Thermo Scientific 42i Instruction Manual page 197

Photomultiplier Tube
Replacement
Thermo Fisher Scientific
5. Disconnect plumbing connections from the reaction chamber.
6. Disconnect the cables from the PMT high voltage power supply, the
input board, and the measurement interface board. Remove all tie-
wraps securing the cables.
7. Loosen four captive screws holding cooler to floor plate and remove the
cooler assembly with the reaction chamber.
Note If only the cooler is being replaced, remove the PMT and reaction
chamber from the old cooler and install them on the new cooler.
8. Install new cooler by following previous steps in reverse.
Note Fasten knurled fittings on reaction chamber finger tight.
Make sure that the heat shrink covered tubing between the reaction
chamber and the converter is light tight at the connections.
9. Re-install the measurement bench. Refer to
Measurement Bench and Lowering the Partition
Use the following procedure to replace the PMT tube.
Equipment Required:
Photomultiplier tube and PMT base
Nut driver, 5/16-inch
Flat blade screwdriver
Philips screwdriver, small
Equipment Damage Some internal components can be damaged by small
amounts of static electricity. A properly ground antistatic wrist strap must
be worn while handling any internal component.
1. Turn instrument OFF, unplug the power cord, and remove the cover.
2. Disconnect the high voltage cable from the PMT power supply and
unplug the BNC cable from the Input Board.
Servicing
Photomultiplier Tube Replacement
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"Removing the
Panel" in this chapter.
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Model 42i Instruction Manual 7-13