IGRINS Coldhead Power Cable Information

Prior to the 2014 September delivery of IGRINS to McDonald we had a scare with the coldhead.

It made growling/gurgling sounds. We contacted Brooks Tech Support (1800-367-4887) and chose the CTI option in the menu.

The coldhead is model number 1050 and the compressor is model 9600.

We were told to power off the system and inspect the pins for damage. Then, with a multimeter, while the coldhead was turned on, we checked the voltages between the pins on the coldhead end of the power cable.

The expected voltages are:

1-2: ~150V

1-3: ~220V

2-3: ~150V

Deviations of 5V are acceptable, but we measured deviations of 30V.

We then checked the compressor power output, the expected voltages are:

F-G: ~150V

F-H: ~220V

G-H: ~150V

These voltages read correctly, which clued us into a problem with the power cable. If the compressor power voltages were wrong then we would have to contact CTI again.

Doug Edmonston at UT found that one of the wires had broke off of the pin at the coldhead end of the power cable. He rebuilt the cable ends and the coldhead functions normally again.


Cable Specifics:

RTI part # - RT9702-3S.
Military Connector MS3137 (Deutsch DM9700 Compatible)
Link to RTI

Coldhead end Power connector:

Compressor end Power connector:

Pin Mapping (compressor > coldhead): H>1, G>2, F>3