Watlow EZ-ZONE
®
ST
•
16
•
Chapter 2 Install and Wire
Replacing the Solid-State Relay
on a Controller with a Contactor
(ST _ _ - (B or F) _ _ _ - _ _ _ _)
1. Pinch the release levers on the top and
bottom of the control module and lift the
right edge forward to detach the unit.
2. With a Phillips screwdriver, remove
the four nearest screws that were under
the module.
4. Lift the controller body, exposing
the solid-state relay.
5. Using a Phillips screwdriver, remove
the two screws connecting the solid-
state relay to the heat sink.
3. With a Phillips screwdriver, remove
the two screws at the top corners of the
controller.
Replacing the Solid-state Relay
1. Using a Phillips screwdriver, replace
the two screws connecting the solid-
state relay to the heat sink. Check that
the bottom of the solid-state relay is on
the left.
2. Place the controller body over the
solid-state relay and, using a Phillips
screwdriver, replace the six screw se-
curing it.
3. Snap the control module in place,
left edge first.
Note:
For controller models with a contactor (ST _ _-A _ _ _-_ _ _ _), the
solid-state relay must be mounted with the larger power terminals on
the right and the smaller control terminals on the left .
