5200 AV mod- no color?

[Manta]

I've just converted my 5200 to use AV (with the plan to completely remove the RF vable and mount a power jack directly into 5200 via a choke to block RF signal)

 

After futzing around with the mod I was able to get picture and sound but there's no color! I've rechecked the connection. The wire for chroma goes to the next to last resistor on the mainboard, is fed through a 2K resistor and 1uF capacitor before going to the Luma line for composite output. I don't have any means of checking separate video, only composite.

 

Is there something on the 5200 board that would need to be tweaked? The only other possibility was a bad cap but I don't have a cap tester.

[CPUWIZ]

Which instructions did you use and which model is it (2 or 4 port) ? I am just curious because I had some trouble with a 2 port myself.

[IceCold]

Which instructions did you use and which model is it (2 or 4 port) ? I am just curious because I had some trouble with a 2 port myself.

 

CPUWIZ have trouble with something????? that has GOT to be a typo

[Manta]

4 ports, and the serial number has a star (*) in it. The instruction I used is the common 5200 FAQ including the one right here at Atariage.com

 

The synch and the correct brightnes sshows I have the luma correct and there's audio. I desoldered and removed he entire RF modulator (5 pins and 3 ground point for the shield box) and I got *some* color but it's weak. I checked the schematic and found the variable resistor just to the right of the power LED is used in color delay, adjusting it had little improvement.

 

Maybe the chroma output needs its own amp? The luma did need one. I'd like to get this solved before I try the 7800 mod and whittle away one less RF based console. (next is Colecovision and Intellivision and then I can finally ditch the 5 ports RF switch box and directly hook up the satellite and antenna to it)