Neo Geo Composite Video

[Segasonicfan]

I was looking over the site and saw this.  So the Neo Geo Composite out is poor....but I have a hard time understanding why.  My Neo Geo CD also outputs terrible Composite but it uses a CXA1645 chroma encoder.  So how can the Composite video be bad with a good chroma encoder (and seemingly) perfect RGB output?  Just curious as to what I'm missing...

-Segasonicfan

[Aidan]

All the bits that are needed to support the encoder? A good encoder on it's own does not equal a good output. Every component involved in the processing (including the PCB!) has to be well specified or designed.

You can take the best encoder in the world and hook it up with poor components and a poor PCB layout and it will suck.

[viletim!]

Noise from power supply, feeding the IC with wrong signal levels, off frequency colour oscilator, and other stuff like that. Maybe it's just a poor design... What do you mean when you say the quality is terrible?

[kendrick]

SSFan is referring to the NFG chart that describes poor composite output from certain revisions of the AES home console. Either you have bright color and poor clarity, or sharp picture with washed-out color, or some unacceptable mode in between. I think that Aidan is on the money with his analysis, if you consider that SNK didn't really do much more than slap an early version of the MVS board into a plastic case with little consideration as to how people might want to use the thing. Since it was adapted from arcade hardware and not designed from the ground up to be a home console, I'm not surprised that there's a great deal of compromise in the components that adversely affects the output. It's not a wonder that the Neo AES is such a popular target for modding.

Truthfully, it doesn't make much of a difference to my old eyes. The hardcore among us will already be pulling S-video and RGB output from all our hardware, so the quality of the composite output should really be of no importance.

-KKC, resisting the urge to shop.

[XianXi]

The only difference I noticed with my Neo after I modded it is when I use component the lines are sharper and the color is more vivid than the composite video.

[Guest]

actually, i was not referring to the AES output. I have a Neo Geo CD.  The quality is poor with the rainbow color effect seen in whites and thin light lines.  It's really bad.  The output is great with S-video though.  Thanks for clearnin up the chroma encoder design as the posible flaw....I'll try putting in other components/redesigning it.  They did use incredibly cheap components in the Neo Geo CD.

The only reason I care about composite video quality is b/c I like to bring my system to my friends house to play fighters and whatnot together.  He doesn't have S-Video inputs.

-Segasonicfan

[NFG]

The rainbow effect is a byproduct of composite video.  You can't get rid of it.  Most systems suffer it under the right circumstances.

The NeoCD was very, very well built.  Except for the CD mechanism itself it's better quality than most other consoles.

[Segasonicfan]

Yes, but the rainbow effect is far worse in my Neo Geo CD than say, Genesis or any other system with composite out. Has anyone else noticed this?

The NeoCD was very, very well built

Are you being sarcastic?  The NGCD is a monstrosity unworthy of its original selling price.  Look at the CDX-released the same year, at the same price point ($300).  The CDX incorporates a built-in DC-DC converter, a "click" disc holder (like what modern CD players use), two tri-layer PCB boards and it uses pretty much all surface mount components of the smallest available size of the time.

The NGCD on the other hand, uses one-sided controller and power PCBs, 2 entirely unecessary 7805 regs (when it has a 5v input?!?), 2 other regs (all of which aren't even heatsinked), the two top boards also use REALLY cheap components...I mean the CXA1645 is a DIP and all the caps are the cheapest largest possible (the resistors too).  Appearently SNK made no attempt to make this system any smaller...thus it has the approx size of an XBox.

Don't get me wrong, I LOVE the NGCD (my new fav system), I just don't think it's well built from a hardware perspective.  

[NFG]

So what you're saying is size = quality?  Aside from your interesting comment about 'unecessary' regulators, you haven't said anything but "it's big".  So what?

[Segasonicfan]

not just unecessary regs- poor heatsinking.  Actually there isn't any heatsink for any of the regs.  they are literally screwed onto the PCB.... :/

-Segasonicfan

[Aidan]

If there's a copper plane behind the tabs where they're attached, that's called heatsinking. Most PC motherboards use this to keep the high side and low side FETS cool on the CPU voltage regulator.

As far as the "unnecessary" 5v regulators - what's the input actually from? If it's from a standard unregulated wallwart, then the voltage will be higher than 5V when there's anything below the maximum load.

[NFG]

All the extra components and exceptional build quality point, IMHO, to a higher quality unit.  The Neo CD is nigh indestructible, not counting the CD mech.

If you want to see poor quality, investigate an Aiwa MegaDrive.  Those are complete ASS inside.  Covered in hot glue, wires everywhere, copper coils wrapped around sponges leaning at all kinds of angles...

[Segasonicfan]

If you want to see poor quality, investigate an Aiwa MegaDrive

Really?  I always wanted one of those... =(   The MegaJet is pretty good quality though, right?

-Segasonicfan

[NFG]

The MegaJet is made by Sega, it's quite nice inside.

[XianXi]

not just unecessary regs- poor heatsinking.  Actually there isn't any heatsink for any of the regs.  they are literally screwed onto the PCB.... :/

-Segasonicfan

The NGCD didn't have any heating problems, the CDZ did.