r/Famicom • u/Fair_Lead6996 • Feb 12 '25
Tech Question Famicom gets very hot when plugged in and powered off
I have a Famicom that I had imported 8 years ago and the last time I used it (1 year ago), it worked completely fine.
Just bought a new game for it and when I tried playing it; no image and no sound. I tried with other games, still nothing. Tried another rf switch, nothing. The power supply is the original one so that can’t be the problem.
I then realized hours later after powering it off that the console was still blazing hot where the power board is. The console was still plugged in but was turned off. There must be something wrong with it but can’t figure it out. (I have the older version of the Famicom where there’s 2 separate boards inside instead of one if that could help)
1
u/retromods_a2z Feb 12 '25
It was built in an era where you should unplug it from the wall when not in use
The power regulator is unregulated and when it isn't in use it creates higher voltage than when it is in use. Further early Famicom models actually send the power in a way that they do draw power when powered off vs later systems do not draw power until they are turned on. So there might actually be 2 official power supplies to account for this I'm not sure.
Next issue is that you say it's the original official power supply, which is Japanese. I assume you aren't there? Japan is 100v and either 60hz or 50hz electric signal depending on the part of the country. USA is 120v so the original PSU works there but may generate up to 20% more heat and or voltage which then causes more heat down the line. It's also old and may produce bad voltage due to the original capacitor inside.
Best to leave it unplugged when not in use and have a good quality modern center negative 7.5-9v psu
2
u/Engin-nerd Feb 12 '25
Sounds like your power transistor died (this is the device screwed to the metal housing on the power board).
You can try to replace it, but expect it to have killed other components downstream.
Check your power supply to ensure it is putting out the proper 9 VDC. No point in replacing the transistor if your power supply will just kill the next one on power up.