How to determine polarity of potential Famicom power supply

[Satoshi_Matrix]

I have a small and compact DC 9v 1amp power supply that's from something or another but it does not list what polarity it is. It has a barrel plug which would fit a Famicom, Super Famicom or model 1 Genesis and I'd like to use it with one of those which I know needs a negative center barrel plug, the + ---C--- -

I have a multimeter, but it doesn't seem to help me find out this information either. Luckily, I can take it apart, and I've taken photos of the board.





I know that vcc lines are red and ground is black, but it seems the red line goes to the side of the large capacitor that has the stripe, meaning that's negative. odd. I simply want to know how to tell what polarity the adapter is. if its center pin positive, I should just be able to desolder the two barrel plug wires and swap them correct?

Thanks for any help.

[Anapan]

Use a volt-meter set to 9 volts on the output with the red probe on your +/red output. if it reads positive 9 volt you're good, negative or no response and you need to swap the polarity. The probes on your multimeter Should be labeled. There's a thread here all about power adapters.

[ApolloBoy]

Use a volt-meter set to 9 volts.

Multimeters don't test for specific voltages, they test for different ranges. In this case what you want to do is set your multimeter to its second lowest DC voltage setting, and then place the red probe on the barrel and the black probe inside the tip. If it's tip negative, you should be reading some kind of voltage; if it's tip positive you won't get anything and you need to flip the probes around to get a reading.

[Hobie-wan]

If it's tip negative, you should be reading some kind of voltage; if it's tip positive you won't get anything and you need to flip the probes around to get a reading.

Some multimeters will show negative voltage if you have it wrong. I'm pretty sure my current and previous ones did this.

[CRTGAMER]

If it's tip negative, you should be reading some kind of voltage; if it's tip positive you won't get anything and you need to flip the probes around to get a reading.

Some multimeters will show negative voltage if you have it wrong. I'm pretty sure my current and previous ones did this.

This. Most digitals will show that negative, dials would have the needle try to jump lower then zero.

@ Satoshi - Maybe just read the barrel without going inside the PCB? If its backwards then reverse the power leads from the brick to the barrel.