Repair | Sega Megadrive II Famiclone??
A few weeks ago I was given this FAMICOM clone that looks exactly like a SEGA Genesis/Mega Drive model 2.
The thing only had RF output, so I had to drag out my old RF-only tv and hook it up….just a grey screen with some darker grey blocks over the screen.
Cleaning both the cartridge slot and the cartridge didn’t change anything, so I decided to open up the thing.
First thing I noticed when opening it up, was the rust on the screws.
That didn’t predict anything good.
Inside I found a lot of rust on the pcb’s and on the main pcb (containing the NOAC) the rust ate it’s way through some traces…..SHOOT!!
I was bummed for a brief moment there, but I recalled having a NOAC pcb in my parts bin and started digging……FOUND IT!!!
Since I didn’t have any documentation on this board, I had to reverse engineer the board and think of a way to interface it with the rest of the pcb’s that were in the MD2 shell.
So I took my multimeter and started looking for the +5V and GND pins on the board.
Those were found pretty fast by just looking up the famicom cartridge slot and looking at where +5V and GND from the slot went to a general pins on the board.
With those found, I took a USB cable which I chopped up and a tablet charger (+5V @ 2A) and soldered the cable to the board.
I inserted a famicom cartridge, hooked up another ground wire to a speaker and from there on it was a quest looking for the audio output pin.
I powered up the board with the usb cable and started looking for the audio output pin.
This only took me about a minute or so, but the NOAC board was working and I could hear the title screen music of the game I had inserted coming from my speaker!
I was excited as sh*t, because now I actually had the chance to repair this MD2 looking nes clone!
Now I had to find a way to hook up the board to a tv, and I did this by getting a donor AV board from my parts bin, but with all connections from the board to the cinch jack disconnected.
Then it was time to find the pin for video output.
This took a bit more effort, but I managed to find it.
As expected, the video signal coming from the board was too weak, so I had to amplify the signal.
I looked at some video amp schematics, but eventually decided to design and build my own.
It took quite some time, but by the end of friday night (12th June 2015) I managed to get a nice crisp video signal.
As you can see in the image above, the video signal was a bit too bright so I altered my video amplifier a little and since yesterday I am completely satisfied with my video signal.
See the images below for my final result.
Look at how nice and crips the text is right now 🙂
So now I need to reverse engineer the board some more and find the right pins for hooking up the controllers.
To be continued….