Signal expected on parallel port

[Kebmo]

Hi, I've got a little question: I picked up a 5V-peak-ppm-signal from the printed circuit board of my transmitter and assembled the 680kOhm+4.7V-diode interface for the parallel port. The voltage drops to 3V at pin 10 of the sub-d-connector. Sometimes, FMS works good with the signal, but normally the Program toggles betwenn "Signal vorhanden" and "kein Signal". )o:
I thought that the level was too low, so i built up a new circuit and now i've got 5V-peak on pin 10.... but there's no signal anymore.
Can anybody tell me the correct voltage level? Perhaps 3V is ok, but what about the input resistor of the parallel port? There might be a problem if it's very small. Then my signal breaks down. I tested it with a couple of resistors and i lost the 3V level. Perhaps the problem is the "interrupt-problem" with FMS (i I don't have to built up a new circuit (o: )? Does anybody know?

thx

Keb

[wahlstrom]

test to check the BIOS: abort during start up with F1 och F2 or what is correkt for your PC. In BIOS go to parallelport-settings and set it for STANDARD MODE or SPP-MODE or AT-MODE or EPP-MODE (not bi-direktional-mode or ECP-mode). Then I´ll think you get a steady signal.