Print Page - Megadrive 2 50/60Hz MOD schematic

Title: Megadrive 2 50/60Hz MOD schematic
Post by: Wakutan on June 23, 2005, 12:24:22 AM

Correct me if i am wrong but isnt the pin 107 already connected to +5V?

Lift the pin 107, so it doesnt connect to the +5V anymore, right?

The trace leads from pin 107 to the solder point of +5V.

And the switch, switches between GND and +5V correct?

Like this:

(http://img257.echo.cx/img257/9978/mdmod6pa.th.jpg) (http://img257.echo.cx/my.php?image=mdmod6pa.jpg)

Please tell if this correct or not.

Otherwise please post a picture/link to a schematic, so i can understand how this 50/60Hz mod really works.

Thanks alot.

Title: Megadrive 2 50/60Hz MOD schematic
Post by: Wakutan on June 23, 2005, 12:31:20 AM

Oh yea another weird thing is:

I've lifted pin 107 up, so its not connected to +5V nor GND.

I've tested my MegaDrive 2, and it works normally on 50Hz like always.

Can someone explain? The pin 107 was just lifted up, thats all.

Title: Megadrive 2 50/60Hz MOD schematic
Post by: phreak97 on June 23, 2005, 12:44:39 AM

lifted it's left floating.. it's not at true ground, but the way the chip is, it takes that as being low, which is 50hz.. it's probably not a very stable way of doing it.. but itll probably work.. i had some saturns that were like that when i got them:/

Title: Megadrive 2 50/60Hz MOD schematic
Post by: Aidan on June 23, 2005, 03:12:34 AM

Whilst most people will talk about two states in logic circuits, there's actually three: High, Low and Hi-Z. Hi-Z is when the pin is not connected to either power or ground. It's usually used to ensure that multiple devices sharing the same wires can talk without causing chaos.

Most logic inputs expect either a high or a low. If you leave the pin 'floating', then it's in an indeterminate state. Depending on a number of factors, such as the internal design, what level of general background noise, what day of the week it is and what I had for breakfast the logic can interpret any stray signal in whatever way it feels like.

IE, it's a bad idea, because you might just find that sometimes it'll assume the wrong state!

Title: Megadrive 2 50/60Hz MOD schematic
Post by: Wakutan on June 23, 2005, 04:30:10 AM

Ok thanks for the info.

That means i need only a 3 pins throw switch, and i can select between 50Hz and 60Hz.

PAL50 and PAL60, right?

I am actually sick and tired of playing Megaman Wily Wars with terrible slow music.

Thanks again!

Title: Megadrive 2 50/60Hz MOD schematic
Post by: efkap on August 17, 2005, 06:59:45 PM

Hello,

maybe I'm wrong but I thought pin 107 affects only the language setting (jap/eng) and not the frequency (50/60Hz).

link to language mod (http://www.mikeg2.freeserve.co.uk/masterful/md2lang.html)
link to frequency mod (http://www.segaxtreme.net/misc/faqs_html/md2_switch/index.html)

Bye

Title: Megadrive 2 50/60Hz MOD schematic
Post by: -Martin- on August 22, 2005, 02:06:08 AM

I left the pin on my SMS II floating when I did the 50Hz/60Hz switch and it works fine; however on my saturn it constantly flicked between 50 and 60 Hertz

nfg.forums

NFG Forums => Console Mods => Topic started by: Wakutan on June 23, 2005, 12:24:22 AM