Modulating Gas Valve; Ignition Module - TurboChef 3240 Service Manual

To From
Primary Black White (240 VAC Input) 28.1
Black Blue (240 VAC Input)
Black Red (240 VAC Input)
Yellow Yellow
Secondary
Figure 33: Burner Transformer Ohm Chart
Combustion Blower
The combustion blower is a 3000 RPM, 208-
240 VAC, 0.33 A, 50/60 hz, blower motor.
The winding resistance is 92 W. The combus-
tion blower receives line voltage (208-240 VAC)
from the K3 relay. Once the combustion blower
reaches full speed, the air pressure switch closes,
applying 24 VAC to the ignition module.
Testing Procedure
1. Disconnect line voltage from the unit.
2. Take a resistance reading of the winding;
resistance should be 92 W. If resistance
is incorrect, the combustion blower is
damaged or defective and must be replaced
(page A-14).
3. Apply line voltage to the unit and check for
line voltage (208-240 VAC) applied to the
winding when the unit is calling for heat
and the K3 relay is closed.
4. If no voltage is present, inspect the wire
harness for damage or shorts (page 45).
5. If the wire harness is intact and undamaged,
the combustion blower is damaged or
defective and must be replaced (page A-14).

Modulating Gas Valve

The modulating gas valve is a combination gas
valve with a 24 VAC primary solenoid valve
and 0.1-10 VDC modulating valve. The
primary solenoid valve receives 24 VAC from
the ignition module. The resistance of the
primary solenoid valve is 535 k W. The
modulating valve receives 0.1-10 VDC from
the control board. The resistance of the
modulating valve is 44 W. The modulating
valve has an adjustment shaft that adjusts the
Expected Resistance
W
high and low flame pressure.
W
53.1
Testing Procedure
W
62.4
NOTE: See page 3 for instructions on adjusting
W
0.80
the high and low flame gas pressure.
1. Disconnect line voltage from the unit.
2. Take a resistance reading of both coils,
3. During warmup and cook mode, apply
4. If no voltage is present, inspect the wire
5. Check for 24 VAC leaving the ignition
6. If wire harness is intact and undamaged,

Ignition Module

The ignition module generates 30,000 V at the
spark igniter stud for direct ignition of the main
burner when 24 VAC is applied. The module
senses the presence of the burner flame and
discontinues the ignition spark.
If the burner fails to ignite within 6 seconds,
the module goes into safety lockout. If the
burner does not maintain 1.5 DC uA mini-
mum, the timed trial for ignition (6 seconds) is
repeated and safety lockout occurs. If safety
lockout occurs, power must be removed from
the module before it can be restarted.
Testing Procedure
NOTE: The ignition module is different in
domestic and international model ovens. Figure
34 shows the differences in the terminal labels
between the two models.
resistances should be 535k
W. If resistance is incorrect, the gas
valve is damaged or defective and must be
replaced (page A-14).
line voltage to the unit and check for 24
VAC at the primary solenoid coil and
0.1-10 VDC at the modulating valve coil.
harness for damage or shorts (page 45).
module (see Figure 35, page 28)
the modulating gas valve is damaged or
defective and must be replaced (Pipe and
valve assembly, page A-14).
W
and 44
2 7