[sdiy] P.S. troubleshooting help

[Oakley Sound]

 > 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