2-2 750-166
Historical Information Index
The CB780/CB784 retains historical information for
the six most recent lockouts. Each of the six lockout records
retain the cycle when the fault occurred, the hour of opera-
tion when the fault occurred, a fault code, a fault message and
burner status when the fault occurred; see Table 2.
SERVICE NOTE: The CB780 Relay Module will not
operate without a Keyboard Display Module or Control
Bus installed. (These devices are optional with CB784
control.)
SERVICE NOTE: If the Keyboard Display Module KDM
is scrambled, remove and remount the Keyboard Dis-
play Module, and reset the CB780/CB784 Relay Mod-
ule.
SERVICE NOTE: Reset the CB780/CB784 by pressing
the reset button on the CB780/CB784, or pressing a re-
mote reset pushbutton wired through the Keyboard Dis-
play Module or Control Bus. A power-up reset causes an
electrical reset of the CB780/CB784 but does not reset a
lockout condition.
SERVICE NOTE: Use the access slots on the sides of the
833-2725 wiring subbase to check terminal voltage.
SERVICE NOTE: Maximum ambient operating tempera-
ture of the 817-1121 UV self-check scanner, Series 1
through 6, is reduced to 125°F because of the duty cycle
operation of the CB780/CB784 Relay Module.
SERVICE NOTE: Configuration jumpers must be selected
prior to 200 hours of operation. If configuration jumpers
are changed after 200 hours, lockout 110 occurs.
TABLE 1—SEQUENCE AND STATUS HOLD MESSAGES FOR ALL CB780/CB784 CONTROLS.
NOTE: Normal sequences are in BOLD type, while abnormal sequences are not in bold type.
(Continued)
Sequence Burner Control Status
INITIATE mm:ss The KDM indicates the burner status, INITIATE, which is a stabilization period for the
CB 780/CB 784 to check for any fluctuations in ac line voltage on POWER UP or
control/recycle limit contact bounce during normal operation. The timing of the
INITIATE period is ten seconds before entering STANDBY.
INITIATE HOLD: AC
(ac Frequency/Noise)
The KDM indicates the burner status, INITIATE, and that it is waiting for excess line
noise to clear up. The burner sequence will not advance into STANDBY until the excess
line noise, which prevents sufficient reading of the line voltage inputs ceases or a line
frequency error is corrected (perhaps caused by using a 60 Hz device on a 50 Hz line, or
vice versa).
INITIATE HOLD: AC
(ac Line Dropout)
The KDM indicates the burner status, INITIATE, and that ac line power has momentarily
dropped out. The burner sequence will not advance into STANDBY until the ac line
voltage has stabilized throughout the INITIATE period.
INITIATE HOLD: AC
(ac Frequency)
The KDM indicates the burner status, INITIATE, and that line frequency is faster than
the expected value. The burner sequence will not advance into STANDBY until the line
frequency returns to the proper value (perhaps caused by using a 50 Hz device on a
60 Hz line).
INITIATE HOLD: AC
(Low Line Voltage)
The KDM indicates the burner status, INITIATE, and that low line voltage has occurred.
The burner sequence will not advance into STANDBY until the line voltage is at a
sufficient level for proper operating parameters.
STANDBY The KDM indicates the burner status, STANDBY. The burner can be placed in
STANDBY by opening the burner switch or if the operating controller indicates setpoint
has been satisfied. A demand could be present for burner operation, but the burner
sequence will not advance from STANDBY to PURGE until the recycle limits close. If
an Expanded Annunciator is connected, the display messages will be enhanced.
STANDBY HOLD: F/G
(Flame Detected)
The KDM indicates the burner status, STANDBY, and that a flame is detected. A
demand is present for burner operation. The burner sequence will not advanced to
prepurge because a flame is detected as being present. The sequence will not advance to
prepurge until the flame signal clears. If the flame signal does not clear within
40 seconds the CB 780/CB 784 will lockout.
STANDBY HOLD: T20
(Preignition Interlock)
The KDM indicates the burner status, STANDBY, and that the Preignition Interlock is
not closed. If a demand is present for burner operation, the burner sequence will not
advance to PREPURGE until the Preignition Interlock proves closed. If this time exceeds
a 30 second hold, the CB 780/CB 784 will lockout.
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