SO, I accidentaly connected a NES AC adapter on a genesis.

Firstly, I know you should never do that as the NES brick outputs AC, never done it before but it just happened accidentally.
I had both Bricks on my test bench power bar and accidentally used the NES one on the genny because the connector just looks the same ( of course... )
I usually dont have NES adapter there so I kinda forgot about it. I just connected it there for 5 min the other day to test a few connectors and left it there...

Anyway. Genesis made some very funny graphical glitch on the screen so I quickly shut it down. It ran for maybe 5 sec.
I then checked all the setup and noticed the wrong adapter ( Doh!!)

I switched to the right adapter and genesis appears to be fine. But Im kind of worried it might have done some hidden damage. Can't be good for the machine.
I checked the NES adapter and the polarity appears to be HOT-Center. Which means I sent AC voltage to the ground of the whole motherboard. ( was a model 1 )

I would like the opinion of the more experimented techies about how bad this actually is for the motherboard.

 

If it appears to be fully working, it would appear that nothing was damaged. You got lucky.

Having made this mistake myself I got rid of the NES transformer and only keep a DC adapters around.

 

I'm guessing model 1 Genesises are tougher when it comes to taking electrical abuse. I also plugged in a AC power brick but didn't damage the unit.

 

I did something like this once too. My unit lived. Those heavy chips found in the model 1 (minus VA7...) are really hard to kill.

 

Ive done this with a US snes mini too, fortunately the very first thing in the circuit is the voltage regulator, which pretty much stops the AC from touching the internals. Blown fuse/voltage regulator is usually the worst that happens in that case.

 

Easy answer to prevent this happening in future - move to the UK. Our Nintendo PSUs have blue plugs on the end

 

Haha, yeah, I think I will use a DC adapter for the NES from now on, since they can use it as well.
I will just lock away those evil AC brick somewhere, they are a freaking hazard.
Good to know the regulators will stop the AC, or most of it.

Ive done a bit of research and tried to think about what is happening in the circuit when you plug in AC instead of DC.
-Firstly I concluded that which side is hot on a AC adapter is irrelevant for the electric circuit in a circumstance like this.
-If there are filter caps connecting DC input to ground they would take a severe beating as AC would likely flow through them.
-Assuming regulators stop AC, all the internal should be spared the worst as Bad_Ad said.

IF hypothetically AC could go through the regulator, or you had no regulator, then I guess It would be roughly the equivalent of everything on the board being powered on and off 60 times a second with the wrong polarity and possibly the wrong unregulated voltage. I cannot imagine this being anything but disastrous.

 

Regulators don't necessarily stop AC; and most will die if Vo is greater than Vi.

 

Or even easier, move to Japan. They use DC PSUs for the Famicom, which can even be used for many other systems, including the Mega Drive. Problem solved.

 

How reliable is that? 850ma PSU on a system who includes 1.2A.

 

Would you guys consider it a sacrilege if I threw all my original NES AC adapters in the garbage?

I am hesitant to even sell them on ebay as it may help shorten the average worldwide lifespan of non-Nes consoles.

 

If you don't want them, sell them. Not everyone is a rash, disorganized idiot!

Here's how I tell the difference:

Nintendo PSUs have NINTENDO written on them. Sega PSUs have SEGA written on them.

You should never leave a PSU plugged in, anyway. So when you go to plug it in, CHECK.

And if you REALLY can't cope with that, label your damn plugs!

 

Assuming the Genesis is the same as this Japanese Megadrive I have here, there are some diodes connected between the power input and the regulators, so the only part that would have had the AC applied to it was the very first input filter cap - which is a 22nF non-polarized type. The main input filter cap (220uF, 16V electrolytic) is on the other side of the diodes next to the regulator input, so it would not have been exposed to the negative half cycles.

 

Yes!! It has them too!!
I actually checked those diodes yesterday but retardedly assumed one side of em would connect to ground to let the inverted current short circuit the AC adapter, since they were not connected to ground i ended up thinking they were for something else than protection. And did not even check if they connected to the power input. *Self facepalm*

Now that I think back on it that would make no sense to do it the way I tought It would be. Thanks for lighting up my lightbulb!
Rep up!


So basically what I did to my genesis is roughly the equivalent of turning it on-off about 300 times in 5 secs. (60hz * 5 sec )

 

Pretty much, yeah. And the way you thought it was wired up was not that unreasonable - I've seen equipment with (normally reverse biased) diodes wired across the power input so they will blow the fuse if you hook them up backwards. The advantage is that you don't get the 600mV or so voltage drop across the diodes in normal operation.

By this logic, it would be perfectly valid to connect a UK SNES PSU up to a Super Famicom - after all, they both have "Nintendo" on them...

 

I am shocked by your vehemence

If leaving AC adapters connected on my test bench power bar makes me a disorganized individual, then Yes I am guilty of that ( I do turn off the power bar when not in use though )
But I dare say mere disorganization is trivial compared to the magnitude of the randomness and cluelessness that characterizes the human race as a whole.

By this logic, by not selling those AC adapters, am i not potentially rendering to the average human, who would probably eventually misuse the said item, a great service?

 

Well, technically a repair bench should use a proper variable test PSU, and if not I would expect the PSU to be checked before connection, so it's a little careless, shall we say

However, what I meant was that you are condemning everyone else as being idiots. What if someone has a Nintendo, and only a Nintendo, but their PSU died? They are never going to have a Sega to inadvertently kill. Do you really want to deprive them of Nintendo gaming goodness?

Some people just like having the right PSU for their collection, but may already use a DC adapter - perhaps that's what they got with it. Maybe they just keep the console on the shelf!

 

Did I say repair bench? Im talking about the test bench, its a different bench. And I only use known good PSU for testing. But in the specific case of the NES PSU I would rather say: "known evil".

I am not condemning them to be idiots. But I am estimating there are good chances that they might be. Am i not the living proof that idiots do exist?
The person you describe could still use just about any 9v-12c DC adapter that is still in production and enjoy the Nintendo goodness just as well as if it had "nintendo" molded in the plastic.

Well, Ill have to admit that this concept is kind of alien to me. These adapters do not have anything unique, irreplaceable or special beside having the Nintendo logo molded in the plastic. To me this is not of much value. By contrast, a genesis, for instance, contains many unique and out of production electronic parts that cannot be replaced by new parts once they are fried.




( I hope no one is taking this exchange too seriously )

 

Yeah, what kind of idiot only has ONE bench for their tinkering? Scrubs.

 

Least it wasn't a Sega CD right? That's how I got my boxed Sega CD. All it cost me was the price of a new fuse.