147
Table 103 — IGC Board Inputs and Outputs
CURRENT SENSOR BOARD (CSB) — This board moni-
tors the status of the compressor by sensing the current flow to
the compressors and then provides digital status signal to the
MBB and CXB.
TIMER RELAY CONTROL BOARD (TR1) — The TR1 is
used on modulating gas heat equipped units only. It is located
in the gas heat section and is used in combination with the
SC30 to provide control of the modulating gas heat section.
The TR1 receives an input from the IGC, initiates a start-up se-
quence, powers the SC30, sets the induced-draft motor speed,
and provides the main gas valve high fire input. When the start-
up sequence is complete, the TR1 checks the input from the
SC30 to determine which state to command the induced-draft
motor and main gas valve. See Table 104 for TR1 inputs and
outputs. The TR1 has status LEDs on the front cover. See
Table 105 for TR1 status LED descriptions.
Table 104 — TR1 Board Inputs and Outputs
Table 105 — TR1 Status LEDs
SIGNAL CONDITIONER CONTROL BOARD (SC30) —
The SC30 is used on modulating gas heat equipped units only.
It is located in the gas heat section and is used in combination
with the TR1 to provide control of the modulating gas heat
section. The SC30 is powered by an output from the TR1. It
receives a capacity input from the SCB, provides a capacity
output to the modulating gas valve, and provides an output to
the TR1 to determine which state to command the induced-
draft motor and main gas valve. See Table 106.
Table 106 — SC30 Board Inputs and Outputs
NAVIGATOR™ DISPLAY — This device is the interface
used to access the control information, read sensor values, and
test the unit. The Navigator display is a 4-line, 20-character,
LCD display as well as an Alarm Status LED. See Fig. 38. The
display is easy to operate using 4 buttons and a group of 11
LEDs that indicate the following menu structures:
• Run Status
• Service Test
• Temperatures
•Pressures
• Set points
• Inputs
• Outputs
• Configuration
• Timeclock
• Operating Modes
•Alarms
The RXB and EXB boards contain a second LEN port that
can be used with the handheld Navigator display.
CONTROL MODULE COMMUNICATIONS
Red LED
— Proper operation of the control boards can be vi-
sually checked by looking at the red status LEDs as shown on
Fig. 34-37. When operating correctly, the red status LEDs
should blink in unison at a rate of once every 2 seconds. If the
red LEDs are not blinking in unison, verify that correct power
is being supplied to all modules. Also, be sure that the main
base board is supplied with the current software and that all
boards are configured on. If necessary, reload current software.
If the problem still persists, a board may need to be replaced. A
POINT NAME POINT DESCRIPTION
CONNECTOR
PIN NO.
INPUTS
RT 24 Volt Power Supply RT,C
W Heat Demand 2
GFan 3
LS Limit Switch 7,8
RS Rollout Switch 5,6
SS Hall Effect Sensor 1,2,3
CS Centrifugal Switch (Not Used) 9,10
FS Flame Sense FS
OUTPUTS
CM Induced Draft Motor CM
IFO Indoor Fan IFO
R 24 Volt Power Output (Not Used) R
SPARK Sparker —
LED Display LED
TERMINAL TYPE OF I/O RESULT/ACTION
INPUTS
1, 2
24 Vac Input
Powers TR1
3, 4
5 Not Used Not Used
6
24 Vac Input
from SC30
Starts Timer no. 2
IDM2 Runs at High Speed
MGV2 Operates in High Fire
7
24 Vac Input
from IGC2
Starts Timer no. 1
IDM2 Runs at High Speed
MGV2 Operates in Low Fire
Terminal 6 Input ignored during
duration of Timer no. 1
OUTPUTS
8, 9 Relay Output MGV2 Operates in High Fire
10, 11 Relay Output Powers SC30
12, 14 Relay Output IDM2 Runs at High Speed
13, 14 Relay Output IDM2 Runs at Low Speed
LED NAME POINT DESCRIPTION
ON Power
SR Start relay during timer no. 1 duration
MR Modulating relay - lit after timer no. 1 times out
FR
Fan relay - lit when inducer fan runs on high
speed
CR
Control relay - lit when gas valve is in high pres-
sure stage.
TERMINAL TYPE OF I/O RESULT/ACTION
INPUTS
1
24 Vac Input
from TR1
Powers SC30
2
7
4-20 mA Input
from SCB
Sets Output to Modulating Gas
Valve
8
OUTPUTS
3
0-20 Vdc Output
Output to Modulating Gas Valve
4
5, 6 Relay Output Starts TR1 Timer no. 2
Ru
n Sta
tu
s
S
e
rv
ice
Te
s
t
T
em
p
era
ture
s
P
res
s
ure
s
S
e
tpo
in
ts
In
pu
ts
O
utp
uts
C
on
fig
u
ra
tion
T
im
e
Clo
ck
O
p
er
ating
M
od
es
A
la
rm
s
E
N
T
E
R
E
S
C
M
O
D
E
Ala
rm
St a
tus
T
IM
E
E
W
T
L
W
T
S
E
T
P
1
2
.
5
8
5
4
.
6
F
4
4
.1
F
4
4
.
0
F
N
A
V
I
G
A
T
O
R
C
o
m
f
o
r
t
L
in
k
Fig. 38 — Accessory Navigator Display
To Next Page
Loading...
