Floating inputs when using LM1881 Sync Stripper

I'd like to use multiple LM1881 sync strippers to detect an active sync signal for use with a switching project. I have the three sync strippers connected to three different digital pins of a Uno. Each sync stripper will be connected to a composite video device using a y splitter, with the other end terminated to an Extron Crosspoint.

When I have the three composite video devices connected to the sync strippers, everything works fine: the sync stripper is returning a low signal which is read by the Arduino. And when I turn on any of the devices, the signal alternates low and high (as expected since sync is a data line).

However, I don't always want a device connected to every stripper. It would be nice if I could have any of the devices unplugged, and the digital pin read low. But when I do, the pin floats between low and high randomly.

I figured I needed a pull down resistor connected to each sync stripper output and ground to pull these pins low. I added a 10k resistor to ground, but the lines still float.

Am I missing something?

dubesinhower:
I figured I needed a pull down resistor connected to each sync stripper output and ground to pull these pins low. I added a 10k resistor to ground, but the lines still float.

I very much doubt that.

dubesinhower:
Am I missing something?

Yes, providing any information relevant to the devices and circuitry you are using.

Check the instructions!

If you are looking for the connected device to pull the input low,
why do you use a pull down resistor on the input? Do you
rather need a pull up there?