My openbox s9 is not switching between the horizontal and vertical polarities, scanning the vertical transponders twice, once calling them H and the next time calling them V. I have two lnbs connected, one ku (which works properly), and this c-band which will not switch. I can manually add the horizontal transponders, but they are dead, so once again it look like a switching problem. I checked the lnb with another receiver (pansat 3500), and it scanned all the transponders properly, so I think the lnb is good. So, two questions. Any ideas as to what the problem is, and what are the polarity switching voltages so that I can check and make sure that the proper voltage is getting to the lnb. Thanks.

You will have about 13 volts for Vertical, and 18 volts for Horizontal.
Voltage drop along the run is the most likely problem; not getting 18v to the LNBF.
How long is your coax? What switches are in line? What is the LNBF that won't switch?
Try your S9 out at the dish.

I thought I had read through the recent post, but I missed the one just below by jscud and his Primestar polarity problems. Although my situation is different, I do use a diplexer for my ota antenna and this c-band feed. I'll give that a look.

You will have about 13 volts for Vertical, and 18 volts for Horizontal.
Voltage drop along the run is the most likely problem; not getting 18v to the LNBF.
How long is your coax? What switches are in line? What is the LNBF that won't switch?
Try your S9 out at the dish.

Thanks, that is what I will do.

If you test the voltage at the lnb (end of your cable run) you should get 11-15 volts on V tps and 16-21 volts on H tps

what are the makes and model numbers of your lnbs?

Thanks all for the help. Just needed a push in the right direction. Turned out to be a bad port on my new diseqc switch. When I checked the voltage out of the switch, I saw the problem. Just switched the cable to another port and all is well in the c-band world. Is it necessary/desirable/possible to terminate the unused connections on a disecq switch? I only have three lnbs connected, and that always leaves a disconnected port.

It is not a good idea to use a terminator on a DiSEqC switch. Instead, use a cut-off F-connector to seal the fitting from weather damage and corrosion.