MX7000 missing red color when using RGB

I have a MX7000 SW version 4.5. and an Original Xbox connected to AV2 using an official Microsoft Advanced Scart cable. AV2 is set to decoder and I have tuned a channel to show to scart input. I'm using this method so the service menu is available and I can tweak geometry and colors.

Now it seems that when RGB is used in this situation the screen does not output any reds, only blues and greens. When I connect the Xbox to the same AV1 using a composite cable, I do get all normal picture. When I enter the menu while in RGB mode, the output automatically switches to composite (i think) and the colors are normal, plus the picture/service mode settings are applied.

When connected to AV1 set to DVD, the colors are normal, but im not sure if its using RGB or composite, as the picture quality is the same as in the above situation in the menu.

I've opened up the back and overall, the unit is in very good condition, dustfree and without any visual damage to capacitors or the boards.

Now my question: Could this be a hardware issue, where to look if so? Or am I doing something dumb and this is expected behaviour when connecting an RGB signal to AV2 set to decoder and I should just use AV1 set to DVD?

 

Hi - someone more technical may comment on the TV.

I would check first that you have continuity on all 21 wires of the cable. Not all cable manufacturers wired all 21 pins.

Thank you for your answer. I cant see to get the multimeter to work with these small pins on the xbox cable.

There a Playstation 2 RGB scart cable coming my way, if that does not show the same symptoms it must be the cable or xbox.

The PS2 RGB cable image was perfect, so I opened up the XBOX RGB cable, and what do you know.... The red wire connection was broken! Easy fix :)