Troubleshooting - Honeywell RM7824A Product Data

d. Automatic pilot valve(s) should be energized but the
pilot cannot ignite.
e. Safety shutdown will occur.
3. Loss of flame during RUN.
a. Open the main fuel manual shutoff valve(s). The
manual pilot shutoff valve(s) must also be opened.
b. Depress the reset pushbutton.
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
three seconds after the main flame goes out.
f. Safety shutdown will occur.
IMPORTANT
1. 1.If the RM7824A fails to shut down on any of these
tests, take corrective action (refer to
Troubleshooting, RM7824A diagnostics and return to
the beginning of all Checkout tests).
2. 2.When all Checkout tests have been completed,
reset all switches to original states.

TROUBLESHOOTING

RM7824A System Diagnostics
Troubleshooting control system equipment failures is easier
with the RM7824A self-diagnostics and first-out annunciation.
In addition to an isolated spst alarm relay (audible
annunciation), the RM7824A provides visual annunciation by
displaying the ALARM LED.
Self-diagnostics of the RM7824A enable it to detect and
annunciate both external and internal system problems.
External faults such as flame failures and false flame signals
are annunciated by a lockout of the RM7824A that energizes
the ALARM LEDs by using the optional Keyboard Display
Module or 7800 SERIES System Annunciation Diagnostics
and Troubleshooting, form 65-0118.
The RM7824A provides diagnostic information to aid the
service mechanic to obtain information when troubleshooting
the system; see Table 7 and Table 8.
NOTE: Normal sequences are in bold type, while abnormal sequences are in standard type.
Sequence
INITIATE The LED indicates the burner status, POWER, which is a stabilization period for the RM7824A to check
for any fluctuations in dc voltage inputs or control input on power-up or during normal operation.
If the RM7824A is in a HOLD status, the following conditions could exist:
INITIATE HOLD The LED indicates the burner status, POWER, and that the RM7824A is waiting for excess line noise to
(Vdc Frequency/noise) clear up. The burner sequence will not advance into STANDBY until the excess line noise, which
prevents sufficient read of the voltage input, ceases.
INITIATE HOLD The LED indicates the burner status, POWER, and that DC Bus power has momentarily dropped out.
(AC LIne Dropout) The burner sequence will not advance into STANDBY until the DC Bus voltage has stabilized throughout
the INITIATE sequence.
Table 7. Sequence And Status Hold Information.
19
7800 SERIES RM7824A RELAY MODULE
The optional Keyboard Display Module displays sequence
status messages indicating: INITIATE, STANDBY,
SAFE-START CHECK, PILOT 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 and Diagnostic Information.
The Expanded Annunciator Terminal Status is not available
with the RM7824A. With this information, 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 and
Terminal Status.
Diagnostic Information Index
The RM7824A with the optional Keyboard Display Module can
monitor input/output terminals and can display the status of
the terminal at the VFD (e.g., Pilot Valve T9 ON<), see
S7800A Keyboard Display Module Specifications. A complete
terminal description and terminal 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 voltage is not
present at the terminal, OFF is displayed.
Historical Information
The RM7824A 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 S7800A Keyboard Display Module.
SERVICE NOTE: To check voltages, remove the access slot
covers on the sides of the Q7800A,B.
WARNING
Electrical Shock Hazard.
Can cause severe injury, death or property
damage.
To prevent accidental electrical shock or equipment
damage, reinstall access slot covers on the the
Q7800A,B Wiring Subbase after performing voltage
checks.
Information
65-0155—2