CB780/CB784 RELAY MODULES
19 32-00207—01
Fig. 17. CB780/CB784 sequence.
KEYBOARD DISPLAY MODULE (KDM)
The first line of the Keyboard Display Module provides
current status of the burner sequence (STANDBY, PURGE,
PILOT IGN, MAIN IGN, RUN and POST-PURGE), timing
information (PURGE, PILOT IGN, MAIN IGN and
POSTPURGE) in minutes and seconds, hold information
(PURGE HOLD: T19) and lockout information (Lockout,
Fault Code, Message and Sequence); see Fig. 19. The
extreme right side of the first line will either be blank or it
will show a small arrow pointing to the second line
followed by a two-letter code (DI-Diagnostic Information,
Hn-Fault History Information, and EA-Expanded
Annunciator). When the arrow and two-letter code are
displayed, it indicates the second line is showing a
selectable message submenu. The second line will display
selectable or preemptive messages. A selectable message
supplies information for flame strength, system status
indication, system or self-diagnostics and
troubleshooting. A preemptive message will have
parentheses around the message and supply a detailed
message to support the sequence status information. A
preemptive message can also be a lockout message. A
preemptive message will replace a selectable message to
support the sequence status information. It will also
replace a selectable message after 60 seconds if it or a
lockout message is available. The CB780/CB784 LEDs
provide positive visual indication of the program
sequence: POWER, PILOT, FLAME, MAIN and ALARM.
Fig. 18. Keyboard Display Module and
sequence status LEDs (Table 4).
NOTE: Normal sequences (in Table 4) are in BOLD TYPE,
while abnormal sequences are not in bold type.
CB780/CB784
POWER
00
VFD
DISPLAY
OPERATING
CONTROLS
AND
INTERLOCKS
BURNER
FLAME
SIGNAL
FIRING
RATE
MOTOR
INITIATE
POWER
STANDBY
POWER
PREPURGE
DRIVE TO
HIGH FIRE
POWER
PILOT
FLAME
MAIN
POWER
PFEP
4 OR 10 SEC
PILOT
FLAME
MAIN
POWER
MFEP
PILOT
FLAME
MAIN
RUN
POWER
POSTPURGE
POWER
STANDBY
00 00 10 25 00 1520
MOTOR OUTPUT SWITCHING
MOTOR ACTION
BURNER/BLOWER MOTOR
IGN.
15 SEC. PILOT
LIMITS AND BURNER CONTROLLER CLOSED
LOCKOUT INTERLOCKS CLOSED
PREIGNITION INTERLOCK CLOSED
LOW FIRE SW.
SAFE START CHECK
FLAME PROVING
10 SEC. IGN./PILOT
8
10
5
5 SEC.
21
6
TO
7TO
20TO
5
18
TO
13 15
TO
13
12
TO
M7411B
INTERLOCK CHECK
HIGH FIRE SW.
19
TO
13
14
TO
13
14
TO
5
4
6
L1
MAIN VALVE
9
TIMED
PURGE
POWER
FLAME
MAIN
PILOT
ALARM
POWER
FLAME
MAIN
PILOT
ALARMALARMALARMALARM
PREPURGE
DRIVE TO
LOW FIRE
00
LED
DISPLAY
IC
PII
SSC
833-2760 FIVE WIRE CONNECTOR FOR
COMMUNICATIONS, REMOTE KEYBOARD
DISPLAY AND REMOTE RESET
SEQUENCE
STATUS
SELECTABLE
MESSAGE OR
PREEMPTIVE
MESSAGE
SEQUENCE
STATUS
LEDs
RESET
PUSHBUTTON
FLAME
SIMULATOR INPUT
FLAME CURRENT
TEST JACKS
RUN/TEST SWITCH
DI = DIAGNOSTICS
H1 = HISTORY
EA = EXPANDED
ANNUNCIATOR
CAPTIVE
MOUNTING
SCREW
PLUG-IN
PURGE
CARD
KEYBOARD
DISPLAY
MODULE
RELAY
MODULE
FLAME
AMPLIFIER
M27264B
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