CB780E/CB784E RELAY MODULES WITH VALVE PROVING
750-234
45
32-00150—03
CB780/ECB784E System
Diagnostics
Troubleshooting control system equipment failures is
made easier with the CB780E/CB784E self-diagnostics
and first-out annunciation. In addition to an isolated spst
alarm relay (audible annunciation), the CB780E/CB784E
provides visual annunciation by displaying a fault code
and fault or hold message at the Keyboard Display
Module. The CB780E/CB784E provides118 diagnostic
messages for troubleshooting the system (see the
CB780E/CB784E System Annunciation Diagnostics and
Troubleshooting, Bulletin Number CB-7803.
Self-diagnostics of the CB780E/CB784E enables it to
detect and annunciate both external and internal system
problems. Internal faults and external faults such as
interlock failures, flame failures and false flame signals
are annunciated by the CB780E/CB784E, which
energizes the ALARM LED or visually displayed at the
Keyboard Display Module.
The KDM displays a sequence status message indicating:
STANDBY, PREPURGE, PILOT IGN, MAIN IGN, RUN and
POSTPURGE. The selectable messages also provide visual
indication of current status and historical status of the
equipment such as: Flame Signal, Total Cycles, Total
Hours, Fault History, Diagnostic Information and
Expanded Annunciator terminal status (if used). With this
information, most problems can be diagnosed without
extensive trial and error testing.
Table 10 provides the sequence and status hold
messages. Table 14
provides a summary of all
CB780E/CB784E fault messages and fault codes. In
addition, Diagnostic Information and History Data are
available to assist in troubleshooting the
CB780E/CB784E, see Table 12.
The CB780E/CB784E provides diagnostic information to
aid the service mechanic in obtaining information when
troubleshooting the system; see
Information available in the Diagnostic Information
includes Device Type, Device Suffix, Software Revision,
Manufacturing Code, Flame Amplifier Type, Flame Failure
Response Time, Selectable Jumper Configuration Status,
Run/Test Switch Status and Terminal Status.
Diagnostic Information Index
The CB780E/CB784E monitors input/output terminals
and can display the status of the terminal at the KDM
(example: Pilot Valve T8 ON<). See Table 11 for a complete
terminal description and number. The display will show
the actual status of the terminal. If voltage is detected at
the terminal, ON is displayed, but if no voltage is detected
at the terminal, OFF is displayed; seeTable 11.
Historical Information Index
The CB780E/CB784E has nonvolatile memory that allows
the Relay Module to retain Historical Information for the
six most recent lockouts. Each of the six lockout files
retains the cycle when the fault occurred, the hour of
operation when the fault occurred, a fault code, a fault
message and burner status when the fault occurred; see
Table 10.
SERVICE NOTE:
Reset CB780E/CB784E by pressing the reset pushbut-
ton on the CB780E/CB784E, or pressing a remote reset
pushbutton wired through the the 5-wire connector
(833-2760, ordered separately) on the Keyboard
Display Module or DATA CONTROLBUS MODULE™. A
power-up reset will cause an electrical reset of the
CB780E/CB784E but will not reset a lockout condition.
SERVICE NOTE:
If the Keyboard Display Module is
scrambled
, remove
and reinstall the Keyboard Display Module, and reset
the CB780E/CB784E Relay Module.
SERVICE NOTE:
Use the access slots on the sides of the Wiring Subbase
to check the terminal voltage of the CB780E/CB784E.
SERVICE NOTE:
Maximum ambient operating temperature of an 817-
1121 flame sensor, Series 1 through 6 will be reduced
to 125°F because of the duty cycle operation of the
CB780E/CB784E Relay Module.
Code 6-3
*Device
Specific*
Fault with special OEM
input circuits.
1.
Check wiring and operation of special OEM inputs.
2.
Reset and sequence the relay module.
3.
If fault reappears, remove power from the device, reapply power, then reset
and sequence the relay module.
4.
If the fault does not repeat on the next cycle, check for electrical noise
being copied into the relay module through the external loads or possibly
an electrical grounding issue.
5.
If the fault persists, replace the relay module.
Code 6-4
*Accessory
Fault*
VPS setup.
1.
Make sure Relay Module VP is programmed.
2.
T6 and T17 powered at the same time—correct wiring.
3.
Reset control if fault persists. Replace relay module.
Code 7-7
*Unused*
Unused at this time.
—
Table 14. Blinking Fault Codes and Recommended Troubleshooting. (Continued)
Blink Code
System Failure
Recommended Troubleshooting
