[sdiy] P.S. troubleshooting help

[Finlay Shakespeare]

Sorry, just noticed how badly worded that was. The negative rail 
outputs -0.6 V both with AND without load.

Cheers!
Finlay Shakespeare
http://www.futuresoundsystems.co.nr

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From: "Oakley Sound" <oakleylist at btinternet.com>
Sent: Saturday, April 04, 2009 7:07 PM
To: "Synth DIY" <synth-diy at dropmix.xs4all.nl>
Subject: Re: [sdiy] P.S. troubleshooting help

> > turned it on a few hours ago and the negative side was below 1V...
>
> Is this with a load?
>
> If so, you should know that dual output Power One supplies will sometimes 
> latch up if the load is too capacitive. Typically, one rail will come up 
> but the other doesn't. Normally, the negative one will not fire up since 
> the positive rail takes more current.
>
> The latching up is likely to happen in modular synths because each module 
> may have a reasonable decoupling capacitance which then adds up when all 
> the modules are in place.
>
> Sometimes the supply will power up OK, sometimes not. The best thing to do 
> in this case is to reduce the amount of decoupling capacitance on each of 
> the modules. I reckon a max of 2uF to 3uF per module per rail and you 
> should be fine.
>
> The other option is to use time controlled power distribution. I think Ken 
> Stone makes a board that does this.
>
> And another option is to modify the Power One to have traditional current 
> limit rather than the usual current foldback method it normally uses. I 
> have done this on a couple of occasions and it works well.
>
> Tony
>
> www.oakleysound.com
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