Just looked at the circuit diagram.

If the red led (D1) does not turn off, the reasons could be as under.

1) T3 is permanently on (May be faulty)
2) T4 is permanently on
3) VPE signal is at high logic level.
4) VPE comes out of pin 14 of parallel port. Check it with a multimeter if it ever turns off or not?


I had only one problem with this programmer. It does beahve strange with long cable (PC to PRogrammer connecting cable).

If you don't have any tool to check your parallel port, let me know. I will send you a utility to check parallel port.