How To Select the Trip Point Action Chapter Four: Operation
38
6. Use a small screwdriver to adjust the trip point adjustment pot labeled “TP A”.
Refer to Figure 6, page 21, for the location of the trip point adjustment pots. Turning the
pot clockwise raises the trip point setting.
7. Repeat steps 1 and 2 to adjust TP B.
8. Slide the enclosure over the unit and press it in place.
9. Attach the hex nuts to the I/O connector and Philip screws removed in step 3.
10. Reconnect the leads and wires.
Refer to How To Select the Trip Point Action, page 38, to change the action of the trip points.
How To Select the Trip Point Action
Equipment required: 4.8 mm hex or open-ended wrench
The 649 controller is initially configured with TP A set to trip high (it is on when the pressure is
above the trip point pressure) and TP B set to trip low (it is on when the pressure is below the trip
point pressure). To change the action of the trip points you must remove the cover of the unit and
change jumpers on the Transducer board. Each trip point has a jumper block with the jumper
positions labeled TL (trip low) and TH (trip high).
1. Stop the gas flow through the 649 controller.
2. Remove any leads or wires attached to the connector on the 649 controller.
Use a 4.8 mm hex wrench (or open-ended wrench) to remove the hex nuts on each side of
the I/O connector.
Refer to Figure 6, page 21, for the location of the hex nuts on the I/O connector. Use a
Philips screwdriver to remove pairs of screws from both ends of the enclosure.
Place the hex nuts and screws aside for safe keeping.
3. Position the controller with the front side facing you, and pull up on the enclosure to
remove it.
The board assembly will be visible, with the Transducer board facing you and the Control
board behind it.
4. Locate the jumper blocks labeled “JP4” and “JP3” in the middle of the Transducer board.
Refer to Figure 14 for the location of the jumper blocks.
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