Welbilt Frymaster FPLHDC265 Service And Parts Manual page 6

HIGH EFFICIENCY DECATHLON FPLHDC65 GAS FRYERS
CHAPTER 1: SERVICE PROCEDURES
Electronic Ignition Configuration
(cont.)
At start-up the ON/OFF switch is placed in the ON position, supplying 12 VDC to the heat
control circuitry in the controller or controller and to one side of the heat relay coil on the
interface board. If resistance in the temperature probe indicates the temperature in the frypot
is below 180°F (82°C), the current flows through a melt cycle circuit where a timer switch
alternately closes for 3 seconds and opens for 24 seconds. If the temperature is 180°F (82°C)
or above, the current flows through a heat circuit, bypassing the timer switch. In either case,
current is supplied to the other leg of the heat relay coil which then closes an electronic switch
in the 24 VAC circuit to provide current to the ignition module. NOTE: The listed melt cycle
times and exit temperature pertain to the Compu-Fry controller only.
Circuitry in the ignition module sends 24 VAC current to the gas valve via a normally closed
high-limit switch and a drain safety switch. Simultaneously, the module causes the ignitor to
spark for up to 90 seconds to light the pilot flame. A flame sensor verifies that the pilot is lit by
measuring the flow of microamps through the flame. If the pilot does not light (or is
extinguished), current to the ignition module is interrupted, preventing the main valve from
opening, and the ignition module "locks out" until the power switch is turned OFF, then back
ON.
A temperature probe monitors the temperature in the frypot. When the programmed setpoint
temperature is reached, resistance in the probe causes the heat cycle circuitry in the controller
to interrupt current flow through the heat relay. This in turn interrupts the 24 VAC current to
the ignition module, resulting in closure of the gas valve.
NOTE: Unlike previous modules, microamp readings on these black modules will move up and
down as the module pulses on and off and this is an indication that the module is functioning.
Control Options
LHDC Series gas fryers may be equipped with Thermatron controls, Compu-Fry controllers, 3-
Lane controllers or FAST controllers.
In fryers equipped with Thermatron controls, the fryer is turned on and off by means of a
rocker switch and the temperature is set by adjusting a potentiometer. An interface board is
located in the component box (shield) behind the control panel (controller-equipped) or a
Thermatron board is located in a component box inside the cabinet (Thermatron-equipped).
Interface Boards
The interface board provides a link between the controller/controller and the fryer's individual
components without requiring excessive wiring and allows the controller to execute
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