I am not sure I understand everything you said. I would not connect an open collector directly to Vcc without knowing more about the circuit. For example, if the emitter is connected to ground, as in a comparator, then when the output turns on, you effectively would have a short to ground if the collector were tied to Vcc. The datasheet for IC devices will tell you whether you can leave the collectors floating or not.If so, you can connect the output directly to Vcc, not through a pullup resistor. BTW, because the output is "open", not connected to other circuit, there's no current flowing to the output in open state, thus no voltage drop on the pullup resistor, in effect the voltage at output is almost the same as Vcc
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