HP 5890 SERIES II Service Manual page 113

The following steps require protection against ESD (Electro- Static Discharge).
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Use a grounded wrist strap (part no. 9300- 0969 - large, or 9300- 0970 - small)
connected to a suitable ground. Failure to heed this caution may result in
damage to the instrument.
When storing or in between handling of PCBs (Printed Circuit Boards), always
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place them in static control envelopes or enclosures.
20. Disconnect the NPD bead power cable from the detector PCB by pulling it straight off.
21. Remove the NPD detector PCB by sliding it out of the main PCB (at the right side of the instru-
ment). Removal of the PCB will withdraw the interconnect from the thermal strap. Use caution
to avoid damaging the spring at the end of the interconnect.
22. Use a spanner wrench (part no. 19301- 00150) to remove the base spanner nut from the detec-
tor weldment.
23. Remove the thermal strap by removing the five screws securing it to the instrument.
24. Remove the two screws securing the detector
weldment to the instrument.
25. Slide the insulation plate out from over the de-
tector weldment.
26. If the detector is to be reused, cap the detector
weldment at its upper opening, using a detec-
tor cap, and at its lower opening, inside the col-
umn oven.
27. Remove the insulation around the detector
weldment to expose the two screws securing
the weldment to the instrument.
28. Lift the base up enough to expose the heated
block, heater and sensor cartridge wires.
29. Carefully slide the two cartridges out of the
block. (The smaller of the two cartridges is the
sensor and must be handled gently in order to
prevent breakage.)
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INSULATION
PLATE
HEATED
BLOCK
SVC 4- 43
JET
BASE SPANNER NUT
THERMAL STRAP
HEATER
SENSOR