I was testing some Sega Master System 2 vintage game consoles with a friend and we couldn't get a signal out of them. I used a portable TV with analog tuning to look for the RF signal and nothing. So we tried a different antenna cable, checked the wallwart output, cross-checked with a C64.... Then we found the original Sega PSU and .... OPS! ... SMS2 uses the "Japanese" polarity with (+) on the outer ring and (-) on the tip.
A cold shiver hit us: had we fried all three consoles? Were they already cooked (probably)? Regardless we tried with the right PSU and the signal was there on UHF channel 36 (about 603 MHz)!!
The good news is that Sega used a polarity reversal trick of some kind, but they forgot to put a "power on" LED. The required voltage is 9V.
Happy retroconsoling!
