Alternative S-video mod for AES

shadowkn55

shadowkn55

Genbu's Turtle Keeper
15 Year Member
Joined
Dec 9, 2006
Posts
2,386
P00t

P00t

Fuck eBay & PayPal,
Joined
Jan 24, 2004
Posts
2,745
Thats for the Genesis/Megadrive man, not the AES.

Xian is the website owner by the way.
 
shadowkn55

shadowkn55

Genbu's Turtle Keeper
15 Year Member
Joined
Dec 9, 2006
Posts
2,386
It says on the page that it's also for the AES. Both systems are based on the same encoder chip so the mods should be fairly interchangeable.
 
P00t

P00t

Fuck eBay & PayPal,
Joined
Jan 24, 2004
Posts
2,745
xiao_haozi said:
... But if you are going to go through that trouble, my opinion would be just to go with a DIY s-video neobitz. Takes like 15 minutes to put one together and doesn't hit the wallet to hard.
Click to expand...

I was going to say the same thing, much less hassle to just buy a DIY kit from Jeff.
 
shadowkn55

shadowkn55

Genbu's Turtle Keeper
15 Year Member
Joined
Dec 9, 2006
Posts
2,386
I already did the mod that's based on the megamod and the picture looks fairly good. If Xian_Xi's mod works, it seems like it would be a lot easier to build and mounting wouldn't be as big an issue.
 
xiao_haozi

xiao_haozi

Avid Neo-Expert
Joined
Jan 22, 2009
Posts
1,977
shadowkn55 said:
I already did the mod that's based on the megamod and the picture looks fairly good. If Xian_Xi's mod works, it seems like it would be a lot easier to build and mounting wouldn't be as big an issue.
Click to expand...

True but I still think a DIY neobitz is the way to go with svideo. But that's just my preference.
 
Xian Xi

Xian Xi

JammaNationX,
15 Year Member
Joined
Dec 1, 2005
Posts
27,754
I've tested it and it works but for the AES I think the Neobitz which uses an AD724 works a lot better than the onboard Sony encoder.
 
Xian Xi

Xian Xi

JammaNationX,
15 Year Member
Joined
Dec 1, 2005
Posts
27,754
shadowkn55 said:
I just stumbled across this and was wondering if anyone has tried it out.

http://www.jamma-nation-x.com/jammax/genesismods.html

How does it compare to the other s-video mod for CXA1145 based systems?

http://gamesx.com/wiki/doku.php?id=av:genesis_1_s-video_mod

The schematic at jamma-nation-x doesn't quite look right either. It says the mod uses an NTE85 which is an NPN transistor but the picture is for a PNP transistor.
Click to expand...

Also, the schematic was done like that since the NTE85 has a different pinout than most of it's kind. In fact when I first did the other mod I followed what the picture said and it didn't work since the pinout for the NTE85 was different. The text on that schematic was very misleading. This way my picture would be easier to understand for the less experienced modders.

For the Genesis the chroma and luma signals are fed back into the encoder, I don't know if this is the main cause for the color bleeding but the circuit on my site does work better than the other more complicated mod. The circuit on my site was designed by vietlim from gamesx who said all the capacitors and resistors were "superfluous" which means not needed and it is true.

When I made my mod I actually used pots to adjust the chroma signal and when the signal was brought to 300ohm resistance then the bleeding was dramatically less than the original 33ohm. At 33ohm it was just yuck.

Same with the Mega Mod for the Neo, it has color bleeding as well.
 
MKL

MKL

Basara's Blade Keeper
20 Year Member
Joined
Mar 8, 2002
Posts
3,686
Xian Xi said:
Also, the schematic was done like that since the NTE85 has a different pinout than most of it's kind. In fact when I first did the other mod I followed what the picture said and it didn't work since the pinout for the NTE85 was different. The text on that schematic was very misleading. This way my picture would be easier to understand for the less experienced modders.
Click to expand...

The transistor symbol is universal and has nothing to do with how the legs of the physical component are laid out. It's not acceptable to use the symbol and label it incorrectly (labelling is not even required since the symbol is clear enough). If you want to make your schematics noob friendly I suggest you to replace the transistor symbol with a picture of the actual component. "Serious" schematics are only for those who can understand them.
 
werejag

werejag

Galford's Poppy Trainer
Joined
May 3, 2005
Posts
2,626
yeah that transistor on xx site is wrong

HERE IS THE SAME DIAGRAM DONE FROM A COMPONENT VIEW

chromalumaamp.jpg
 
Last edited:
MKL

MKL

Basara's Blade Keeper
20 Year Member
Joined
Mar 8, 2002
Posts
3,686
That's ambiguous as it's not clear if the transistor is viewed from the top or from the bottom.

This is what noobs want:

 
Xian Xi

Xian Xi

JammaNationX,
15 Year Member
Joined
Dec 1, 2005
Posts
27,754
Thanks guys. Michel I'll use that pic instead as it's more clear.
 
M

Monolith

Pleasure Goal
Joined
Jan 17, 2007
Posts
146
How does the picture quality on that mod you did compare to the one listed here?
http://www.smspower.org/forums/viewtopic.php?p=55425

I know someone who did that mod, that uses one 220 uF electrolytic capacitor in conjunction with a 75 ohm resistor on pin 15, and one 2N3904 transistor, and a 27 ohm resistor on pin 16. I think my friend used different values on the resistors to get the quality he wanted though.
 
Xian Xi

Xian Xi

JammaNationX,
15 Year Member
Joined
Dec 1, 2005
Posts
27,754
Monolith said:
How does the picture quality on that mod you did compare to the one listed here?
http://www.smspower.org/forums/viewtopic.php?p=55425

I know someone who did that mod, that uses one 220 uF electrolytic capacitor in conjunction with a 75 ohm resistor on pin 15, and one 2N3904 transistor, and a 27 ohm resistor on pin 16. I think my friend used different values on the resistors to get the quality he wanted though.
Click to expand...

With the CXA in the Genesis it takes some messing around to find what you like. Your friend's combo sounds like he was experiencing the same problems as me with the original circuit that was designed.
 
Xian Xi

Xian Xi

JammaNationX,
15 Year Member
Joined
Dec 1, 2005
Posts
27,754
Redid mine earlier today with a 220uf + 75ohm on the Chroma line and the NTE85 circuit on the Luma line and it is really nice looking on my Genesis 1. I think I'll try it on the Neo and see what I get.
 
shadowkn55

shadowkn55

Genbu's Turtle Keeper
15 Year Member
Joined
Dec 9, 2006
Posts
2,386
I'll be trying it out as well but on an mvs board instead. Thanks for your help everyone on clearing this up.

Edit:

I threw this together for those that prefer the schematic representation.

CXA1145S-VideoMod.png
 
Last edited:
Xian Xi

Xian Xi

JammaNationX,
15 Year Member
Joined
Dec 1, 2005
Posts
27,754
Make sure that on C1 you connect the negative lead to the chip and positive to the resistor.
 
shadowkn55

shadowkn55

Genbu's Turtle Keeper
15 Year Member
Joined
Dec 9, 2006
Posts
2,386
Fixed. Feel free to use it on your site if you want.

I tested it out and it looks pretty good. A lot simpler than the megamod.
 
shadowkn55

shadowkn55

Genbu's Turtle Keeper
15 Year Member
Joined
Dec 9, 2006
Posts
2,386
The polarity of the capacitor contradicts what Xian_Xi says. I've tried it the way XX mentioned and it works well. Haven't tried it with the polarity reversed though.
 
M

Monolith

Pleasure Goal
Joined
Jan 17, 2007
Posts
146
My friend said it did not seem to matter which way the capacitor was aimed, that it had no affect on the image quality either way it went when he did the mod. He said he tried it both ways a few times to make sure, so I wouldn't bother. If you are happy with the image quality you got then if it was me I would leave it that way.
 
Xian Xi

Xian Xi

JammaNationX,
15 Year Member
Joined
Dec 1, 2005
Posts
27,754
Ok was bored today so I decided to test out this s-vid mod on an AES I had lyning around.

Composite:
ss1comp.jpg


S-Video:
ss1svid.jpg
 
M

Monolith

Pleasure Goal
Joined
Jan 17, 2007
Posts
146
Did you have to tweak the values or anything, or did you do it as it is posted on the schematic shadowkn55 presented? It looks great,seriously.
 
You must log in or register to reply here.
Top