While Keita will report the detail about the heater wiring trouble shooting, here is the quick report for the JAC heater functionality.
The attatched plot shows the two thermistor signals (top/bottom) and the heater input (middle). The temperature is reasonably changing with the heater driver input.
JAC in-vac tri-cable was swapped. (Masayuki, Jennie, Jason, Keita)
The cable that failed (D2500336-V2, S2501241) was pulled out of the chamber. (In the process, one of the body mode damper crossbar had to be temporarily removed to release the cable. ) The cable was wrapped and put in a bag without further testing (yet).
Jennie and I tested the new tri-cable (D2500336-V2, S2501242) in the optics lab and it was good (i.e. every pin was connected to the pin it is supposed to be connected, no cross-wiring, no short circuits).
The new cable was installed in chamber.
I checked the in-chamber connection from the in-air side of the D4F10 feedthrough. Pin13 wasn't connected to anything, ditto for the chamber ground, thermistors showed about 11kOhm each, heaters were about 50 Ohm each, PD anode and cathode were good, no cross-wiring and no unintended short circuits.
After connecting the in-air cable to the feedthrough, PZT and Trans PD worked right away.
After connecting the heater cable to the driver chassis, we confirmed (using the breakout board and a DVM) that the voltage across the heater elements was ~1.4V when H1:JAC-HEATER_DRV_VSET~3.6[V?], H1:JAC-HEATER_DRV_VMON~1.6[V?] and H1:JAC-HEATER_DRV_IMON~-0.098[A?]. Maybe 1.4V is close enough to 1.6V (0.2V might be the voltage drop of the in-air cable?) but I don't understand the logic about VSET being 3.6V nor why IMON is negative (in my mind it seems logical if IMON~1.6V/25Ohm = 0.064A).
But it's good to know that it's doing something.