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Cryogenics: Troubleshooting

Diodes incorrectly ordered​

Summary​

During commissioning, an issue was noted where diode ordering appears to slip during operation.

Diagnosis​

  • The raw voltage of channels known to be working will read approximately 2.5 V
  • Presuming the initial cooldown has been completed, the thermometers on the 50 K stage consistently read below 30 K and some other diodes read much hotter than expected.

Treatment​

  1. Stop the current cycling and select "Warm to 4 K"
  2. Restart the MC-CAL program and restart cycling. If requested, confirm the heat switch is open

Other notes​

The cause is believed to be related to changes in grounding causing the I2C addressing to slip. This is not envisaged as likely during deployment. Software automatically makes sure the addressing is correct at startup.