Service manual

LUMISCAN ACR-2000 SERVICE MANUAL - SECTION 8.0 REPLACEMENT PARTS
8 - 3
PMT PRE-AMP PCA REMOVAL
The following tools will be necessary to remove the PMT system:
1. Flat blade screwdriver
2. Philips #2 screwdriver
The PMT PreAmp PCA is located at the top of the Collection Cylinder (Figure 8-2).
Remove the Main enclosure and Front cover to gain access to the PMT Preamp.
CAUTION: There are several wires coming from the tube's connector going to J6 on the PMT
PCA. These wires are fragile and could break if mishandled.
1. Unplug J14 on the DACQ.
2. Remove the PMT PreAmp assembly cover by removing the 2 pan head screws.
3. Remove the 3 cables going to the PMT Pre-amp.
4. Remove the 4 mounting screws from the PMT PreAmp PCA and remove the PCA.
5. Replace and secure PCA, reconnect cables and replace PCA cover.
PMT REMOVAL AND REPLACEMENT
When replacing a failed PMT it is required procedure to replace both tubes with a
matched pair. The gain characteristics of unmatched tubes can be such that they cannot
be balanced.
Newer models may have a different configuration than described below where there is a
single PMT tower containing both tubes. In this case there will be foam “doughnuts”
providing pressure and holding the tubes in place. In this case simply removing the top
cover and foam doughnuts from the PMT tower will allow you to remove the tubes.
Replacement is self-evident. Also note that in this newer configuration the blue filters
are not held to the tubes by photographic tape.
Ensure that power to the machine is off.
1. Remove the covers and the cable from the PMT sockets. Remove the PMT connection
cable from the tubes and the preamp.
2. Remove the four 9/64” screws securing each PMT Tower. Lift the towers off the
collection cylinder.