Troubleshooting - Honeywell 7800 Series Manual

d. Shutdown will occur after 15 minutes.
3. Loss of flame during RUN.
a. Open the pilot and main fuel manual shutoff
valve(s).
b. Start the system. Start-up should be normal and the
main burner should light normally.
c. 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 flame.
d. The flame signal should drop below 1.25 Vdc
RM7885A SYSTEM DIAGNOSTICS
Troubleshooting control system equipment failures is
easier with the RM7885A self-diagnostics and first-out an-
nunciation. It provides an isolated spst alarm relay (audible
annunciation) and also provides visual annunciation by dis-
playing the status LEDs.
Self-diagnostics of the RM7885A enable it to detect and
annunciate both external and internal system problems. Ex-
ternal faults such as flame failures and false flame signals are
annunciated by the RM7885A alarm output and energizing
the ALARM LED, or by using the optional Keyboard Dis-
play Module.
The RM7885A provides diagnostic information to aid the
service mechanic to obtain information when troubleshoot-
ing the system, see Table 6.
The optional Keyboard Display Module displays se-
quence status messages indicating: STANDBY, PILOT IGN
and RUN. The selectable messages also provide visual
indication, current status and historical status of the equip-
ment such as: Flame Signal, Total Cycles, Total Hours, Fault
History, Diagnostic Information and Expanded Annunciator
Terminal Status (if used). With this information, most prob-
lems can be diagnosed without extensive trial and error
testing. Information available in the Diagnostic Information
file includes: Device Type, Device Suffix, Software Revi-
sion, Manufacturing Code, Flame Amplifier Type, Flame
Failure Response Time, Selectable Jumper Configuration
Status and Terminal Status.
DIAGNOSTIC INFORMATION INDEX
The RM7885A with the optional Keyboard Display Mod-
ule can monitor input-output terminals and can display the
status of the terminal at the VFD (Pilot Valve T8 ON<), see
S7800A1001 Keyboard Display Module Specification. A
complete terminal description and terminal number is pro-
vided. The display will show the actual status of the terminal.
CHECKOUT • TROUBLESHOOTING
within .8 or 3 seconds (depending on the FFRT of
the amplifier) after the flame goes out.
e. The RM7885 will return to STANDBY and the
alarm will sound.
IMPORTANT:
1. If the RM7885A fails to shutdown on any of these tests,
take corrective action (refer to Troubleshooting,
RM7885A 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

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 RM7885A has nonvolatile memory that allows the
Relay Module to retain historical information for the six most
recent faults. 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.
SERVICE NOTE: A Lockout condition or restart of an
RM7885A can be accomplished by pressing the reset
pushbutton on the RM7885A, or by pressing a remote
reset pushbutton wired through an optional Keyboard
Display Module, DATA CONTROLBUS MODULE™
or Remote Reset Module. A power-up reset will cause an
electrical reset of the RM7885A 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 tempera-
ture of a C7012E,F Series 1 through 6 will be reduced to
125° F because of the duty cycle operation of the RM7885A
Relay Module.
29
RM7885A
65-0107