The Control System; Control Board; Display; Display Emi Filter - TurboChef 3240 Service Manual

The Control System

This section contains information about the
following components:

-Control Board

-Display

-EMI Filter

-Fuses

-High-limit Thermostat

-Idle Button

-Keypad

-Power Supply - 24VDC (Domestic)

-Power Supply - 24VDC (International)
-Relay (K3 - Gas)
-Relay (K4 - Ignition)
-RTD
-Smart Card Reader
-Speaker
-Thermostat - 120 º F (Close on Rise)
-Wire Harness
This section also contains testing procedures for
the following components:
-Power Supply - 24VDC (Domestic)
-Power Supply - 24VDC (International)
-Relay (K3 - Gas)
-Relay (K4 - Ignition)
-RTD
Control Board
The control board is powered by the 24 VDC
power supply, and sends control voltage to all
the relays. See page 45 for a schematic. 24
VDC can be measured at the J9 connector, pins
19 and 8. See pages 45-47.
Display
The vacuum fluorescent display is the primary
user interface, and is powered by the control
board using 5 VDC. Its input voltage can be
tested at J7, pins 1 and 3 (page 45).
EMI Filter
The EMI filter helps suppress the amount of
RF "noise" emitted by the oven, also filtering
noise from entering the controls.
Fuses
The control circuit is ultimately protected by
two 20-amp class CC fuses, which are in the
line-voltage circuit (incoming voltage). The
fuses are designed to blow in case of an over-
current situation.
High-Limit Thermostat
The high limit thermostat is a 3-pole, manual
reset thermostat with a trip point of 572ºF
(300ºC). The thermostat interrupts power to
both the ignition module and the closed circuit
of the I/O control board.
Idle Button
The Idle Button places the oven in idle mode,
slowing the blowers to 30%. When lit, idle
mode is active.
Keypad
The keypad is an 11-key membrane switch.
Power Supply - 24VDC (Domestic)
The power supply - 24VDC (domestic) con-
verts line voltage (208-240 VAC) to 24 VDC.
Line voltage (208-240 VAC) is connected to
terminals 1 & 4 (jumper between terminals 2
& 3, terminal 5 is not used). The resistance
from terminals 1 to 4 (with wires disconnected)
is 20.7 W. The output (24 VDC) is on
terminals "+OUT" (power = good) and "-
OUT" (power = bad).
Testing Procedure
1. Disconnect line voltage from the unit.
2. Take a resistance reading on terminals
1 & 4.
a) If terminal resistance is correct
(20.7 W):
-Apply line voltage to the unit.
-Check for line voltage (208-240 VAC)
-at terminals 1 & 4.
2 1