Have a ntsc master system that powers on but has no sound and a black screen. Tried the rf adapter and the av cable makes no difference. TV recognizes it's on but just has the black screen. Voltage regulator tests 9v on left leg and 5v on the right so that should be fine. Anything simple to check next? Thanks in advance
Follow up: switched ac cord to a different one and then master master system would boot up but not read cartridges, snail maze would work. Not sure why the led would light up with old adapter but not display anything else. I couldn't see any cold joints on the cartridge slot but touched up all the joints on it and now its works again. Glad to have it back and pretty simple fix.