7800 Video Mod advice requested

[SINGLE TOOTH]

Ok, so I modded the 7800 for a/v out according to the F.A.Q. When I booted up the system with Pole Position II, there is no white. Every other color is there, but I have no white?

 

White is the Luminence, Correct?

 

I tore the wires off from the circuit to the 7800 and resoldered them back on, but same results.

 

I went over the circuit once, but im going to go over it again.

 

Any suggestions?

 

When I put a 2600 game in, it looks a little dark, but the colors are right.

 

Maybe the 7800 FAQ has errors, The 5200 Faq has the chroma in the wrong spot.

 

 

**update**

I took the 7800 Chroma lead off the circuit, and the picture looks good except its black and white.. The "prepare to qualify" blimp would be white with black text.

When I reconnect the chroma, the blimp turns black with white text.

 

I dont get it.

 

Im using the method found Here.

Edited June 14, 2007 by SINGLE TOOTH

[Rybags]

No white?

 

What do you mean - no shades of grey either, or just no bright whites?

 

If there's only greys but no white, I'd guess that the luminence needs attenuating, ie - a bigger resistor value.

[SINGLE TOOTH]

its kinda hard to describe...

 

 

It seems when I hook the Chroma up, all the luminance dissapears. When the chroma is disconnected, there is a nice picture that is monochrome. everything seems to be as it should until the chroma is connected. then the bright whites seem to dissapear. And when the blimp goes by the colours on the blimp seem to be inversed. The blues, greens and etc are correct, though.

[Rybags]

Maybe put a trimpot inline with the Chroma.

 

There's a recent thread where someone did the mod but used a mix of advice from a few existing ones - probably worth digging it up.

 

I'm planning to add A/V to my 7800 as well soon - the TV out from mine is abysmal, not helped one bit from the fact that the jack seems to be very worn.

[SINGLE TOOTH]

Maybe put a trimpot inline with the Chroma.

 

There's a recent thread where someone did the mod but used a mix of advice from a few existing ones - probably worth digging it up.

 

I'm planning to add A/V to my 7800 as well soon - the TV out from mine is abysmal, not helped one bit from the fact that the jack seems to be very worn.

 

I was thinking about putting a trimpot in, until I saw that the certain colors got reversed. I'll try it out anyway, anything is worth a shot.

 

Ill have to take a pic of the TV screen, so you can see for your self what I am talking about. It's just too weird to not see.