Apple II/+ power indicator light fix

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Joined: Feb 2 2009
Posts: 61

Awhile back I posted a question on where I could find a replacement bulb for the Apple II+ Indicator light.

Mike W had suggested usin a "Grain of Rice" or a "Grain of Wheat" type incadecent bulb.

Instead I used a white LED with a max current rating of 25mA. A Radio Shack item and a 100 Ohm resistor. This configuration only draws 16mA or roughly 1/6 the power of the original bulb.

The LED voltage drop was measured at 3.4 volts, so a 100 ohm resistor in series with this LED across the 5 volt power supplied, would limit the current rating to 16mA.

By using a very small dremel bit the diameter of the LED wire itself, I drilled out two small holes at 90 degrees from the original mounting holes on the keyboard PCB. I slipped in the LED, soldered one end of the LED to one of the electrical mounting hole and attached the other LED wire through a 100 Ohm 1/8 Watt resistor to the other electrical mounting hole. Even with the 16mA of current, I found this to be too bright. I could use the 110 Ohm or 150 Ohm resistor of the same power rating. The color was the same as the original bulb. And I get 600,000 hours of life on this LED.

-RocketScientists