Odd Power Supply Problem

[kurtlives]

Bought a 12V DC 300mA power supply. Stick my red lead into the centre and touch the black to the side and I get a reading of 12.06V DC. Nice...

When I plug it into my DC jack and touch the + area of the DC jack and have the black lead on the enclosure I get a reading of -12.06v DC.

Why is this happening? Its pissing me off cause my regulator I wired after this is now spitting out a negative voltage as well.

Help?

Thanks....

[frequencycentral]

Sounds like your adapter is:

Ring = earth
Tip = 12 volts

It should be the other way around. does it have a polarity switch? If not, cut the jack off and solder another one on the correct way.

[petemoore]

  Use a reverse protection diode on whatever circuitry is helping you find out if the PS polarity is correct, That and an LED indicator can help save the circuit.
  I have BYOC pedals, FF, TB, etc. and forget what the darn PS scheme is, and it's hard to find inside, and I have trouble accessing information because I forgot about it...a RP diode lets me do a quick 'does it light the LED?' test, with thumb on bypass/LED switch, I plug in/hit switch, if LED doesn't light...polarity must be reversed...
  Not recommended..what is recommended is make certain the actual polarity of the pedal is ascertained, then mark the polarity, make sure any PS's connected match that.