My Megadrive freezes

[cleeg]

It sounds to me (not any kind of an expert) to be the MD. If you have two carts that display similar faults the console is the common denominator. My MED plays well on all my MDs, Nomads etc. My suggestion would be try one more regular, cheap standard MD cart, if no joy consider buying a new MD console.

I hope you get this sorted, things like this can be maddening.

[aha2940]

My Sega Genesis had a similar issue. It turned out the CPU was bad (it was a Signetics IIRC). I bought another CPU chip on eBay, this time Hitachi-branded and replaced it. No more crashes. It was not easy to replace it though, many pins to unsolder and solder again.

Regards.

[wrx884]

I haven't this kind of material

But it seems the console is not the problem : I brought it to the retro-shop where he tested it with its own power supply and it worked like a charm for hours. So I bought another power supply and tested it at home : it works perfectly with Sonic 1 catridge, but it still crashes with the Mega Everdrive.

So I need to check the Mega Everdrive like said above. But I'm still stuck with the screws to open the catridge. It's a regular catridge (the screws are the same than the one of Sonic 1). What do you exactly need to open this ? I don't find something suitable at the tool shops near my home, it seems specialized.

To rule out its the mega ever drive give it to that retro shop and get them to play it for hours on their own consoles and then again on urs. If its the cart it will do the same thing on their consoles, if it doesn't then u know its more ur console.

What power supply are u using, is it an OEM power supply?? interesting his worked (was his genuine or third party?) and urs wouldn't as such but if that's the case it could still even be the voltage regulators but u wont know this unless u test them.

Try rule out the cart first.

[tryphon]

I gave my Med to the shop and he said it worked fine (when I came back to the shop, the console had freezed, but it's not relevant because he launched a ROM I wrote, and it's likely the freeze come from the ROM ; to be sure I launched a Sonic Rom and came back one hour later, it was still running ; it never lasted so long at home).

A strange thing : it seemed to me that the image was slightly shaking. I didn't notice it when it was playing the regular Sonic 1 cart.

So I bet it's the MD.

My old power supply was the original (the big thing, SEGA is written on), the new one is a 3rd party (labeled 'Power Adaptator for SNES' ! But the box said SNES and MD )

[Barone]

My thoughts on the issue, tryphon:
- The original PSU probably worn out quite some time ago and ended up compromising the capacitors of your MD.
- Changing the PSU probably fixed the first problem but not the other one.
- Your MD capacitors are overheating and under-delivering.
- Mega Everdrive consumes quite more power than a regular cartridge, so it will be likely to make your MD freeze sooner and more often than with a regular card (even if running the same game on MED).
- Games like Sonic 1 and Sonic 2 use on-the-fly decompression, so I think they'll be likely to put more strain on the cartridge slot circuit than a game which only access the RAM for content during its actual gameplay.
- Real carts of Virtua Racing, Sonic 3 & Knuckles (using the lock-on) and Super Street Fighter II also have power consumption higher than normal AFAIK (I listed them in decreasing order). But the MED, especially the first model, still consumes noticeably more power than those carts AFAIK.
- My suggestion: find someone to recap your MD prior trying to mess with the MED circuit. Image shaking is no good.

[tryphon]

Thanks a lot Barone for your detailed answer. I'm sorry I didn't notice your answer sooner (it was pointed to me in a thread I made on Krikzz board).