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2.3 LIMIT BOARD TEST PROCEDURE
Background
The limit board contains two optical switches each of which emits an infrared light
beam. When the light beam is interrupted, the voltage changes in a circuit that
tells the controller the position of the valve.
Procedure
To perform this procedure, disconnect, lock and tag the incoming power. Make
the volt meter connections leaving the limit board wired. Then reapply power to
take the readings.
Connect a DC voltmeter to the red wire and black wire.
You should measure approx. 5 VDC for the original Intellisys Controller with the
Starter Interface Board. If not, there is a problem with the controller or ribbon
cable.
On the SG Controller, a measurement of 2 VDC is good. Zero volts mean a bad
controller and 12 volts means a bad limit board.
Next connect a DC volt meter to white and black wire.
Power up the unit and manually move the inlet valve so the tang is in the closed
limit switch.
The Originally controller should measure 5 VDC.
The SG controller should measure 10-12 volts DC.
If not, the limit board is bad.
Next, connect a DC voltmeter to green and black wire.
Power up the unit and manually move the inlet valve so the tang is in the open
limit switch.
The Original controller should measure 5 VDC.
The SG controller should measure 10-12 volts DC.
If not, the limit board is bad.
See FSM Section B, Sheet 27, in the blue Field Service Manual for more
information pertaining to the limit board on the SG Controller.
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