Weak colours on my SuperGun

[Vertigo]

The colours output from my SuperGun are gradually but noticably fading, they're nowhere near as bright as they used to be and now reds are turning to browns, greens are fading to pukey yellows, and blues are almost non-existent.
Obviously I'd like to restore it to its former glory.
It does this with all boards so I know it's not them, and my TV does RGB fine with everything else so it's definitely the SuperGun that's doing it.
Anyone got any idea what I should be doing here to get my lovely colours back?

[Aidan]

Something in the supergun is dying perhaps? If there's any buffering on the RGB lines, a sagging power supply can cause the buffers to perform poorly. Capacitors drying out can have similar effects.

[Vertigo]

There's no buffering, it just runs straight through. Can't remember if there are caps in there. I'll open it up tonight and reflow everything and have a good smell of it all and see if anything's burning out coz I need to rewire the kick button interface anyway coz they're in a non-logical shit order. I kept meaning to check the voltages on my lines in there too, so tonight's as good a time as any. It could well just be one poor colour signal that's knocking everything else out, coz the picture is gradually getting very yellow and browny, so that looks to me like a red problem.

[NFG]

I have never seen color shift like you describe in an RGB signal.  Are you sure you are not using a chroma encoder?  You forget a lot of things, maybe you just forgot about the encoder.

[Vertigo]

I'll open it up and take a pic later. There is no chroma encoder. The colours are fading I think due to a weakened red signal, like I say strong vibrant reds are now turning into browns.

[Vertigo]

Pic of the inside of my super gun, don't point out the massive horror of it all, I'm well aware of that.

Click here

You have there in the top left a fan which was part of the ATX PSU in the top right that I cannibalised bottom left is the wiring which is just a PCB board with traces to connect everything together with the controller ports on top and bottom right is just the power and credit switches.
There's no chroma encoder or any of that shit going on, this is a direct RGB signal into a SCART lead.
Any more ideas?
I could take a pic of the brownness but it's hard to get a decent picture to look at out of an interlaced display.

[Aidan]

If there's nothing between the board and TV but wiring, then you either had a poor connection somewhere or the issue isn't with the SuperGun. If you have a multimeter check to see what the resistance between the board and the TV connectors is on the RGB lines.  

[Vertigo]

OK, I think I've sussed what this is.

Playing it yesterday for a bit it seems that when a screen fades in or out, the very brightest bit i.e. the gameplay screen that it fades to and from is where the colours are distorted, the very first frame of fade-to-black the colours appear perfectly correctly. This says to me that the output is over-bright. Do I need some resistors on the colour lines? If so, what strength do you recommend as a good base point to experiment from?

[DaveJ-UK]

I had a similar problem with one of my arcade monitors. Replacing all the caps made it good as new.

[Vertigo]

Hrm, this definitely isn't a monitor thing though, my TV works just fine.
I'll try fiddling with the strengths of the RGB signals and see what happens.