, I'm afraid I don't really know how to use a scope!  I just
> have the input going to the positive (or negative) and the 
> ground input
> going to the ground on the supply.  From the looks of it 
> (from what Ive
> seen from observing my synth through it) it looks like the 
> little spike
> on the negative side goes down about 1/2 volt.  The time knob on the
> scope is on 2ms and I get maybe two spikes on the screen at a time.  I
> know that converts into frequency somehow..
> There is no earth ground on the supply.
> 
> Why swap supplies?  The smaller one sure is lighter and takes up less
> valuable cabinet space!  It's because I've got about 26 
> modules in that
> thing.  I've only ever had about 16-18 plugged in at a time.  I never
> ran into a problem w/ not having enough power, but from what 
> I've read,
> I needed a bigger supply.
> 
> One last thing, someone asked is this only when it is under a 
> load, and
> it is actually the opposite.  When I plug it in w/ no load, or w/ only
> one low powered module, the problem isn't there.  As soon as 
> I plug in a
> few more modules, I see the spike.  
> 
> I can also hear a hum from the  supply itself..  (not through the
> electronics, but the thing is vibrating a little)  It does 
> have two big
> caps on it.  I suppose one could be bad.  It is just a used 
> EBAY supply.
> I'd write the guy and complain, but shipping was almost as much as the
> supply itself, so it's almost cheaper to buy a new (used) one.
> 
> I guess there is no way to test a cap, with just a multimeter 
> or scope,
> is there?
> 
> Thanks for all the replies!  I could have never built my synth in the
> first place w/out this group!
> 
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of 
> Needham, Alan
> Sent: Thursday, June 21, 2007 7:13 AM
> To: synth-diy at dropmix.xs4all.nl
> Subject: 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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