Viking DMOC205SS, VMOC205SS service manual Description and Function of Components

DOOR SENSING AND PRIMARY INTERLOCK SWITCHES

The door sensing switch in the secondary interlock system is mounted in the upper position on the latch hook, the primary interlock switch is mounted in the lower position on the latch hook. They are activated by the latch heads on the door. When the door is opened, the switches interrupt the circuit to all components. A cook cycle cannot take place until the door is firmly closed thereby activating both interlock switches. The secondary interlock system consists of the door sensing switch and secondary interlock relay located on the control circuit board.

LATCH HOOK

THIRD DOOR SWITCH

DOOR SENSING

SWITCH

MONITOR SWITCH

LATCH

HEADSPRIMARY

INTERLOCK SWITCH

SWITCH LEVER

OPEN LEVER

DOOR OPEN

BUTTON

Figure D-1. Door sensing switch, monitor switch, third door switch and primary interlock switch

MONITOR SWITCH

The monitor switch is mounted on the middle position of latch hook. It is activated (the contacts opened) by the lower latch head while the door is closed. The switch is intended to render the oven inoperative by means of blowing the monitor fuse when the contacts of the relay RY1 and primary interlock switch fail to open when the door is opened.

Functions:

1.When the door is opened, the monitor switch contact close (to the ON condition) due to their being normally closed. At this time the door sensing and primary interlock and third door switches are in the OFF condition (contacts open) due to their being normally open contact switches.

2.As the door goes to a closed position, the monitor switch contacts are first opened and then the door sensing switch, third door switch and the primary interlock switch contacts close. (On opening the door, each of these switches operate inversely.)

3.If the door is opened, and the relay RY1 and the primary interlock switch contacts fail to open, the monitor fuse blows simultaneously with closing of the monitor switch contacts.

CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE TEST THE DOOR SENSING SWITCH, PRIMARY INTERLOCK SWITCH, RELAY(RY1) AND MONITOR SWITCH FOR PROPER OP- ERATION. (REFER TO CHAPTER “TEST PRO- CEDURE”).

NOTE: MONITOR FUSE AND MONITOR SWITCH ARE REPLACED AS AN ASSEMBLY.

THIRD DOOR SWITCH

The switch is activated by the latch heads, while the door is closed. When the door is opened, the switch interrupt the circuit to the power transformer. This switch prevents power transformer engaging and microwave when the door opened.

THERMISTOR

The thermistor is a negative temperature coefficient type. The temperature in the oven cavity is detected through the resistance of the thermistor, and then the control unit causes the heater relay to operate, thus the current to the heating element is turned ON/OFF.

MAGNETRON THERMAL CUT-OUT

The thermal cut-out located on the waveguide is designed to prevent damage to the magnetron if an over heated condition develops in the magnetron due to cooling fan failure, obstructed air guide, dirty or blocked air intake, etc. Under normal operation, the thermal cut-out remains closed. However, when abnormally high temperatures are reached within the magnetron, the thermal cut-out will open at 257οF (125οC) causing the oven to shut down. magnetron thermal cut-out is not reset at room temperature.

OVEN THERMAL CUT-OUT

The thermal cut-out located on the side of the steam duct is designed to prevent damage to the unit if the foods in the oven catch fire due to over heating produced by improper setting of cooking time or failure of control unit.

Under normal operation, the thermal cut-out remains closed. However, when abnormally high temperatures are reached within the oven cavity, the thermal cut-out will open at 302οF (150οC) causing the oven to shut down.

When the thermal cut-out has cooled, the thermal cut-out closes at 266οF (130οC)

CONV. THERMAL CUT-OUT

The thermal cut-out located on the left side of the thermal protection plate (left) is designed to prevent damage to the heater unit if an over heated condition develops in the tube due to cooling fan failure, obstructed air ducts, dirty or blocked air intake, etc.

Under normal operation, the thermal cut-out remains closed. However, when abnormally high temperatures are reached within the heater unit, the thermal cut-out will open at 302οF (150οC) causing the oven to shut down.

When the thermal cut-out has cooled, the thermal cut-out closes at 266οF (130οC)

HEATING ELEMENT

The heating element is located at the left side of the oven cavity. It is intended to heat air driven by the convection fan. The heated air is kept in the oven and force-circulated and reheated by the heating element.

CONVECTION COOKING SYSTEM

This oven is designed with a hot air heating system where food is not directly heated by the heating element, but is heated by forced circulation of the hot air produced by the heating element.

The air heated by the heating element is circulated through the convection passage provided on the outer casing of the