Troubleshooting - Honeywell 7800 Series Manual

TROUBLESHOOTING

RM7800 Series System Diagnostics
Troubleshooting control system equipment failures is made
easier with the RM7800 SERIES self-diagnostics and first-out
annunciation. In addition to two isolated spst alarm relays
(audible annunciation), the RM7800 SERIES provides visual
annunciation by displaying a fault code and fault or hold
message at the Keyboard Display Module 2 row by 20
column VFD. The RM7800 SERIES provides 61 diagnostic
messages for troubleshooting the system (see the attached
list in Table 8).
Self-diagnostics of the Relay Module enable 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
Relay Module, which energizes the ALARM LED, or visually
displayed at the Keyboard Display Module VFD.
The Keyboard Display Module displays a sequence status
message indicating: STANDBY, PURGE, PREIGNITION,
SAFETY1, PILOT STAB., MAIN TRIAL, 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 and Diagnostic Information. With this
information, most problems can be diagnosed without
extensive trial and error testing.
Table 5 provides the sequence and status hold messages.
Table 8 provides a summary of all Relay Module fault
messages and fault codes. In addition, Diagnostic Information
and History Data are available to assist in troubleshooting the
Relay Module; see Table 6.
The Relay Module provides diagnostic information to aid the
service mechanic in obtaining information when
troubleshooting the system; see Tables 5, 6, and 8.
Information available in the Diagnostic Information includes
Device Type, Device Suffix, Software Revision (Display/Relay
Module), Manufacturing Code, Flame Amplifier Type, Flame
Failure Response Time, Selectable Jumper Configuration
Status, Run/Test Switch Status and Terminal Status.
7800 SERIES RM7830A, RM7850A RELAY MODULE
Diagnostic Information Index
The Relay Module monitors input/output terminals and can
display the status of the terminal at the Keyboard Display
Module (example: Pilot Valve T8 ON). See Table 6 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.
Historical Information Index
The Relay Module has nonvolatile memory that allows it 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 6.
SERVICE NOTE: If the Keyboard Display Module is
scrambled , remove and reinstall the
Keyboard Display Module, and reset the
RM7800 SERIES Relay Module.
SERVICE NOTE: Reset the Relay Module by pressing the
reset pushbutton on the Relay Module, or
pressing a remote reset pushbutton wired
through the Keyboard Display Module,
DATA CONTROLBUS MODULE™ or
Remote Reset Module. Note that Remote
Reset is subject to application approval. A
power-up reset will cause an electrical
reset of the Relay Module but will not
reset a lockout condition.
SERVICE NOTE: Use the access slots on the sides of the
Q7800A to check terminal voltage.
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