(Sega) Wondermega S-video interference question + Bonus MD 1 Quirk

Hello Assembler community. I guess I'm new; but I am familiar enough with these boards to get the sense that there are a number of members here who are somewhat accustomed to working with the Wondermega consoles.

So, I've owned an original Sega Wondermega for over a year now, and initially I was really concerned by its running temperature, which is to say, how hot it gets along the left edge of the console when using the original A/C adapter. In reading through another thread on these boards about the Wondermega, and in a few other places around the net, it appears this is somewhat normal; so I haven't thought as much of it, though I have wondered if it was at least exacerbating the issue that I've always had with the S-video output. I've since started using a PS2 A/C adapter from my JP slim unit, which actually seems to cut down the heat given off by the console somewhere in the vicinity of 75%, which is nice. However, I still get tons of static noise, and interference from the s-video output through an XRGB mini. I even notice some rainbow banding in text, etc. (Although, there was probably more apparent noise, and much more apparent rainbow banding, when I used the console on a CRT television.) The noise is most clearly visible in solid backgrounds (blues, greens, reds) but it's noticeable in smaller areas of certain colors, as well. What has really prompted me to action is what happened when I played around a bit with Sonic 2: All of the colors were wrong. The red bar in the stage intro screen was a fluorescent pink hue at one point, for instance; but it didn't really stay that way. As I progressed through stages it would actually fluctuate between proper colors, and drab, washed out colors. I've never really seen this happen with any other game I've tried on the console. The severity of the noise and rainbow banding has always seemed to worsen the longer the console is on, though.

The curious thing is that none of these artifacts appear (aside from some rainbow banding in things like the river in the opening stage of Robo Aleste, etc) when outputting composite directly to my LCD television. Is this just a quirk of the S-video from the Wondermegas? My gut tells me it's probably some bad capacitors, but getting that deep into the console is a nightmare. Is there a diagram for the capacitors on the Wondermega, like for the PCE DUO, at all?

I appreciate any input. I'm mainly curious if I'm the only one who gets this kind of s-video from the console or not; and I'm hoping someone might be able to point me in the direction of some good repair resources, if I am.


Thanks in advance for any insight. Hopefully I'm not breaking every forum rule in one fell post.

 

That's utterly ridiculous, it sounds more like you have capacitor issues considering the model 1 MD/Genesis has issues with dried-out or dying caps.

 

The Genesis is constantly outputting composite, S-Video, and RGB regardless of what cable you're using. As for how intensive a game actually is to the hardware I'm not sure since I'm not aware of any way to see how utilized the CPU/VDP is during operations.Sw

Swap the caps like ApolloBoy said. The damn things are bad and if they're not they will be soon. If any issues persist come back and there may be secondary ideas.

 

I mean, that's nice and all, but the caps on the MD board don't show any signs of leaking, or even puffiness. Ridiculous though it may be, what seems ridiculous to me is that capacitors would affect three specific games, and nothing else. I have zero issues with the console outside of trying to play those three games on it for an extended period of time. I suppose I was mainly curious if anyone knew of a board revision incompatibility, or something similar. I guess I could test the caps, but honestly, I'm not that concerned about it, nor am I interested in going on a wild goose chase over three games that, as I've said, I'm able to play through perfectly fine on the Wondermega. Though, again, I am concerned about the noise in the Wondermega video output; So I would love to have a diagram for its capacitors if one exists. Otherwise, I imagine I'll just have to go it alone.

 

I have a Victor Wondermega RG-M1, and I've never had problems with interference on S-video. The S-video signal looks really good, actually. However, I've actually had the opposite issue - I discovered that having the power adapter connected to the Wondermega was causing interference on the RGB leads on the other consoles I had connected to that setup. I wasn't using the original PSU, I was using a PSU for a netbook. It seemed to be working fine, but that must be what was causing the interference. I guess I need to get another PSU, but I'm not sure what would be ideal besides the original one (which I've lost, and wasn't working to begin with).

 

Just because they don't appear to be bad doesn't mean that they haven't gone bad. I've recapped a number of model 1s and it really isn't uncommon for the caps to die out.

 

It's actually very, very easy to tell when a Mega Drive is having capacitor issues. It has more noise on the sound. If you never used a Mega Drive back in the early 90s you can't really have a good reference of how it was supposed to sound and might think it was actually noisy like that originally.

Not quite.

SEGA hardware has a solid history of bad capacitors. Even the nice blue Rubycon caps I had on my 1990 Mega Drive I had to replace at some point.