Electronic Keyboard Power Supply

[MOBoy]

I found a 9V converter (adapter) which I want to use on an electronic keyboard. It states it is for use only with musical instruments. It fits the keyboard but when I measure the output voltage (neg inside, pos outside) it measures nearly 13V. Would it be safe to use?

[HayZee518]

open circuit voltages are always higher when measured.

[sam999]

?! I just threw out a power supply because it was giving me too much volts..

You're saying that was normal because it wasn't in-use?

Oh man..