Hi!
There's a clue in the MBT Service Manual!
https://www.paceworldwide.com/sites/default/files/MBT%20250%20Service%20Manual_0.pdfPins J1-4 is annotated "CH1 RTD" and Pin J1-5 annotated "RTD Return" - the fact that it's known that one of the calibration Modules is a 100.0R resistor indicates the lower cal. set point for the microprocessor is "0.0C", and also identifies the "C-1" and "C-2" calibration resistors as connecting between "RTD" and "RTD RTN" per channel, so with this info to hand, plough thro' the service manual, and make a note of the max. temperature the unit is designed to work to, which is 482.0C., so by reference to an RTD PT100 Comparison chart:-
http://electrolyseur.fr/ZIP/Pt100.pdf. . .we read "482C" as about 274.8R, which you can make up with 1 x 240R, 1 x 33R and 1 x 1R8, all in series - you should be able to get these in 1% E24 series!
The C-1 and C-2 calibration plugs are simple 6-pin DIN connectors - RS, Mouser or Digi-key should have something that matches the plugs on one of your Pace Handpieces you can use to make them from!
Obviously if there's anyone got a pukka C-2 then this is what you need, but it you get really stuck and the value I suggest for calibration at 482C doesn't work or the Pace micro doesn't accept it (recognised by an error indication or the unit "hanging" at the "C-2" stage, then try again, but this time, try using a "C-2" value of 400.0C or 500.0C from the PT100 chart in turn until the micro accepts the figure and completes the cal!
Hope this helps until someone can read off a pukka OEM "C-2" plug for us!
Chris Williams