Finish Thompson BE-55C - Manual (Page 17)

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Possible Cause 3: Low Level control system not satisfied.
Insufficient liquid level in Process Tank. Verify that the Process tank has been filled (minimum
8-gallons).
Check the red LED on the Low Level Control Board (located in the upper left corner of the BE’s circuit
box, this will be the second board). When liquid touches the Level Probe, it grounds the probe and
lights the LED on the Level Control Board.
 If the LED is lit, proceed to Possible Cause 4.
 If the LED is not lit, and technician is certain that liquid is in the Process Tank, the unit is not
sensing the liquid.
Check the Level Probes wiring. Touch the probe’s wire (#23) to the probe’s pipe. If the LED lights,
remove the probe and check for a clog in the pipe that would prevent liquid from reaching the probe.
Also check continuity between the probe’s wire terminal and the probe’s rod. If there is no continuity,
the Level Probe is defective and must be replaced.
If the LED still does not light, check the Process Tank’s ground wire connection. This wire is attached to
the Process Tank with a screw (behind the heaters cover). This connection can become corroded and
not allow the Level Control to function. Remove the screw, file the metal clean, and re-attach the wire
with a new screw and new crimp connector. If the screw is too corroded to remove, drill and tap a new
hole for the ground into the same metal slab, next to the old screw.
CAUTION: Do not drill a hole into or through the Process Tank.
Drill into the welded metal slab only.
Maximum drill depth is 1/4”.
If everything above checks out O.K, then check for voltage (240V) across wires #26 and L2 to the
on/off switch, if no voltage is present, then the Level Control Board is defective and must be replaced.
Possible Cause 4: On/Off Switch is Defective
WARNING: Electrical shock hazard present. A qualified electrician should perform
electrical servicing.
 With power on to the unit, first check if 240 volts are present at the switch (across wires #26 and
#L2). If voltage is present, depress the On/Off switch to the on position and check for 240 volts
across wires #13 and #18A.
 If no voltage is present at wire #13 and #18A with the switch in the on position and there is voltage
at wires #26 and #L2, then the switch is defective and must be replaced.