There is no provision in the 601XL plans for instrument lighting. I'm using LEDs on the bottom on the instrument panel lip, and incadescent lamps inside some of the instruments.
I bought a dual light dimmer to control the two sets of illumination. This is an initial test of the LED side.
1) Determined power supply polarity. 2) Temporarily wired supply to dimmer. 3) Temporarily connected one set of LEDs to dimmer. 4) Turned on power supply, and rotated dimmer control to test various levels of illumination. 5) Dimmer and port side LEDs check 5/5.