7800 color saturation adjustment?

[Underball]

So I did the "easier composite video mod" for my NTSC 7800, and although it looks crisp and tight, I'm kind of disappointed with color saturation.

 

The issue is that R11 was replaced with a 100k potentiometer, which allows for luma adjustment. You can cut out 90% of the NTSC artifacting/ghosting, but the more you tune out ghosting, the less saturated the color output becomes.

 

Is there somewhere else on the 7800 mobo that a color saturation adjustment can be done?

 

Also - can the red/green tint adjustment be done on the 7800 Motherboard as well, instead of on the TV?

 

Thanks.

[robertski]

So I did the "easier composite video mod" for my NTSC 7800, and although it looks crisp and tight, I'm kind of disappointed with color saturation.

 

The issue is that R11 was replaced with a 100k potentiometer, which allows for luma adjustment. You can cut out 90% of the NTSC artifacting/ghosting, but the more you tune out ghosting, the less saturated the color output becomes.

 

Is there somewhere else on the 7800 mobo that a color saturation adjustment can be done?

 

Also - can the red/green tint adjustment be done on the 7800 Motherboard as well, instead of on the TV?

 

Thanks.

 

I did the mod also. I followed some advice in that thread and placed

a 10K pot on R16, which clears up all of the issues. I placed

the pots so they can be accessed outside the unit/

 

I believe some mods dont work as well due to the

inconsistancy of transistors, etc.

 

But, mine works fine. I also have a Sima Go-Video, I run it through

to adjust brightness, It has a LO and A BRIGHT setting, and an Radio

Shack Color image enhancer, which I lower the Bursat signal on

which makes the image real clean.

 

Its like christmas all year long....

 

Hope yours works out.

Rob,

[Longhorn Engineer]

So I did the "easier composite video mod" for my NTSC 7800, and although it looks crisp and tight, I'm kind of disappointed with color saturation.

 

The issue is that R11 was replaced with a 100k potentiometer, which allows for luma adjustment. You can cut out 90% of the NTSC artifacting/ghosting, but the more you tune out ghosting, the less saturated the color output becomes.

 

Is there somewhere else on the 7800 mobo that a color saturation adjustment can be done?

 

Also - can the red/green tint adjustment be done on the 7800 Motherboard as well, instead of on the TV?

 

Thanks.

 

Well the 7800 passes the chroma through a inductor and capacitor to phase the chroma a bit so the timing between the luma and chroma is close. This really messes with the saturation however.