Interface Boards - Frymaster H50 Series Service And Parts Manual

the other leg of the heat relay coils, which then close electronic switches in the 24 VAC circuit to
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.

INTERFACE BOARDS

All fryers in this series have an interface board located in the component box located 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. The H50 Series of fryers has been in production since 1983.
Consequently, servicers are likely to encounter three different interface board designs. Although the
boards differ slightly in appearance, basic functioning and electrical connections are the same from
one to another. In the earlier design 806-3398 interface board (used between June 1996 and July
1999), the diagnostic LEDs are arrayed in a row across the bottom of the board as shown in the left-
hand illustration below. In later design 806-3398 interface boards (and in the 106-0396 interface
boards that replaced them in current production fryers), the LEDs (labeled D1 though D7) are
scattered around the board as shown in the right-hand illustration. The primary difference between
the earlier design boards and the later design boards is the combining of the separate blower motor
relay (K4) and the heat relays (K1 and K2) into a pair of replaceable relays (K2 and K3) in the latter.
Also, the 106-0386 interface board has an additional fuse located in the upper right hand corner.
Prior to June 1996, a board with replaceable relays very similar in appearance to the
was used. It is distinguished from the
NOTE: Although the printing on many boards indicates 2 Amp fuses, 3 Amp fuses (P/N
must be used.
SOUND
1
1
2
J2 2
GND
3
3
3 6 9 12
2 5 8 11
J1
1 4 7 10
K3 K4
GND
BLOWER
V2D
PWR
AD
HEAT
AS
RELAY
V2S
K1
1 2 6
GND GV PWR AL 12V AIR 24V AL PWR GV
EARLIER DESIGN INTERFACE BOARD P/N 806-3398
106-0386
GND
13
4 7 10
5 8 11 14
6 9 12 15
3 6 9 12
2 5 8 11
J3
1 4 7 10
K5
GND
V1D
MOTOR
RELAY
PWR
ALR
HEAT
V1S
RELAY
K2
3 4 5
GND
board by the absence of fuses.
SOUND
J2
1
2
GND
3
3 6 9 12
This Fuse is NOT
J1
2 5 8 11
present on 806-3398 IFB.
1 4 7 10
D1
GV
GND
V2D
PWR
AD
HEAT
AS
RELAY
D2 PWR
AND
V2S
BLOWER
MOTOR
RELAY
GND
LATER DESIGN INTERFACE BOARDS P/N 806-3398 and
1-2
106-0386
807-3843)
GND
1 4 7 10 13
F2 I g ni t ion
2 AMP Module
2 5 8 11 D6
14
15
3 6 9 12
12V
3 6 9 12
2 5 8 11
1 4 7 10
K1
D5
GV
Blower
Motor
2 Amp
K4
D3
HEAT
24V
RELAY
AND
D4
BLOWER
PWR
MOTOR
RELAY
GND
K2 K3
106-0386
board
D7
AIR
J3
GND
V1D
PWR
ALR
V1S