Twilight Zone Clock
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The Twilight Zone clock is a relatively troublesome toy on the emachine.
The electronics suffer from two design problems:
- Excessive heat generated inside the clock
- Special optos needed to guarantee reliable operation
In addition, the clock optos can fail in the event of switch matrix shorts. And the connectors between the boards can become unreliable.
The first problem with the clock is that it overheats. About half the comes from the incandescent bulbs, which generate 4.8W. The balance comes from the opto emitter circuits, which generate a total of about 4W of heat (8 * 40mA* 12V). The clock therefore becomes hot, and the opto emitter reistors get hot enough to burn the board. Plus, the clock case yellows more quickly.
Aftermarket clock boards address the heat issue due the the lamps, but the opto issue remains. There are some designs that address all issues, but these are not commonly available.
Replacing the Optos