Famicom Won't Turn On but Disk System Does

[TieGuy]

 Hello, for some reason as of yesterday, my Famicom won't turn on when trying to play cartridge games. However, if I plug in the Disk System, it boots up to the SET DISK CARD screen and I can play FDS games just fine. It's the cartridge games I want to play but the Famicom won't turn on. Any ideas why? This used to not be an issue.

 I'm not too good with circuitry or electricity stuff, but the power adapter I use is Input: AC100-240V and Output: DC10V 850mA. I don't use a step-down transformer or anything. I have this singular power adapter split to give power to both the Famicom and the Disk System at the same time. I've done it this way for a while and nothing has happened until now. If you can recommend specific adapters or whatever, that'd be cool. Thank you.

[P]

If disk games works I don't think there is anything wrong with your Famicom, maybe the cartridges are dirty.

The AC-adapter seems fine, although 850 mA may be a bit low current since you split the power to two devices (it's the exact specs of the original AC-adapter but the FDS disk drive takes another 400 mA). If it works fine it might not be a problem though, I guess it could be a problem if you use more peripherals that uses more power.
Since it takes 100~240 V AC input you don't need a step-down though, it will work anywhere in the world.

What ROM cartridge games did you try so far?
Have you tried to unplug the power to your disk system when using ROM cartridge games?

[TieGuy]

What ROM cartridge games did you try so far?
Have you tried to unplug the power to your disk system when using ROM cartridge games?

I've tried many. Like Golf, Mario Open, Pinball, Super Mario Bros., etc. Games that worked just fine before. I don't know why as soon as I played a FDS game, the Famicom refuses to boot up cartridge games. I tried plugging both the FDS and Famicom to the power supply. I tried only the Famicom plugged in. I even tried with an identical power adapter that only plugs into 1 device at a time. Nothing. FDS games boot up just fine but the cartridges won't. I don't understand.

[P]

Well, I guess we could rule out the AC-adapter at least, and since so many games have the same problem the problem is probably in the console.
A dirty cartridge slot could be a problem, but it usually shows itself as glitched screen, not a blank screen.
Maybe the power line doesn't connect to the cartridge.

You could try cleaning the cartridge connector with a toothbrush and isopropyl alcohol and let it dry.
More advanced: if you have a multimeter check for bad traces around the cartridge connector.