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Thermo Fisher Scientific

It is not possible to turn retaining pawl (CLV) to unlock position


It is not possible to turn retaining pawl (CLV) to unlock position.



  • Apreo
  • Apreo 2
  • Scios 2
  • Prisma E
  • Quattro
  • Helios G4
  • Verios G4
  • Helios 5
  • Verios 5


  1. Be sure that microscope chamber is under vacuum. Press "P" button to pump the QL chamber and wait until "Ok" indicator turns on.
  2. Check that all cables are connected properly
  3. Check if 24V DC signal is present between pins 2 and 3 of cable connected to X1.Check resistance of solenoid coil between pins 2 and 3 on connector X1 QL body. Disconnect green plug and measure resistance between pins (see chapter 6 for figure "Connector for electromagnet and both microswitches"). If the electromagnet winding is OK you should measure about 150?. If not refer to 4022 190 54186 how to replace the solenoid.
  4. Remove cover from the left side and observe for mechanical locks of the retaining pawl mechanism (see chapter 6). The swivel barrier has to move smoothly.


  1. Vacuum inside QL not good
  2. Cable discontinuity
  3. Solenoid broken
  4. Internal mechanism is broken





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