Genesis SCART interference pattern

I've mentioned this to a few people, but I thought I ought to make a thread about it as well. I've been having an issue with my Genesis using RGB SCART: I'm getting an interference pattern that looks like a wavy bar that travels up the screen. I've done copious testing and I've learned a few things about it:

1. I thought the problem might be my SCART to BNC adapter that I was using for my PVM. I was also seeing a similar pattern with some other consoles. So I built an entire new cable, just to be sure. With the new cable, all of my other consoles display flawlessly - no trace of the interference pattern. However, the Genesis interference pattern is still there. So I can rule out the adapter being the cause. I'm not entirely sure why I was seeing interference with the other consoles before, though I suspect it might have been just a loose connection. The Genesis shows the pattern regardless of the connection, however.

2. Next I thought maybe the Genesis SCART cable was the issue. I bought another cable, just to be sure. It shows the same pattern, though somewhat less severe. I didn't know what to make of this.

3. I'm using a model 1 to model 2 AV adapter in addition to the SCART cable. I tried swapping this with another one, and it appeared to lessen (though not eliminate altogether) the pattern. However, after some more testing, it seems it doesn't make much of a difference which adapter I use. The severity of the interference seems to vary somewhat independent of all the above factors.

4. Finally, I concluded (I thought) that there must be a problem with the Genesis itself. To test this theory, I used the same cable with another model 2 (my main Genesis is a model 1). Result? The model 2 shows the same interference pattern, though somewhat less severe. Again, it seems to vary somewhat on its own. This is odd...

So, after all this testing, what can I conclude? The SCART to BNC adapter is clearly not the problem, nor is my display, since all of my other consoles display perfectly. I also don't believe (though I can't be certain) that the model 1 to model 2 AV adaptor is the problem. This leaves 2 possibilities: either both the Genesis consoles I tested are defective, or both of the cables are defective. Neither of those options seem very likely to me, which makes me think I must be missing something. I have a couple other Genesis consoles I can test, so I suppose that's the next step. I could also buy another cable, but I don't feel like shelling out the cash for a third cable, especially when I'm not totally convinced that it's the problem. I've taken apart the SCART end of the new cable, and everything looks as it should. I don't know of a way to look at the Genesis end without breaking the cover, so I'm going to hold off on doing that for the moment. One important thing to note is that this is a new problem - prior to a month or so ago, the video output of the Genesis was just fine.

Can anyone make sense of all this? It doesn't make much sense to me.

 

Have you tried using c-sync instead of composite for the rgb sync?
I was having some wavy pattern on both md1/sms1 and c-sync fixed this ...
here is info on how to mod the system for c-sync: http://www.mmmonkey.co.uk/console/sega/md-sync.htm

here are pics with the issue I had:

before (notice the wavy lines)


after modification:

 

That is a possibility, although I have some other consoles that use composite video for sync and they work fine. It might be worth a try, but I would probably need someone else to do the mod for me. I think it's beyond my abilities.

It would be nice to have a switch for composite video and C-sync, so I could always use it with a standard NTSC TV if I wanted to.

 

AFAIK this "wavy" effect is because of the SONY CXA rgb encoder that both md1/sms1 (at least) use... it's not a composite problem strictly... a switch is easy, one common pin and 2 more, one for c-sync and one for composite

 

this is what i have done with my model 1 works nicely

 

I guess that's possible, but like I said, it's a recent problem. Prior to a few weeks ago I saw no interference at all.

UPDATE: The interference pattern is gone. I just connected my Nomad to test the video signal, and it lacked the pattern, and then I tried the model 1, and it lacked the pattern as well. Maybe another device in my setup was messing with the signal? I have a lot of devices plugged into one power outlet, so perhaps noise from the various AC adapters somehow seeped into the video signal. Strange.

 

just a thought, but have you tried replacing the capacitors if this is only a recent issue then maybe they're starting to dry up, can't hurt seeing as they're probably pretty old anyway 20+ years

 

UPDATE 2: Aha! I've found the culprit. I turns out my Wondermega AC adapter is causing the issue. I discovered it by coincidence. I was testing the model 1 Genesis, and I noticed that the interference pattern was gone. Huh, I thought, I wonder why that is. Then, for no particular reason, I decided to power up my Wondermega. I noticed that the power supply was unplugged, so I plugged it back in. It powered on and was operating normally. Then I decided to power on my Genesis again, and guess what happens? The interference pattern is back. So, I made the logical connection and decided that having the Wondermega plugged in - it doesn't even matter if it's powered on or not - is causing the interference. Sure enough, I can see it happening in real time - when I plug the Wondermega in, the interference appears. When I remove it, it disappears. Couldn't get much more straightforward than that.

As far as why this is happening, I have no idea. Maybe a person with more knowledge about electrical wiring could explain that. I suspect that either the Wondermega PSU is defective (it's a cheap Chinese third-party unit), or it's simply due to having too many devices plugged in at the same time. Oddly enough, it doesn't affect any of the other consoles I have set up - just the Genesis. Anyway, that solves that mystery. I hope this experience can be helpful to someone.

FINAL NOTE: This issue occurs even on my Nomad, which is running on battery power and not connected to any external power source. So somehow the PSU is causing interference on the video lead itself. Like I said, it affects only the Genesis, so I know it's not directly affecting my PVM. Perhaps the PSU is not shielded properly, and thus is leaking electromagnetic radiation, which for some reason affects only the Genesis lead.

 

You shouldn't leave devices plugged in when they're not in use, anyway. Not only can it cause interference but it costs you money. That, and there were some devices with dodgy PSUs that overheated.

If you're using an extension bar, get a decent one that's individually switched.

 

That's totally unrealistic. Should I unplug my TV when I'm not using it? Or my router? AC adapters of the kind that power game consoles use a tiny amount of power when not in use. It's reasonable not to leave devices plugged in when you leave your house for an extended period of time, or when you're not using a particular device very often. But I can't see how you could possibly think that it would be acceptable to leave every single electronic device in your house unplugged except when you're currently using it. Read that sentence one more time and really think about it.

 

Switched off at the plug is the same as unplugged.

Its not completely unreasonable really. I have a 8 way extension that is timed, you press a button (thats on a wire and you can position outside of your AV rack) and it will be on for 12 hours.

If you dont care about waste, then just replace the psu

 

Are you using some SCART switch box for Wondermega Nomad and Genesis?

 

How is that unreasonable? Plug common devices into an extension. When you finish with them, SWITCH THEM OFF. It's not unrealistic, not doing it is PLAIN LAZY.

True story: my friend is a stickler for turning off devices. He turns off his whole computer system - yes, even his router. Television system, including stereo. It's a mere flick of a switch to turn back on. His house was hit by lightning this year. It blew all his electrical devices up. 42" Television, computer, Bose stereo, high tech shower unit with TV - gone. They were all plugged in but switched off. Conversely, his kitchen appliances were OK as they were unplugged. So no, switched off at the plug is NOT the same as unplugged if you care about your devices. Oh yeah, and it knocked out his entire solar system - not just the panels but the main unit.

Also, watch this:

http://www.youtube.com/watch?v=nVEQf2x9clo

They actually build those into some televisions now. Plus the original device is available, of course.

Oh, and read this:

http://www.thisismoney.co.uk/money/...-cost-leave-household-appliances-standby.html

Yes, it IS a lot of waste, it's costing you money. So it's up to you. If you don't mind wasting money and contributing to the whole energy crisis/global warming issue and don't care if your devices blow up, continue being ignorant.

 

i agree with Mr Retro, although do not currently follow said advice on the grounds that i'm lazy, but probably should, i dont bother switching off the power to my pc and related devices as they are used pretty much daily, but other things i probably should. i need to invest in some more switchable extensions and individually switching power strips. relocating them so they are easily accessible

 

I'm sure we've all been guilty of a bit of laziness when it comes to devices being plugged in... you just have to ask yourself if you'd be upset if it blew up, though!

Yup, switched extensions for devices you use a lot - very handy for consoles as you don't need more than one actually plugged in at once. Great if your sockets are hidden behind a unit, too - as you can have it under the unit or whatever. Unplug the extension when not in use if you value your items, though - lightning strikes and power surges may be rare, but it could happen!

 

Nope, no switch box. I manually switch the SCART cables for each console. Plus, the Wondermega doesn't even support RGB - I'm using S-Video for it.

EDIT: Removed long, pointless argument.

 

Note: looking back on this now, I don't know why I made such a big deal about the power consumption thing or why I did such a big writeup about it. It's really not all that important to me, and I think you're (retro) basically right - it's just not a change I'm willing to make in my own life. I sometimes get upset about things for no good reason, especially on the internet. So I'm sorry about that.

Back on topic: for the moment, I'm leaving the Wondermega unplugged until such a point as I find a better replacement or build a switch for it.

 

Remember to retain context, it's important in discussions. We were talking power usage and interference. Throwing new variables into the mix is cheating.

 

Noooo! That's what the Internet is for!

Lol, no problem. Hopefully some people might understand from our conversation that unplugging (or switching off) will save you money and what have you, at least. For you, it might be worth getting a Standby Saver, though - it just cuts power when the TV is off, essentially. I can't remember offhand, but I think the point was that TV off = you're not using anything else plugged in, so they all go off.

I find it amusing that you're unwilling to unplug your devices, but you'll fiddle around behind your TV each time to plug one into the SCART! Well, you're in the US so maybe you don't have SCART on the back of the device like we do.

You could get a third party PSU for the Wondermega, or maybe your SCART adapter needs screening?

It's more a case of common sense than anything. Yes, switching off and leaving the extension plugged in will be fine for anything other than a power surge or lightning strike, and I mentioned switched extensions. He came back that it's crazy to unplug your television, so I explained why it's not only costing money and potentially dangerous if something melts, but there's a further risk. Elaboration, not cheating