Originally Posted by iiipopes
Some of the newer designs have diodes from the battery to the preamp to prevent voltage from leaking through and damaging the preamp. If you think it is already dead, then it wouldn't hurt to reverse it again to see if this is the case. If the diodes are there, they would block all voltage and the preamp would have zero output.
Yes, all 9 volt battery devices SHOULD have diodes, but unfortunately some don't. Obviously it's really easy to put the battery in backwards and touch the wrong terminals reversing the voltage even though it won't snap in place. I trashed one of my G&Ls this way. It burned out the integrated circuit (bug). It wasn't potted and the ICs are cheap (little over a dollar). I put in an IC socket for next time.
So yes, do try it back wired right and see if you got lucky if not, just remember the rule:
Transistors make better fuses than fuses.
By the way, I now power most of my basses over a TRS stereo cable from the amps. Just use a one-spot inside the amp. Works just great. for most basses all you have to do is short the battery clip and it works since the battery negative usually goes to the "ring" contact. No special connectors needed. Cool thing is it lets you install all kind of "current hog" things like neck marker LEDs. And should your power supply die, you can always unclip the battery short and put the bass back to battery operation. I wire it so all "current hogs" only work from the supply and not from the battery.