Bad temperature readings with built in CJC on TC2095 and SCXI 1303

[GarbageCan]

Hi, I'm testing some of the older DAQ systems lying around my lab and I've been having some trouble getting a good thermocouple reading in LabVIEW.

I have a NI PXI-1052 chassis with a PXI-8196 controller, that my signal conditioning modules are hooked into. I have a couple of SCXI 1102Bs, and an 1100 module installed. And so I wanted to do some test thermocouple measurements with a couple of terminal blocks, the SCXI 1303 and TC2095 but had problems when I had in LabVIEW the CJC source set to 'built in'. I hooked some of K-type thermocouples to both of these and just wanted to see them measure the temperature of the room and this is what I got:

SCXI 1303

If I have the CJC source set to built in, I get a temperature of about 36.7 degC (The room is no more than 25).

If I set it to a constant of 23 then I still get a high value of 29.5 degC

TC2095

I I have the CJC source set to built in, I get a temperature of 480 degC (I don't feel like that is accurate)

If I set it to a constant CJC value of 23 then I get 23.5 degC which is inline with the thermometer in the room

With the constant CJC value tests, it repsonded to me touching the thermocouple tip by raising >5 degC normally. In the built in tests, touching the tip didn't affect it.

Just to doublecheck that it wasn't a problem with my LabVIEW VI, I used the thermocouple example VIs and had the same result with a prettier front panel.

I've tried moving the terminal blocks on to different modules, and also since the bad readings only seems to be when the built in CJC is selected, I figure the problem is with the terminal block and specifically the cold junction thermistor on both. Does that make sense or am I off in assuming that?

I've also done a voltage measurement of the _cjTemp channels and for the 1303 I got 1.14831V and the TC2095 gave me 0.0005 (The SCXI-1303 temperature sensor outputs 1.91 to 0.58 V from 0 to 55 °C). 1.14V comes out to 31 degC for me which would be why I'm getting such a high value with the built in for the 1303, and then I don't understand the 2095 reading. Is it a thermistor as well?

Sorry this was kind of a scatter shot post, I'm just trying to give as much information. But ultimately are the cold junction sensors the problem, and what steps can I take (if any) to fix them.