80 Model 5380 PFPD Operator’s Manual
Rev. 3.1
Replacing the Optical Filter(s)
If the operational mode of the PFPD is to be changed, the optical filter may have to
be replaced in the PMT housing assembly (see Figure 6.3). Appendix A provides a
list of suitable filters for different modes. If the optical filter(s) needs to be re-
placed, the following procedure should be used.
1. Using WinPulse, set the PMT voltage to zero. Disconnect the PMT HV and
the PMT signal cables from the back of the Detector Controller
2. Turn off the Detector Controller and allow the PFPD to cool to room
temperature.
3. Detach the PMT housing assembly (Part #286096) from the PMT mounting
by loosening the PMT thumbscrew (Part #177065) and gently pull off the
housing. Wiggle the housing back and forth if necessary to remove it. Open
the PMT housing assembly by unscrewing the PMT housing from the cap (see
Figure 6.3).
4. Place the PMT housing assembly onto a clean, lint-free lab tissue, ensuring
that none of the contents fall out.
5. Remove the existing filter(s) and Viton O-ring from the PMT housing and
place them onto a clean lab tissue or other optical storage container.
6. Install the Viton O-ring and the replacement filter(s) in the PMT housing.
7. Verify that the PMT is not broken and is properly mounted in its socket.
Carefully screw the PMT housing cap back onto the body of the PMT hous-
ing. Lightly tighten the PMT cap until the filter(s) does not rattle or move
easily. If the filter(s) is loose when the cap is fully tightened, remove the PMT
again, install an additional Viton O-ring to take up the excess space, and
reassemble the PMT housing.
8. Verify that the PMT Viton O-ring, which causes the PMT housing assembly
to fit snugly onto the PMT mounting, is in place and not damaged. Replace if
necessary. Twist the PMT housing back onto the PMT mounting, and reattach
it using the thumbscrew.
9. Route the PMT cables to avoid high temperature zones, sharp edges, or places
where the cable could be pinched or sheared.
10. Connect the PMT signal cable and the PMT HV cable to their respective
connectors at the back of the Detector Controller.
11. Using WinPulse, reset the PMT voltage to its appropriate voltage (e.g.,
nominally 600 V).
12. Optimize the PMT voltage. See step 12 in “Starting the PFPD System” in
Chapter 5.
!
CAUTION:
Do not use
excessive force
when tightening
the PMT housing
together. PMTs
can be easily
damaged by
overtightening
the housing
assembly.
!
CAUTION:
Touching the face
of the PMT tube
can damage the
optical sensitivity
of the PFPD.
!
WARNING:
Handling the
PFPD while it is
hot can cause
serious burns.
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