Multi-meter: first step in troubleshooting

[TheWeaze1]

Hey there... I was reading the "what to do when your box doesnt work" article so I got the multi-meter from the garage.  I set it to 20 DCV... the article says 10V or 20V... I assume this is correct.  There are three places to plug in the wires.  Com, V ohm mA, and 10ADC.  I put the black wire in com and the red wire in the V ohm mA port.  (There are unfortunatly no instructions for the multi-meter--it is made by Cen-Tech.)  I first tested my wall wart.  It is set to 9V  i put the red wire insde the plug and the black wire on the barrel and the meter says 17.3.  I don't understand this.  Any help? thanks guys.

[littlegreiger]

Unfortunately that reading might be right. Most wallwarts are not regulated and can go very high in voltage. Try testing a 9v battery and see what it says.

[The Tone God]

Most cheap unregulated adaptors are just diodes/rectifiers with a big cap on the end. They are rated under load. When unloaded they will read high. Plug the adaptor into a load like a proper value resistor or device and meassure it then, You will see come closer to 9v.

Andrew

[Basstyra]

First, when you plug a wallwart on a circuit (pedal or else), the voltage will drop. If it's not regulated. An unregulated 9v wallwart, when not feeding a circuit, will be more at 12v. Or more.

It's all about a power supply with or without load.

[TheWeaze1]

Hey thanks for the posts!  I was wondering if it would hurt my pedal if I had the wall wart set to 12V instead of 9V... I guess that helps answer my question.  I am having a problem of: the bypass setting works fine (DPDT switch) but when ran through the ciruit it is very quiet.  It is a simple distortion pedal, my first try at this.  The volume pot works fine, but as I said it is very quiet, and... no distortion!  When I had the thing hand wired it worked fine but when I soldered everything together it does this.  So I am trying to go through that "when it doesn't work" post.  Thanks.