[sdiy] P.S. troubleshooting help

[Scott]

Can someone help me troubleshoot my power one hcc-15-3-A?  I took it out of my synth cabinet last night to test it.  It tested fine. (checked for ac ripple w/ the scope, checked to see if it was loosing power when my AC  power drops, etc.. was all fine)
I put it back in my synth today.. doesn't work.  Take it out and test it.  I get 15 volts on the + and .66 volts on the - side.

The pins of the main power transistor on the + side read 15 volts.  On the negative side the pins read 23!  (I'm guessing it should read -15)
Then Im not sure what happens to the signal, because almost everywhere else I test on the - side of the pcb, I read .66 volts. 

I did try replacing the regulator IC (lm723n) (swapped sides, put negative on pos, pos on neg) and the positive side still works fine, so that isn't it.  (If you aren't familiar w/ them, they aren't positive and negative regulators.. they are the exact same chip)

So, having never tried to fix a power supply, and not having the schematics for this thing... im not sure where to go from here.

let me know if anyone has any ideas.  Hopefully that .66 v on the negative side will give someone more informed than me, a clue as to what is going on.
I also tested the transformer, and it is outputting exactly what it should on every 2ndary.

thanks a lot!