Hi All,

Inherited a DT85 Series 3 that came hooked up to the rig I'm using (high temperature reactor). It has 4 n-type thermocouples plugged into it and I've run a number of tests so far without any issues.

I have no experience using this hardware so I haven't touched any of it.

Near the end of my last test I just lost signal all of a sudden.
Reading the screen said that I had a 'RefError' on all the thermocouples.
I tried a soft reset, nothing.
After a hard reset I got a 'Self Check Fail' error.

What's happened? I'm completely in the dark here, no idea what to do to try and trouble shoot!

Any help welcome!

Hi mshaw,

Thermocouple reading requires temperature compensation at the connection point (dataTaker terminal) because that point is another junction of 2 metal. To read temperature at the junction we have a RTD sensor attached to copper path of our PCB.

When "RefError" appear, the logger failed to access RTD sensor, possibly because some fault. The fault may happen due to ground loop. I recommend you to contact the nearest distributor for service arrangement.

However if you want to keep using the logger until the project finished because you have no replacement unit, you can try to create temperature reference using an external RTD/ thermistor which put close to the logger terminal. It will not give the same accuracy as internal RTD, so I am not sure if you can use this method.

Please check isothermal block information within thermocouple section of DT8x manual (part O - Sensors and Channels) for more information.

Best regards,
Rudy Gunawan

Thanks Rudy!

It seems a temporary fix is to run a couple of self check until it decides it's happy again, then it keeps working. But that doesn't stop it tripping every now and then.
I'll see if I can get someone to look at the internal RTD.

Thanks for the info!

Regards,
Matt