Blown Power Supply?

Thread Starter


Joined Nov 5, 2011
I just got a script 90 (led + dc) I was so anxious to test it and had no 9v batteries so I gathered some old walwarts and grabbed one that (I thought) was suitable ie 9v dc @ 450 ma. I plugged it in and the led came on, then whent dim and then went off. Upon inspection I discovered that it wasn't 120 v ac to 9v dc, it was 120v ac to 9v ac! Now the box doesn"t work (except by-pass) no led and no effect. How much damage have I done and is it fixable? Thanks,


Joined Mar 24, 2008
A LED is a diode, you must use a resistor when using one. You would have blown any power supply your tried using this. I have written a tutorial on LEDs, then went on to write a lot more. To understand LEDs you need to cover Chapter 1 and half of Chapter 2.

LEDs, 555s, Flashers, and Light Chasers

It sounds like you blew the transformer (or it would have not faded out). Generally wall warts are not meant to be repairable, though I have done it by carefully cutting the case in half and replacing the fuse.


Joined Jul 9, 2011
Are you talking about this one?

Did you open it up and is it this board?

I don't have schematic or something but it should be able to repair this putting some effort in to it.


Joined Jul 17, 2007
OK, in this thread you mention a "script 90", in the other thread you mention a "phase 90".
What is the actual name of the effect pedal?
Is it a homebuilt, or a commercial one?
If commercial, what's the exact model?
Here's a link to an old Phase 90 design:
More hits in this Google search:,cf.osb&fp=44eaab8c14888b01&biw=1268&bih=731
MXR Phase 90/180

You may have fried all of the opamps and diodes. It'll be tough to tell remotely.