RM7838B, RM7838C 7800 SERIES RELAY MODULES
32-00211—01 22
— Some applications exist that do not use combus-
tion blowers, so power is available on terminal 7 at
the same time as terminal 6, either through lockout
interlock switches or just a jumper. For these appli-
cations leave JR3 intact (Disabled).
— Applications using the Combustion Blower (terminal
5) clip JR3. This enables the RM7838B,C to turn On
the Combustion Blower (terminal 5) 10 seconds after
the High Purge Switch (terminal 19) closes. When
the Combustion Airflow Switch closes, Valve Proving
testing will begin. The Combustion Blower (terminal
5) will be turned Off if time is still remaining on the
Purge timer.
SERVICE NOTE:Clipping and removing a site-configu-
rable jumper enhances the level of safety.
IMPORTANT
Clipping and removing a site-configurable jumper
after 200 hours of operation results in a
nonresettable Fault 110 and a lockout.
TROUBLESHOOTING
Troubleshooting can be accomplished by using the S7800
Keyboard Display Module (KDM) or a blinking POWER
LED.
The POWER LED provides fault identification when the
relay module locks out on an alarm. Fault identification is
a series of fast and slow blinking LED lights. The fast
blinks identify the tens portion of the fault code (three fast
blinks is 30), while the slow blinks identify the units
portion of the fault code (two slow blinks is 2). Three fast
blinks followed by two slow blinks would be fault code 32.
(See Table 9 for Blink Fault Code list.)
The LED code repeats as long as the fault exists. To clear
the fault, press the RESET button.
Use Table 9 to identify fault code numbers, possible
system failure and recommended troubleshooting
procedures.
Table 9. Blinking Fault Codes and Recommended Troubleshooting.
Blink Code System Failure Recommended Troubleshooting
Code 1-1
*Low AC Line
Voltage*
Low AC line detected. 1. Check the relay module and display module connections.
2. Reset and sequence the Relay Module.
3. Check the 7800 power supply and make sure that frequency and voltage
meet specifications.
4. Check the backup power supply, as appropriate.
Code 1-2
*AC Quality
Problem*
Excessive noise or
device running on
slow, fast, or AC line
dropout detected.
Code 2-1
*Unexpected
Flame Signal*
Flame sensed when no
flame is expected
during STANDBY or
PURGE.
1. Check that flame is not present in the combustion chamber; correct any
errors.
2. Make sure that the flame amplifier and flame detector are compatible.
3. Check the wiring and correct any errors.
4. Remove the flame amplifier and inspect its connections. Reseat the
amplifier.
5. Reset and sequence the relay module.
6. If the code reappears, replace the flame amplifier and/or the flame detec-
tor.
7. If the fault persists, replace the relay module.
Code 2-2
*Flame Signal
Absent*
No-flame time present
at the end of the PIlot
Flame Establishing
Period; lost during the
Main Flame
Establishing Period or
during RUN.
1. Measure the flame signal. If one exists, verify that it meets specifications.
2. Make sure that the flame amplifier and flame detector are compatible.
3. Inspect the main fuel valve(s) and valve connection(s).
4. Verify that the fuel pressure is sufficient to supply fuel to the combustion
chamber. Inspect the connections to the fuel pressure switches. Make
sure they are functioning properly.
5. Inspect the Airflow Switch and make sure that it is functioning properly.
6. Check the flame detector sighting position; reset and recycle. Measure the
flame signal strength. Verify that it meets specifications. If not, refer to the
flame detector and/or flame amplifier checkout procedures in the instal-
lation instructions.
7. Replace the flame amplifier and/or the flame detector, if necessary.
8. If the fault persists, replace the relay module.
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