Procedures for principal components test (1) – Merrychef 402s User Manual

Page 23

402s Ovens Pt. No. 32Z3522 Issue 6

1. Power Transformer Test

You will need:

A Digital Multi-meter (D.M.M.)
A Megger or similar resistance meter using 500V d.c.

PROCEDURES FOR PRINCIPAL COMPONENTS TEST (1)

Isolate the oven from the mains supply.

Ensure that the High Voltage Capacitor is discharged before commencing work.

Remove all connections from the Power Transformer.

Using a D.M.M., check the resistance of the windings. Results should be as follows:

Mains winding between tags

Approx. 1.1

High Voltage winding

Approx. 60

Filament winding
between terminals

Less than 1

Primary winding and chassis

Pass if over 10 M

Filament winding and chassis

Pass if over 10 M

5 Using a Megger, test the insulation resistance between:

One end of the High Voltage winding is connected to the
chassis, so this is not tested.

2. High Voltage Capacitor Test

You will need:

A Digital Multi-meter (D.M.M.)
A Megger or similar resistance meter using 500V d.c.

1. Isolate the oven from the mains supply.
2. Ensure that the High Voltage Capacitor is discharged before

commencing work.

3. Remove all connections from the High Voltage Capacitor.
4. Using a D.M.M., check for continuity between the terminals &

compare results with table on next page.

WARNING: High voltages and large currents are present at the High Voltage Capacitor. It is very

dangerous to work near this part when the oven is on. NEVER make any voltage

measurements at the High Voltage circuits, including the magnetron filament.

WARNING: Even when the oven is not cooking, the High Voltage Capacitor has High Voltages

present because of the Soft Start circuit. Isolate the oven before testing.

See Safety Code