N64 RGB brightness dims after 5 seconds

I have run into a problem with my rgb modded n64. For the first 5 seconds of any game the brightness is at a perfect level, then it dims to a darker level that is hard to see. Has anyone else had this problem with there system? Added an amp but did not change the brightness, does the same starting bright then going dim after 5 seconds. Every game I have does this, and on multiple tv's tested with same results. No other console I have modded does this either. Also I have the sync running though pin 7 of the AV out like I have read on here to do. I had it with c sync before and had same results with it auto dimming.

 

did you install the RGB amp when you did the install?

 

caps in the cable?

 

No the amp came after initial rgb wiring. I did the basic 3 wires from the chip to the AV out, brightness was very dark. So I read about adding THS7314DR amp, it helped with brightness but I lost color. Tried 4 different amps with no improvement. Then I read using pin 7 for sync increases brightness, it did and that's when I noticed the auto dimming. Tested the first basic 3 wiring on my brothers vizio because it doesn't appear very dark, but it still auto dims with either sync output connected.

And yes there's 3 220uf connected to rgb lines, everything else straight to scart pinout

 

remove the caps

 

Ok I'll try that when I get home, thanks. I thought it was a standard to have the caps on the rgb lines, every other of my scart cables do.

 

Thank you so much Bad_Ad84, that worked and the picture is perfect, no amp needed, saved me a lot of trouble and now I can finally put my n64 back together.