AC Adapter Question

[SuperMuppet]

I have a question regarding AC Adapters. I was wondering, could a North American Sega Genesis AC Adapter (1602) work on an AV Famicom? I am asking this as I plan to get an AV Fami, and I do not want to spend too much money on extra peripherals. I can't find any straightforward and easy answers to this question anywhere, they usually involve the original Famicom.

[chowder]

Yes, the model 1 Genesis adapter will work.

[SuperMuppet]

is it 1602, 1602-1, or both that should work with an av famicom?

[HokusaiXL]

Both will work, 1602-2 is for the model 2, 32x, and gamegear

[mfm]

I have a question regarding AC Adapters. I was wondering, could a North American Sega Genesis AC Adapter (1602) work on an AV Famicom? I am asking this as I plan to get an AV Fami, and I do not want to spend too much money on extra peripherals. I can't find any straightforward and easy answers to this question anywhere, they usually involve the original Famicom.

It works but it's probably not good for the AV Famicom in the long run. I used the equivalent Megadrive 1 adapter for Europe and that output too high voltage which heated both the console and the cartridge. I don't know if the American version has the same problem but you should at least check if your console gets warm.

[chowder]

It works but it's probably not good for the AV Famicom in the long run. I used the equivalent Megadrive 1 adapter for Europe and that output too high voltage which heated both the console and the cartridge. I don't know if the American version has the same problem but you should at least check if your console gets warm.

It won't be a problem, the Famicom uses a 7805 voltage regulator that can accept much higher input than 10V.  It will get marginally warmer, but nothing to worry about at all.

[HokusaiXL]

Old consoles producing heat is super common because of the old linear power supplies.  Extra voltage has to so somewhere, so it gets converted to heat.  You'll be fine so long as you don't pump more than 12 volts into the system.  While it's still within the 7805's accepted voltage range, the heat sinking properties of the RF module shield probably can't sink enough heat from the regulator to handle the voltage increase by more than 2-3 volts.

[chowder]

The 7805 has internal thermal protection, so it should should down rather than do any damage anyway.  The wrong polarity on the other hand, might not be so kind

[mfm]

It won't be a problem, the Famicom uses a 7805 voltage regulator that can accept much higher input than 10V.  It will get marginally warmer, but nothing to worry about at all.

The AV Famicom was significantly warmer when using an MD1 PSU compared to a 9V switched PSU.

Old consoles producing heat is super common because of the old linear power supplies.  Extra voltage has to so somewhere, so it gets converted to heat.  You'll be fine so long as you don't pump more than 12 volts into the system.  While it's still within the 7805's accepted voltage range, the heat sinking properties of the RF module shield probably can't sink enough heat from the regulator to handle the voltage increase by more than 2-3 volts.

The MD1 adapter I measured was doing 14V.

[chowder]

The MD1 adapter I measured was doing 14V.

Then it was faulty or one of those cheap Chinese knock-offs.  Which are faulty straight out of the factory

[mfm]

Then it was faulty or one of those cheap Chinese knock-offs.  Which are faulty straight out of the factory

It's an original from SEGA and I have two of them. One measured 14V and the other one significantly heats up my AV Famjcom. It's unregulated so it probably doesn't output what you think it does.

[chowder]

It's an original from SEGA and I have two of them. One measured 14V and the other one significantly heats up my AV Famjcom. It's unregulated so it probably doesn't output what you think it does.

If it's unregulated you'd need to measure it under load to get the true value, it'll be lower than 14V.  I question the wisdom of using such old power supplies anyway, but that's another topic

[mfm]

If it's unregulated you'd need to measure it under load to get the true value, it'll be lower than 14V.  I question the wisdom of using such old power supplies anyway, but that's another topic

I could but the heating is proof enough that the voltage is too high. And one can't talk around the fact that heat is not good for electronics. Regardless what the datasheet for the 7805 datasheet says it's also heating other components in the console and in the cartridge.

People coming to a specialized forum such as this should expect a better answer than "it kinda works", they can get that kind of advice in a lot of other places.

[HokusaiXL]

Only thing I can suggest is checking the voltage behind the power connector on the famicom when a game is running to check the incoming voltage.  Other than that, chips heat up under load.  On both the famicom and in the cart (as some carts have additional ram and sound chips), though they shouldn't be more than warm at most.

While yes this is a specialized forum for these kind of things, no one claims to be an expert in the field.  Want an expert, search for an engineer.  We're hobbiest at best.

[chowder]

All regulators get warm, that's why they attach them to a heatsink.  The 7805 has thermal protection, if it was too hot it would stop working.