Megadrive does not boot up.

[keoni29]

I bought a faulty megadrive model 1 yesterday. I tested it with some games to see if it worked to some extend. Sonic2 and super battletank did not boot up, but themepark did show the logo animation, but no game. I noticed that pin 6 of the cpu was cut and lifted. There was a resistor put in between pin 6 and the trace which originally was connected to pin 6. I removed the resistor and resoldered pin 6 onto the trace. Same result when I put in those games. Any clue as ti what coild be wrong with this megadrive? The games all work on my megadrive2.

[YANDMAN]

This sounds like somebody has tried a possible region mod and maybe bodged it and given up

[keoni29]

The traces of the jumpers are not cut and I don't see anything strange other than the cut pin on the cpu. Is there some mechanism (read circuit) in the megadrive that stops it from booting up games? If so: something might have been broken on this mechanism and it will never boot up games. A region lock for example. The previous owner was probably messing with this mechanism to be able to play foreign games. He said he used the megadrive to test games before he sold them. He also said he played american games on it with no problem. I'm not sure if he managed to play region locked games.

[keoni29]

I find it strange that it's not possible to edit posts. I cleaned the cartridge connector using sandpaper, air and rubbing alcohol. Still no luck. The problem has to be something with the electronics. I have repaired other consoles, but this is my first megadrive model 1.

[keoni29]

I found out that the resistor on pin 6 of the cpu was put there in the factory, because this model had some flaws with the chipset causing the pin to overload. The result was a lot of freezing. I'm gonna put another resistor there probably with a slightly higher value and see what that does.

 

Source: http://nfggames.com/forum2/index.php?topic=4614.0

[keoni29]

I had this thing in storage for too long. Now I want to fix it. I tried adding some fresh solder to the CPU and the cartridge connector and some other IC's. I replaced a seemingly broken capacitor, but I get the same result everytime: a bright flash and then nothing. With themepark I get a flash followed by the EA logo, but nothing else.

[keoni29]

I thought everything had to do with the CPU or TMSS. After hours of research and fixing potential causes for the problem I found out the the RF modulator was broken. I found a thread on a forum where some guy suggested to plug in earphones to check for sound. So I plopped in Sonic2 and heavens choirs chant "SEGA". Boom! It's just a video issue. It was weird that Themepark showed the EA logo just fine. This put me on the wrong trail. So I made myself an AV cable and I got video. I played trough act 1 of sonic and I could not spot any issues. It worked all the time (except for the RF which I don't need)