Testing A Magnetron For An Open/Shorted Filament; Heating System, Speedcook Oven - TurboChef Residential Single and Double Wall Oven Service Manual

3. Disconnect the diode from the circuit.
4. Set the voltage meter to DC voltage and
connect it in series with the diode and a 9-volt
battery.
5. Connect one meter lead to one side of a 9-volt
battery and the other lead to one side of the
diode.
6. Connect the other side of the 9-volt battery to
the other side of the diode. DC voltage should
only be present on the meter in one direction.
7. Switch the meter leads on the diode, which will
cause the opposite reading to be visible. voltage
between 5-7 VDC should be present in only
one direction and 0-0.1 VDC in the other
direction, depending on the battery voltage.
Testing a High-Voltage Transformer
DANGER: Before replacing the transformer,
ensure the oven is removed from any power source.
Replacing this component while the oven is plugged
in can result in serious injury or death.
DANGER: Never attempt to measure the
secondary voltage values of the transformers when
they are enabled. Lethal voltage will be present.
1. Disconnect the power source and discharge the
high-voltage capacitors.
2. Disconnect all the wires on the transformer.
3. Use an ohmmeter to check primary winding,
secondary winding, and fi lament.
- Primary Side
240 VAC: Taps 1&3 = 1.4 Ω
208 VAC: Taps 1&2 = 1.2 Ω
- Secondary Side
240 & 208 VAC: Tap 4&Casing = 70.1 Ω
- Filament
240 & 208 VAC: Red Wires = 0.1 Ω

Testing a Magnetron for an Open/Shorted Filament

DANGER: Th e only safe way to test a
magnetron is by a resistance test of its fi lament.
Never attempt to measure the magnetron using any
other method while the microwave system is on.
Death or serious injury could occur.
1. Disconnect the power source and discharge the
high-voltage capacitors.
2. Isolate the magnetron from the circuit by
removing the wires from terminals F and FA.
3. An ohmmeter connected between the fi lament
terminals (F, FA) should indicate a reading of
less than 1 ohm.
4. A continuity check between either fi lament
terminal and the magnetron chassis should
indicate an infi nite resistance (open).
CAUTION: Be careful to not allow debris into
the waveguides when servicing the magnetrons.

Heating System, Speedcook Oven

Th e Speedcook oven heating elements require 208-
240 VAC to operate.
NOTE: Th e elements are voltage specifi c and cannot
operate properly without the correct voltage applied.
Confi rm incoming voltage matches the oven's
specifi cations (listed on the serial plate behind the
oven door).
When the CookWheel is turned to any of the seven
cooking cycles (except Favorites), the control board
sends voltage to activate the relays, which supply
power to the heating elements. L1 voltage for the
two primary elements are supplied through the K1
SSR and the L1 voltage for the preheat element is
supplied through the K8 relay (Gen 1) or preheat
relay 14 (Gen 2 relay board). Th e L2 voltage for all
three elements is supplied from the N.O. contact on
the K9 relay.
If the oven is not heating normally, see the below
troubleshooting options and use the one that best
describes the situation.
Th is section contains information on the following
topics:
- Heater element, Speedcook oven
- No heat
- Oven is heating up very slowly
- Testing for control voltage to the K1 SSR
- Testing for control voltage to the K8 relay
(Gen 1)
- Testing relay 14, preheat (Gen 2)
- Testing for a K9 relay that is stuck open
- Testing for a K1 SSR that is stuck open
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