Ok then shunting some of the current to ground is not the way to go.not, sure did not measure that yet
the smd leds are either 1W or 3W, wired in series, 15 pieces
I know it might be difficult, but if you can trace out the entire circuit we can figure out how to modify it. I had to do this several times in the past. Most notably with a Volvo fuel pump relay/controller board. Took a while to trace the whole thing out, but once I did that, I knew exactly what to do with it with no question about it. People have modified ATX power supplies too this way so they can use them as a sort of general-purpose adjustable power supply.