Turbo Chef Technologies Residential Single and Double Wall Oven High-Voltage Transformers

When the high-voltage winding starts to go toward negative, the high-voltage diode becomes non-conducting with the charged high voltage capacitor in series with the high-voltage winding. When the transformer gets to its negative peak of -2400, the voltage applied to the filament is negative 4000+ volts.

High-Voltage Transformers

The high-voltage transformers are ferro-resonant, limiting fault currents and minimizing magnetron power changes due to input voltage changes. The high-voltage transformer supplies the high voltage for the Voltage Doubler Circuit. For Gen 1 ovens, they are controlled via the K3 and K4 relays. For Gen 2 ovens, they are controlled by relays 2 and 3 on the relay board (outputs RBJ5 and RBJ4).

Wiring a High-Voltage Transformer

DANGER: Never attempt to wire or measure the secondary voltage values of the high-voltage transformers with the high-voltage transformers enabled. Lethal voltage will be present.

The proper re-installation of a high-voltage transformer is critical. Upon removing a high-voltage transformer, make sure to note where each wire was connected. Refer to the oven schematic (Section 7) detailing the proper wiring.

As shown in the schematic, transformers are installed mirror opposite and wired 180° out-of-phase. It is essential for longevity that the high-voltage transformers remain 180° out-of-phase. This can be checked by placing a volt meter across terminals T1-1 and T2-1 (primary voltage). If the meter reads 0 VAC, the high-voltage transformers are most likely wired in-phase.

As a last check, energize the microwave system and verify the voltages between the incoming voltage taps on each high-voltage transformer. Taps 1 and

2 = 208V. Taps 1 and 3 = 240V. Wiring issues must be corrected prior to returning the oven to service. Voltage at the wall must match the transformer configuration.

Magnetrons

The magnetron generates microwave energy by means of 4000+ volts supplied by the microwave circuit. Due to the very high voltage present during operation, the only safe way to test this component is by a resistance test of its filament with the power disconnected and the capacitors properly discharged.

The magnetron can have a good filament and still not operate properly. All of the testing should be completed on the other microwave components first before checking the magnetron. If all tests listed

in this manual are completed for the transformer, diode, and capacitor, and all show to be within specifications, the magnetron will be the defective component.

CAUTION: Be careful to not allow debris into the waveguides when servicing the magnetrons.

Stirrer Motor and Assembly

The stirrer is responsible for evenly distributing hot air and microwaves that are launched from the top of the oven into the cook cavity. The stirrer is driven by a motor that remains on during a cook cycle. When the oven is cooling down, the stirrer motor turns off when the cook cavity temperature recedes below 160°F (71°C).

To visually test stirrer motor operation, go to Bake, which will automatically turn on the stirrer, the stir- rer is visible through the upper jetplate holes.

Waveguides

The waveguides channel microwaves into the cook cavity. To prevent the life of the magnetrons from being shortened, be careful to not allow debris to enter into the waveguides when servicing the magnetrons.

5.7

OVEN SYSTEMS