I fired up the power supply to test the "Power On" LED. I put a standard LED across the whole of the dual voltage output (-9.8/0/+9.8) so about 19.5 volts dc. This will allow it to discharge both pairs of capacitors in the PSU when switching off. This calculates to approx 750R for the anode resistor, but with the 20 mcd LED used I thought this was too bright and I don't like really bright lights on my gear. As can be seen in the centre of the picture I used a very small pot on the LED and turned it down till it was the brightness I wanted. I then measured the pot resistance (1k2) and soldered a resistor of that value on the long leg.