25 March 2022 (Friday) at 21:00, went to QIL to start warmup.
- Cryocooler was turned off at 21:21
- Heater output was disabled - it seemed there was an issue, and therefore I opted for passive warmup only.
Heater Issue Troubleshooting
Symptom: Heater Output was enabled but reporting only .35 W and "Err" indicator.
Symptom: When output was disabled, a fan noise was terminated. When output was reenabled, the same fan kicked back on. The fan was driving much harder than I had ever heard it before.
Symptom: The output indicated .35 W but the test mass temperature was 66 K. Past heater power for steady state at 120 K was on the order of 1 W.
Per CTC 100 manual:
- pg 9 (100W heater outputs) indicates: "If the temperature of either PCB exceeds 60°C, the CTC100 automatically shuts off the corresponding output" which was not the case.
--> Apparently not an overtemperature situation.
- pg 9 (Hardware faults) indicates a list of error conditions which are accompanied by pop up windows.
--> This error had no pop up window, not quite sure what to make of that except that the controller doesn't think our issue is something it can identify.
- pg 29 (The system fan) notes that "The main system processor reads the desired fan speed from each I/O card and sets the fan to the fastest requested speed".
--> Suggests that the louder fan noise may have indicated higher temperature condition, even if not an over tempearature condition.
- pg 41 (Numeric) describes that in the typical numerical view of the data channels, the message "Err" that I saw on the heater channel indicates "an internal error has occurred".
--> No explanation of what an "internal error" is, but in this case I suspect it could reflect that the heater output is not coupled the input Workpiece temperature.
Best Guess: the symptoms and the lack of any apparent controller-identified fault suggests that the heater may have debonded. I didn't look at temperature history, so I'm not sure if there was a point where the heater was bonded to the test mass during this run.
Next Steps: We should open up and investigate.