Thank you all for excellent documentations! The forum at its best!KH
Regarding PM750: it can be converted like MV692 ,its actually is a (kind of) MV692 without the pad and hi pass switches. The capsule in PM750 does indeed miss the internal resistor but the voltage drop is taken care of in the circuit (R2) as well as 10 dB pad (C1) and hi pass (C6). See attached schematic.