Troubleshooting - Honeywell 7800 Series Manual

RM7800E,G,L,M

TROUBLESHOOTING

RM7800 SYSTEM DIAGNOSTICS
Troubleshooting control system equipment failures is
made easier with the RM7800 self-diagnostics and first-out
annunciation. In addition to an isolated spst alarm relay
(audible annunciation), the RM7800 provides visual annun-
ciation by displaying a fault code and fault or hold message
at the Keyboard Display Module 2 row by 20 column VFD.
The RM7800 provides 118 diagnostic messages for trouble-
shooting the system (see 7800 SERIES System Annuncia-
tion Diagnostics and Troubleshooting, form 65-0118).
Self-diagnostics of the RM7800 enables it to detect and
annunciate both external and internal system problems. Inter-
nal faults and external faults such as interlock failures, flame
failures and false flame signals are annunciated by the
RM7800, which energizes the ALARM LED or visually
displayed at the Keyboard Display Module VFD.
The VFD 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 An-
nunciator terminal status (if used). With this information,
most problems can be diagnosed without extensive trial and
error testing.
Table 3 provides the sequence and status hold messages.
Table 9 provides a summary of all RM7800 fault messages
and fault codes. In addition, Diagnostic Information and
History Data are available to assist in troubleshooting the
RM7800, see Table 5.
The RM7800 provides diagnostic information to aid the
service mechanic in obtaining information when trouble-
shooting the system, see Tables 3, 4, 5 and 9. 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.
Troubleshooting
Diagnostic Information Index
The RM7800 monitors input/output terminals and can
display the status of the terminal at the VFD (example: Pilot
Valve T8 ON<). See Table 4 for a complete terminal descrip-
tion 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, see Table 4.
Historical Information Index
The RM7800 has nonvolitile 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 4.
IMPORTANT: The RM7800 will not operate without a
Keyboard Display Module, Extension Cable Assem-
bly or a DATA CONTROLBUS MODULE™ installed.
SERVICE NOTE: If the Keyboard Display Module VFD
is scrambled, remove and reinstall the Keyboard Display
Module, and reset the 7800 SERIES Relay Module.
SERVICE NOTE: Reset RM7800 by pressing the reset
pushbutton on the RM7800, or pressing a remote reset
pushbutton wired through the Keyboard Display Module,
DATA CONTROLBUS MODULE™ or Remote Reset
Module. A power-up reset will cause an electrical reset of
the RM7800 but will not reset a lockout condition.
SERVICE NOTE: Use the access slots on the sides of the
Q7800A,B to check terminal voltage.
SERVICE NOTE: Maximum ambient operating tem-
perature of a C7012E,F, Series 1 through 6 will be
reduced to 125° F because of the duty cycle operation of
the RM7800 Relay Module.
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