MAGNETOM Symphony Cold Head (Cryocooler)
Two-stage cryocooler mounted in the magnet turret. Keeps the cold shields around 40K and limits helium boil-off. Runs continuously. When it fails, helium starts disappearing.
Fits
- MAGNETOM Symphony
- MAGNETOM Avanto (similar class)
- MAGNETOM Harmony (predecessor)
Diagnosis
- Boil-off rate above 0.05 L/hr on a system that was previously <0.03 L/hr
- Cold head temperatures climbing (monitor on service page)
- Audible change in compression cycle — louder, longer, or missed beats
Replacement
Warm compressor, have helium on-site, back up shim file. Not a field repair for the untrained — ISO or OEM.