Pioneer SX-626 ReLEDding (2)
Because the lamps are fed with AC it had to be converted to DC with a diode bridge and a 2200uF capacitor. This yielded about 8.5 volts, enough to light two blue LEDs in series. A current limiting resistor of 470 ohms sets the required brightness. The blue filter of the scale removes a lot of light from the incandescent lamps so only relatively little light from the blue LEDs is needed.