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SB
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Adding a reset switch to a SMS2
Post Posted: Sat Nov 27, 2004 11:14 pm
Hi all,

Just a quick query - is it possible to add a reset switch to a SMS2? Any details or links would be appreciated!!

Cheers,

SB
 
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Post Posted: Sun Nov 28, 2004 10:21 pm
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> Hi all,

> Just a quick query - is it possible to add a reset switch to a SMS2? Any details or links would be appreciated!!

> Cheers,

> SB

> >Isn't it just simpler to turn the thing off then turn it back on again? Remeber it will have to be a push button switch such as a doorbell switch otherwise if you hit it and forget to release it all you will see will be a black screen. I ain't got no idea for a mod but pull apart a Mega Drive if you can get one and have a look how it's reset button is wired up. I presume you have a PAL system?
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Post Posted: Mon Nov 29, 2004 11:17 am
Well, I dont have an SMS2 myself. But in theory it could be done with a normaly open momentary pushbutton switch, wired to the power so that when the switch is held in it would close the power circuit and once its released it would open back up.








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Post Posted: Mon Nov 29, 2004 11:40 am
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> Well, I dont have an SMS2 myself. But in theory it could be done with a normaly open momentary pushbutton switch, wired to the power so that when the switch is held in it would close the power circuit and once its released it would open back up.

That would be an hardware reset, not a software one. Software reset is polled by the program (it can be used, for exemple, to do the cheat in Black Belt).
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Post Posted: Mon Nov 29, 2004 2:42 pm
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> That would be an hardware reset, not a software one. Software reset is polled by the program (it can be used, for exemple, to do the cheat in Black Belt).


A VERY good point. (forgot to mention the hardware aspect. Original post does not specify if looking for software or hardware version, I'd have to do more research on doing a software switch. I suppose it can be done though.)
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Post Posted: Tue Mar 04, 2008 2:25 pm
Hi all, don't know if this is written somewhere else on this forum, but for those who would care, this is how to make Reset button work on SMS II
(I am working always with PAL consoles released in Europe, so I cannot confirm this mod universal):

The pin#33 on the SMS I/O Chip is on the SMS model 2 connected directly to +5V.
But on the model 1 it's connected to +5V through a resistor.
Reset switch is connecting the pin#33 with ground. And that is the problem:

When you try to connect this pin with ground on model 2 , you short-circuit the power source!
The solution is easy, but a bit hard to preform because you have to lift pin #33 of the IO chip (this was in my case needed, because the connection of this pin to +5V is made underneath the chip, not on the other side of PCB where it could be simply cut) and connect it to +5V through a resistor (use 1500ohm (1K5) for example).
Next step is to solder switch between this pin and ground and thats it. :)

-verified with SMS Pad Checker-
reset.GIF (1.57 KB)
reset.GIF

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Post Posted: Sun Jan 10, 2021 11:11 am
Do not have a 1.5k resistor have a 1k or 2k could it still be ok?
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