HP 5890 SERIES II Service Manual page 129

6. Remove the spring securing the PMT assembly to its support bracket.
7. Cut the cable- tie securing the resistor network cable assembly to the PMT assembly tube
body.
8. Holding the tube body, unscrew the end cap (counter- clockwise) until the threads disengage.
9. Grasp the resistor network cable assembly and pull it (along with the end cap and PMT) out of
the tube body.
(CHIMNEY AND BRACKETRY
REMOVED FOR CLARITY)
10. If the PMT is not to be replaced, clean the window of the tube with a lint- free lens tissue and
proceed to step 15 . (If necessary clean the window with a solution of soft soap and warm wa-
ter. Rinse with distilled water.)
Replace the PMT if there is any evidence of chips, scratches or cracks in its window
surface area. A damaged tube must be replaced before continuing to operate the
instrument.
11. If the PMT is to be replaced, carefully remove the PMT from the socket associated with the re-
sistor network cable assembly, in the end cap.
12. Dispose of the old tube in a safe manner.
13. Carefully remove the new PMT from its packing case and insert the base of the tube into the
socket of the resistor network cable assembly ). Be very careful when inserting the tube in order
to prevent damage to its contacts (observe keying).
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TUBE BODY
PHOTO-
MULTIPLIER
TUBE (PMT)
SVC 4- 59
PMT ASSEMBLY
O- RING
END CAP
RESISTOR NETWORK
CABLE ASSEMBLY