Service manual

402s Ovens Pt. No. 32Z3522 Issue 6
4
This manual is designed to assist engineers who have been on a recognised product familiarisation
and training course run by Merrychef. It has been prepared to offer technical guidance for the 402s
range of Ovens.
Please remember that it is wiser not to attempt a service task if you are unsure of being able to
complete it competently, quickly, and above all safely.
To avoid injury to yourself, and to protect the appliance from possible damage, please follow this
Safety Code when servicing these ovens.
Before attempting to repair the oven, check it for microwave emission using a calibrated
emission detector.
Check that the oven is not emitting microwaves, even when supposedly not in operation.
Check that the oven is not operating continuously, whether the display indicates cooking or
not.
Always discharge the HT capacitors before working on the oven using a suitably insulated
10 MΩ Resistor.
When testing the oven with covers off run for short periods of time only or magnetrons will
overheat and the display will show Error condition.
Before removing any covers from the oven, do all of the following.
• Switch off the mains supply and remove the plug from the wall socket.
or
• If the oven is hard wired, ensure that the power is turned off at the isolator switch.
Note:
The On/Off switch on the oven is not adequate protection against electric
shock, as it does not isolate all of the internal wiring from the mains.
Upon completion of a service the oven, or before reconnecting the appliance to the electrical
supply for testing, check all of the following points:
• All internal electrical connections are correct (see wiring diagrams).
• All wiring insulation is correct and is not touching a sharp edge.
• All grounding connections are electrically and mechanically secure.
• All door safety interlocks are secure and mechanically sound.
• The door operation is smooth, and the arms run freely in the slots.
• The door activates all four of the door interlock switches and in the correct order
• The temperature sensor is correctly connected to the Power PCB.
Before finishing a service call, recheck the following points:
• All of the electronics are functioning correctly and all of the touch pads are working.
• Microwave emissions are below permissible limit of 4 mW/cm².
• The power output of the oven is checked in accordance with the procedure page.
• Oven has correct 2 inch ( 50mm ) air gap all round and 2 inches ( 50mm ) above.
Air flow should not be restricted.
SAFETY CODE