S-video mod on Genesis 1

[futureman2000]

**Solved, was a shit 3rd party power supply...**

First off, I'm aware that this is not the ideal place to pose this question- but I can't seem to get my membership at Sega-16 approved.  

I recently did an S-video mod on a Genesis 1, using this technique: http://www.jamma-nation-x.com/jammax/genesismods.html

I am having an issue with the video: there is a faint grainy/wavy bar which slowly moves up- it is about 1/5th the height of the screen. The affected area is just a bit unclear/ fuzzy. The effect (when used on my CRT) is very faint, to the point that I don't think that I could effectively capture it with a pic. When used on my flat screen, the fuzzy bit really took over, and made it look terrible.

Aside from this, the video looks excellent (on my CRT). Great color, very sharp. I don't really intend to use this on my HDTV anyway, was just testing it out...

There are a few things that I think could have caused this. I'm very much an amateur.
-I removed the RF shielding above and below the motherboard in order to fit in the mod wires. Information online seemed to indicate that this can be removed, but I'm not sure.
-The capacitor that I bought had the proper specs, but looks to be about 4x the size of the caps used in videos that I have seen.
-Poor soldering job somewhere?

I appeal to the expertise of the forum!  I could root around and fix the things listed above, but I'm wary of picking around too much... so that my stupid fingers don't do any damage.

TL/DR - there is a wavy/grainy bar that moves up my screen after S-video mod- Is there anything obvious that would cause such a thing?

Thanks!

[SignOfZeta]

Are you absolutely sure this bar isn't present from the standard composite output as well?

[futureman2000]

Nice, I didn't think to check that. I'll test it out when I get home.

[thesteve]

that sounds like a typical "hum bar"
check your grounds.
try replacing the power supply caps in the geny

[futureman2000]

Thanks for input guys, turns out it was a 3rd party power supply that was causing the hum bar. I've learned an important lesson today about using genuine video game products...

[SNKNostalgia]

Funny that I just did this mod to my Genesis 1 (second revision, blppppttth sound version). I used the original S-video mod that was used for the Neo Geo and Genesis over the years and then did the revision 3 days ago. Much nicer output with orange being orange instead of a pinkish yellow, which is a great example of this improved mod.

Xian Xi's revision doesn't even need a NT-85 transistor with a whole bunch of resisters and two caps for half the mod. It really cuts down on the cost and the output doesn't have that white flushing when stuff pops up on black backgrounds and the colors are a lot more accurate.

[futureman2000]

Do you have the version with the tiny CXA1145 chip? I believe that it is the last revision of the model 1, and it also has the worst sound. The smaller CXA chip is only accessible from the top side of the board, so you have to solder onto the tiny legs. Anyway, I aborted a mod on one of these but I will prolly revisit if you had success with it.

[SNKNostalgia]

Yes, it is that exact model. It isn't that hard to solder to the smaller CXA1145 actually. Just make sure you have a small solder point attached.

This reminds me that I need to get the "High Definition" version with the better sound and do this mod on it. Next time, I am buying a nicer S-video plug instead of using a scrap one from a video selector that died, lol.

Then again, I am actually considering on just buying a SCART RGB to Component convertor $50 and a SCART cable on E-bay for $12. This really would be the better option. As a major plus, I can also use it with my SNES, PS1, Saturn, Neo Geo CDZ and Dreamcast (for the 2D games that look better not using VGA). All my CRT sets have component, why not!?!?

[Frank_fjs]

The Mega Drive looks great via that setup, RGB -> Component that is. So does the Master System, here's a screen from my Master System going into the RGB-YUV encoder and displayed on a plasma:



Exact same setup via composite, just for reference:



Via RGB SCART on a CRT TV:

[futureman2000]

ugh this is the same dilemma that I was faced with. Had I properly thought through the cost of the s-video mods, I would have done the RGB -> Component. Then again, my game room CRT only does composite or S-video.. which is why I chose s-video. Screens look great, Frank... really breathes new life into the Master System (and Genesis). I did the same s-video mod on my master system, and it the result is just like on the Genesis. (Same chip, so duh? dunno.)

[SNKNostalgia]

The Mega Drive looks great via that setup, RGB -> Component that is. So does the Master System, here's a screen from my Master System going into the RGB-YUV encoder and displayed on a plasma:



Exact same setup via composite, just for reference:



Via RGB SCART on a CRT TV:

Yep, you can't go wrong with RGB to YUV unless of course you have a LCD/Plasma that doesn't want to work with a 240p component video output (Neo Geo AES being the worse offender due to the slightly off vertical refresh rate). Westinghouse HD sets comes to mind, which is what my parents have at their house... one being in my old room.

[Frank_fjs]

I've found that Samsung TV's also don't play nicely with a 240p signal.

I don't actually game on my plasma, I just wanted to test out the encoder and see how it would look. Aside from no scanlines it's pretty darn good. I would get one of those scanline generators like the SLG3000 but I'm not happy with the price of them and limited input/output - and I really don't want to tie one of those arcade encoders into the mix. I have one and aside from being occasionally useful, the picture quality is lacking.

So I just game on an RGB SCART enabled CRT, no fuss and the best results. I will be sad when there aren't any CRT's left though.

[thesteve]

the issue is 2 fold with newer/flat displays
1 the scaling is done through mpeg encoding and decoding in screen res (causes delay and artefacts)
2 240P was never oficially supported and not implemented except in PVM type displays