1.4Troubleshooting
Problems with this equipment maybe grouped into five broad categories:
1.Failure or malfunction of a Power-Supply System component.
2.Failure or malfunction of the Controller.
3.Failure or malfunction of an Autofill/Autoskim System component.
4.Failure or malfunction of a Water Heating System component.
5.Failure or malfunction of a Basket Lift System component.
Sections 1.4.1 through 1.4.5 briefly explain the functioning of each of the systems mentioned above. Section 1.4.6 contains troubleshooting guides that provide systematic procedures to isolate and identify the specific source of a problem. A wiring diagram is located at the end of the chapter.
1.4.1 How the Power-Supply System Works
Line voltage is supplied to the system via a power cord that is plugged or hard-wired into the store’s electrical service. The power cord is connected to pins 1 and 5 of an 8-pin terminal block. Line vol- tage is supplied to a 24VAC transformer from pins 2 and 8 of the terminal block. Pin 7 supplies 24VAC to a heat relay, which controls line voltage to the blower motor and 24VAC to the gas valve via the ignition module. The transformer supplies 24VAC to the controller, to the coils of the 24VAC relay, and to the solenoid valve on units equipped with the Autofill option. On units equipped with basket lifts, line voltage is supplied to a 24VDC basket lift relay from pin 6 of the power cord terminal block. Line voltage to the basket lift motors is supplied via the basket lift relay.
1.4.2 How the Controller Works
The SMS III controller provides the interface between the operator and the system components. The controller is powered by 24VAC supplied through pins 1 and 2 of the wiring harness. Internal cir- cuitry senses the water level and water temperature. Depending upon the conditions sensed, the con- troller energizes or de-energizes the solenoid valve which controls the water level. The 24VAC re- lay controls burner firing which controls water temperature. The controller also controls the lower- ing and raising of the basket lift, and activates an audible alarm to signal the operator that a cooking cycle has completed. A rectifier in the controller converts 24VAC to the 24VDC required by the basket lift relay. The controller signals for heat via pin 4, grounds the solenoid valve via pin 6, and senses water level via pins 7 (low) and 9 (full). The temperature probe connects to pins 13 and 14. The basket lift relay connects to pins 10 and 12. The sound device connects to pin 11.
1.4.3 How the Autofill/Autoskim System Works
The heart of the automatic filling (Autofill) system is a normally closed solenoid valve that opens when 24VAC is applied.
The ground for the solenoid is supplied (via pin 6 of the controller wiring harness) so long as the shorter of the two water-level sensors is not in contact with the water in the cookpot. When the water in the cookpot reaches the shorter of the two water-level sensors, the sensor is grounded. This causes the controller to break the solenoid ground, closing the valve. Starch or lime build-up on the sensor may keep it from grounding, therefore always make sure the sensor is clean and its lead (pin 9 of the controller wiring harness) is firmly connected. Also, in order for the sensor to ground, there must be some mineral content in the water (pure water is non-conductive). Consequently, the unit will not operate correctly with distilled, highly filtered, or deionized water. If water of these types is
