Door Interlock Switch; Indicator Lights; Buzzer; Wiring - Market Forge Industries MPS-3E Owner's Manual

Electric convection steamer

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6.0 TROUBLE-SHOOTING (Continued)

Door Interlock Switch

Malfunction of the cooker door interlock switch prevents timer indicator lights from turning on

and steam generator from operating when the timer dial is set. If steam does not enter the

compartment and the cooking indicator light fails to turn on with the door latch securely

engaged, the fault may be in the door interlock switch. Proceed as follows:

1. Turn off power to the cooker.

2. Disconnect wires to the door switch terminals.

3. Connect an ohmmeter between the terminals of the switch. The switch is marked "C" for

common, 'NC' for normally closed and "NO" for normally open.

4. Actuate the switch by closing the cooking compartment door. If a zero reading cannot

be obtained between the C and NO terminals, the switch is defective and must be

replaced.

5. Remove the ohmmeter and replace the leads on switch terminals.

If the cooker compartment functions correctly, with the single exception that the indicator light

fails to light during operation, the fault is a defective indicator light. A "burned out" or defective

light is verified by using an AC volt-meter at the leads, with input power on the selector switch in

the correct position for that timer, the timer set, and the door latches closed. If 240 volts is

present, the fault is in the indicator light and requires replacement. If 240 volts is not present,

the fault is in the wiring or control components (selector switch, timer or door switch).

If the buzzer does not sound at the termination of the operator-selected timer setting (timer dial

returned to "0 - Minute" position), the fault may be a defective buzzer. Buzzer operation is

verified using an AC volt-meter at buzzer coil connections with input power on and selector

switch and coinciding timer dial set at the "0 - Minute" position. If voltage is 240 volts, the fault

is in the buzzer, which must be replaced. If 240 volts is not present, the fault is in the wiring or

control components (timer or selector switch).

Using an ohmmeter, wiring continuity between the connections shown on the wiring diagram is

readily verified. This is best done in stages, removing only those wires required for each

continuity check. As each lead is replaced, it should be checked for evidence of corrosion, and

cleaned if necessary. All leads must be tightly attached so as to provide a good electrical

connection.

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