Servicing
PMT High Voltage Power Supply Replacement
7-18
Model 42
i
Trace Level Instruction Manual
Thermo Fisher Scientific
4.
Remove the three retaining screws holding PMT base assembly to the
cooler using a 5/16-inch nut driver.
Equipment Damage
Do not point the photomultiplier tube at a light
source. This can permanently damage the tube.
▲
5.
Pull the PMT and PMT base from cooler assembly by twisting it
slightly back and forth.
6.
To install PMT, follow previous steps in reverse making sure to backfill
the cooler with dry air or nitrogen prior to replacing the PMT.
7.
Perform a photomultiplier tube calibration. See “
PMT Voltage
Adjustment
” in the “
Operation
” chapter.
Use the following procedure to replace the PMT high voltage power supply
(
Figure 7–9
).
Equipment Required:
PMT high voltage power supply
Nut driver, 1/4-inch
Philips screwdriver
Equipment Damage
Some internal components can be damaged by small
amounts of static electricity. A properly grounded 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 two PMT high voltage supply cables.
3.
Loosen the two retaining screws securing the assembly bracket to the
floor plate and slide the assembly towards the rear slightly and lift it off
the base screws.
4.
Loosen two screws on the input box assembly and lift the input box
assembly off the power supply.
PMT High Voltage
Power Supply
Replacement