Fluorolog-3 v. 2.2 (11 Jul 2002)
System Maintenance
5-14
Warning:
Lethal high voltages are
applied to the photomultiplier cath-
ode. Turn off all instrument power
before installing or removing a pho-
tomultiplier. Never expose a pho-
tomultiplier tube to room light while
the high voltage is turned on.
Note:
Fingerprints on the glass
of the photomultiplier increase
the dark count of the tube.
Immediately remove finger-
prints from the photomultiplier
by rinsing with methanol and
wiping with lens tissue.
Emission signal detector
There is a wide range of photomultipliers available to optimize different wavelength re-
gions. When the R928P photomultiplier is replaced with a different detector, the emission
correction factors must be updated (see Chapter 11:
Producing Correction Factors
).
To install a new R928P photomultiplier,
1
Be sure that the instrument power is turned off.
2
Be sure that a liquid-N
2
-cooled PMT is warmed
to room temperature.
3
Remove the cables and wires attached to the
tube.
4
Carefully lift the tube from its base socket.
5
Remove the protective cap from the new
photomultiplier.
6
Plug the photomultiplier into the base socket.
Make sure the photomultiplier is positioned all the way down on the socket.
7
Carefully slide the photomultiplier into the base
socket.
8
Connect the cables.
This is outlined in the “Cable Connections” section in Chapter 13:
Re-assembly
Instructions
.
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