Frymaster Enodis MPH52/55 SERIES - Manual (Page 9)

1-2
provide current to the ignition module. Circuitry in the ignition module sends 24 VAC to the gas
valve via a normally closed high-limit switch (and, in fryers with built-in filtration systems, a
normally closed drain safety switch). Simultaneously, the module causes the ignitor to spark for 4
seconds to light the burner. A flame sensor verifies the burner ignition by measuring the flow of
microamps through the flame. If the burner does not light (or is extinguished), current to the
ignition module is cut, the gas valve closes, and the ignition module “locks out” until the power
switch is turned off and then back on. A 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 cut off current flow through the heat relay. This in turn cuts off the 24 VAC to
the ignition module, causing the gas valve to close.
1.1.2 Interface
Board
All fryers in this series have an interface board located in the component box behind the control
panel. The interface board provides a link between the controller/computer and the fryer’s individual
components without requiring excessive wiring, and allows the controller to execute commands
from one central point. This standard interface board is also used in a number of fryer types besides
the BIPH52/55 and MPH52/55 Series. The information contained in this section applies to
BIPH52/55 and MPH52/55 Series applications ONLY.
K2 and K3 are double-pole-double throw (dpdt) relays that supply 24VAC to the ignition and gas
valve circuits, as well as 120VAC to the blower motor. The relays on this board plug into sockets.
If a relay fails, that relay can be replaced.
LEDs (labeled D1 through D7) are arrayed around the board to assist in troubleshooting.
K4
K1
SOUND
1
2
3
GND
GND
V2D
PWR
AD
AS
V2S
GND
GV
PWR
12V
AIR
24V
PWR
GND
V1D
PWR
ALR
V1S
GV
GND
J2
INTERFACE BOARD P/N 106-0386SP
GND
J3
3 6 9 12
2 5 8 11
1 4 7 10
J1
3 6 9 12
2 5 8 11
1 4 7 10
15 12 9 6 3
14 11 8 5 2
13 10 7 4 1
K2 K3
HEAT
RELAY
AND
BLOWER
MOTOR
RELAY
D1
D2
D3
D4
D6
D7
Blower
Motor
2 Amp
D5
HEAT
RELAY
AND
BLOWER
MOTOR
RELAY
F 2 I g n i t i o n
2 AMP Module
D1 24 VAC to left gas valve (dual vat only)
D2 24 VAC to left ignition module
D3 24 VAC from transformer
D4 24 VAC to right ignition module
D5 24 VAC to gas valve (right valve if dual vat)
D6 12 VAC from transformer
D7 CE and Japanese units only: air sw itch closed
INTERFACE BOARD
LED DIAGNOSTIC LIGHTS
NOTE: Although the printing on some boards may indicate 2 Amp fuses, 3 Amp fuses (P/N
807-3843) must be used. In full-vat fryers, the relay for the left side (K2) may not be present.
The chart on the following page illustrates current flow through the board, and the table at the top of
page 1-4 identifies frequently used test points.