Voltage on a disconnected part of the circuit?
Electronic peek-a-boo!







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. Open circuit switch loaded by voltmeter impedance.

I think you are expecting about 1.5 V across TA and TB. If you redraw your circuit as open switches (transistor bases pulled to ground) it should become more obvious what's happening. The internal resistance of your meter is much lower than the "infinite" resistance of the other transistor switch. The voltmeter short-circuits TA leaving all the voltage across TB. As soon as you move the meter across TB it disappears there and appears across TA. It's electronic peek-a-boo!

If you look up your meter's impedance - probably 1M or 10M - and put that value resistor across the other transistor you should get half the voltage reading on your meter.