MKV IDOS Panel

Some years ago we added two PT100 RTD Inputs to monitor cooling water Inlet & Outlet temperatures on our three machines here which have been working perfectly. We are investigating why both of these inputs on one machine are recently reading approx. 10-12 Deg C higher than the actual temperature. This fault appeared a few weeks ago suddenly. We were not doing anything to the machine at the time and no unusual events were taking place. Troubleshooting so far is:

1) Read output from RTDs with calibrator. Output Ohms is correct for temperature being measured.
2) Simulate RTD with decade box at <C> TBCA, input displays 10-12 Deg. C higher.
3) Configure spare RTD Input and test, same results.
4) Replace <C> TCCA, same result.
5) Replace <C> TBCA, same result.
6) Check all wiring for grounds, noise, etc. Nothing.
7) Download IOCFG (various times). Nothing.
8) All <C> power supply voltages are within limits. No unusual diagnostics.

Is there anything in DIAGC that lets you look at RTD Inputs on TCCA? I only see mA Inputs and Outputs.

Any new troubleshooting tips, advice, etc. would be appreciated as this simple little problem is kind of driving me nuts.

 

After one more day of attacking this problem, I'll answer my own question in case someone has a similiar problem. In frustration I decided to virtually take the whole controller to pieces, clean, and put together again. In doing so we found that the JCC ribbon cable between TBCA and TCCA had some bad connections, a little contact cleaner and all is now well!!

 

Thanks for the feedback! The info helps everyone here, especially all the details of the troubleshooting!

markvguy