> The first check after verifying voltages/wiring (which you said you did
in
 > another post) is cable length. You're begging for trouble if your cable
is
 > longer than 18 inches (0.5m).
 >
 > What's the length of your cable?

 I use a standard printer cable, which is about 1m in lenght. But I think
 this is not a problem. Isn't the 74HC244 chip solve the cable lenght issue?

 > The second thing is that you said you checked your voltages. Exactly what
> voltages did you get on each of the lines?

 When high, 3.3V at input of 74HC244. 5V at output.

 For the transistor's collector pin, it is 5V when turn on, 0.1V when off.
Another one is 13.1V when turn on, and 0.1V when off.

 One thing to mention is I make a mistake in the drawing that I posted
recently. I marked the MLCR/VPP pin with number 30. It should be 1 instead.
Anyway the wiring of my circiut was correct.

 WH Tan

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