7 - 2 1.
PHOTOMULTIPLIER BRACKET ASSEMBLY 2A1A1A7 AND PHOTOMULTIPLIER TUBE
INPUT CODE: PMTLED
This module tests photomultiplier bracket assembly 2A1A1A1A7 photomultiplier
tube (PMT) temperature, and ability to detect light energy.
If an error is detected during any of the following checks, a prompt is
displayed at the completion of the tests.
The PMT cooler is checked by reading the OSA temperature sensors for 5.0 to
The OSA PMT is turned on and after a 15-second delay, the PMT high voltage
test point is checked for -3.0 to -5.5 vdc.
The operator is then prompted to
connect the I-250 illuminator to the adapter on the OSA assembly door 2A1A1 and
adjust the illuminator for a voltage of 7.80 to 8.20 volts. The PMT level is then
checked for each of 6 loads.
PMT test 3 is selected and PMT output checked for 7.80
to 8.20 vdc.
PMT test 3 with filter is selected and PMT output is checked for 0.72
to 0.88 vdc.
PMT test 4 with filter is selected and PMT output is checked for 7.00
to 9.00 vdc.
PMT test 2 is selected and PMT output is checked for 0.72 to 0.88 vdc.
PMT test 1 is selected and PMT output is checked for 0.04 to 0.12 vdc. PMT test 5
is selected and PMT output checked for 0.04 to 0.12 vdc. PMT test 6 is selected and
PMT output is checked for 0.72 to 0.88 vdc.
PMT test 6 with low impedance is
selected and PMT output is checked for -0.04 to 0.04 vdc.
b. REPLACEMENT PROCEDURE REFERENCE
The following list provides a cross reference of replacement items to
The item column identifies the item to be replaced by
reference designation and part number.
The reference column identifies the
procedural paragraph used to perform the replacement action. The VDT screen will
display the proper sequence of repair/replace actions.
(Ref Des/Part No.)
2A2A6XX (SLOT 408)/69331B
2A2A6XX (SLOT 409)/69331B
2A2A13XX (SLOT J4)/AC4720