Using Raspberry Pi to read open collector outputs from tally connector
Send 3.3V from a Rasberry pi GPIO to Pin 7.


No. Pin 7 should simply be left unconnected. The outputs are enabled when pin 7 is left open.

Other than that, a simple 1k to 10k resistor as a pull up to 3.3V on each output is all you need. You have the general idea., except as another answer mentioned, these are active low outputs. Open collectors are pulled up to VCC and actively pulled low to turn on. So your RPi code requires you to look for a high to low change, a 0 For on instead of 1. This is inverted logic. 

This is the typical connection scheme. The 3.3V is connected to the resistors, which pull the lines up (hence, pull-ups). 






simulate this circuit &ndash; Schematic created using CircuitLab