Valve Box Assembly Removal - HP 5890 SERIES II Service Manual

Valve Box Assembly Removal

1. Place the main power switch in the off position.
HAZARDOUS VOLTAGES ARE PRESENT IN THE INSTRUMENT WHEN THE POWER
CORD IS CONNECTED. AVOID A POTENTIALLY DANGEROUS SHOCK HAZARD BY
DISCONNECTING THE POWER CORD BEFORE WORKING ON THE INSTRUMENT.
2. Unplug the line power cord from its receptacle.
3. Allow some time for the oven and heated zones to cool.
4. When the oven has cooled, turn off all gas supplies.
5. Switch the solenoid valve off so the actuator is in its fully extended position (Figure 2- 29).
Place the main power switch in its " OFF"position. Disconnect the line power cord from its re-
ceptacle.
6. Remove the back panel and allow sufficient time for the oven and heated zones to cool; then
turn off supply gases and the air supply to the solenoids at their sources.
7. If variable restrictors are present, remove their mounting hardware in the following order: two
M4 screws, hex nut, and mounting bracket for each restrictor valve.
8. Remove two, valve box top assembly, mounting screws, one located near the left front corner
and one along the right side edge near the middle. Lift the valve box top assembly straight off
the valve box. Be careful not to move the valve rotor index pin from its " at rest"position.
If valve/actuator alignment is to be made, see " Valve/Actuator Alignment"in this
section, but do not perform steps 9 through 11.
9. To reassemble: Align the two mounting holes in the valve box top assembly with the standoffs in
the valve box. Lower the box top assembly until it rests on the standoffs.
10. Secure the valve box top assembly with two M4 mounting screws. Tighten these screws firmly.
Reinstall hardware for variable restrictors if present.
11. Exercise the valve(s) on and off a few times to verify operation.
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NOTE
SVC 7- 15