I'm in the process of setting thrust position probes on an older frame gas turbine. We typically set probes "zero active" where the axial position will read 0 when riding on the active thrust pads.
I'm more familiar with the Bently 3500 system where you can use the computer to adjust Normal Thrust Direction and Zero Position voltage settings.
However, on the 3300 (specifically the 3300/20 card), there are jumpers on the circuit board that you can set for Normal Thrust Direction, which I've configured. But, the zero position adjustment seems to involve some gain adjustments to "ZA" and "ZB". I cannot find these gain adjustment knobs.
Any assistance would be appreciated.