Troubleshooting - Honeywell 7800 Series Product Data

6. Loss of flame during RUN.
a. Open the main fuel manual shutoff valves. The
manual pilot shutoff valves must also be opened.
b. Depress the reset push button.
c. Start the system. Startup should be normal and the
main burner should light normally.
d. After the sequence is in the normal RUN period for
at least ten seconds with the main burner firing,
close the manual main and pilot fuel shutoff valve(s)
to extinguish the main burner flame.
e. The flame signal should drop below 1.25 Vdc within
.8 or 3 seconds (depending on the FFRT of the
amplifier) after the main flame goes out.
f. Safety shutdown will occur.
IMPORTANT
1. If the RM7896 fails to shut down on any of these
tests, take corrective action (refer to Troubleshooting,
RM7896 diagnostics and return to the beginning of
all Checkout tests).
2. When all Checkout tests have been completed, reset
all switches to original states.

TROUBLESHOOTING

RM7896 System Diagnostics
Troubleshooting control system equipment failures is easier
with the RM7896 self-diagnostics and first-out annunciation.
In addition to an isolated spst alarm relay (audible
annunciation), the RM7896 provides visual annunciation by
displaying the ALARM LED.
Self-diagnostics of the RM7896 enable it to detect and annunci-
ate both external and internal system problems. External faults
such as interlock failures, flame failures and false flame signals
are annunciated by the RM7896, which energizes the ALARM
LED or by using the optional Keyboard Display Module. The
7800 SERIES provides a System Annunciation Diagnostics and
Troubleshooting manual, form 65-0118.
The RM7896 provides diagnostic information to aid the
service mechanic to obtain information when troubleshooting
the system; see Table 6.
The optional Keyboard Display Module displays sequence
status messages indicating: STANDBY, PRE-PURGE, PILOT
IGN, MAIN IGN and RUN. The selectable messages also
provide visual indication, 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,
7800 SERIES RM7896A,B,C,D RELAY MODULE
most problems can be diagnosed without extensive trial and
error testing. Information available in the Diagnostic
Information file includes: Device Type, Device Suffix,
Software Revision, Manufacturing Code, Flame Amplifier
Type, Flame Failure Response Time, Selectable Jumper
Configuration Status, Run/Test Switch Status (RM7896C,D)
and Terminal Status.
Diagnostic Information Index
The RM7896 with the optional Keyboard Display Module can
monitor input/output terminals and can display the status of
the terminal at the VFD (for example; Pilot Valve T8 ON<);
see S7800A1001 Keyboard Display Module Specifications. A
complete terminal description and number are provided. 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 RM7896 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, and the fault message and burner status when the
fault occurred. The Historical Information can be viewed by
the optional S7800A1001 Keyboard Display Module
Specifications.
SERVICE
NOTE: A Lockout condition or restart of a RM7896 can be
accomplished by pressing the reset pushbutton on
the RM7896, or by pressing a remote reset
pushbutton wired through an optional Keyboard
Display Module, Data ControlBus Module™,
Extension Cable Assembly or Remote Reset Module.
A power-up reset will cause an electrical reset of the
RM7896 but will not reset a lockout condition.
SERVICE
NOTE: Remove the access slot covers on the sides of the
Q7800A,B to check voltages.
CAUTION
Reinstall access slot covers on the Q7800A,B
Subbase after performing voltage checks.
SERVICE
NOTE: Maximum ambient operating temperature of a
C7012E,F Series 1 through 6 will be reduced to
125°F because of the duty cycle operation of the
RM7896 Relay Module.
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65-0193