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R7795A,B,C,D
TROUBLESHOOTING
3. If the voltage at terminals 16 and L1 are correct and
relay 3K does not pull in, replace the R7795.
B. Relay 3K pulls in but the burner motor does not start:
1. Check for power at terminal 8 when the 3K relay
pulls in.
a. If terminal 8 is not powered, replace the R7795.
b. If terminal 8 is powered, check the fan or burner
motor circuit and wiring.
C. Control locks out during prepurge:
If the flame indicator LED lights during the prepurge
period and remains lighted for six seconds or longer, the
control will lock out electrically (the device holds at the
start of prepurge with the blower energized). If the flame
on condition corrects itself after six seconds, the safety
switch will trip, causing a mechanical lockout. The line
voltage alarm (terminal 9) is energized and the burner/
blower (terminal 8) is de-energized. Check for a flame
simulating failure.
1. R7795B, D (rectification) models:
a. Disconnect flame circuit by inserting the plug end
of a meter jack or flame simulator into the flame
current jack on the front of the amplifier board. Do
not ground the other end of the plug or simulator.
b. Restart the system. If the flame indicator LED
lights, replace the R7795. If not, check the flame
detector and external flame detection circuit.
Look for light reaching the detector, hot refrac-
tory hold-in, defective wiring, or a defective
detector.
2. R7795A,C (ultraviolet) models:
a. Measure the flame current during prepurge. The
flame current should not exceed one-fourth mi-
croampere during the prepurge period.
b. If excessive flame current is present, check the
flame detector circuit for wiring problems. If no
wiring problems are found, replace the flame
detector. Recheck the flame current during
prepurge. If the excessive flame current persists,
replace the R7795.
D. Burner motor starts but prepurge does not stop at
the end of the purge timing (relay 1K does not pull in).
1. If the R7795 is an interrupted pilot model, check
that the RUN/TEST switch is in the RUN position.
2. Check the seating of the ST795A Purge Timer.
3. Check for line voltage on the airflow switch (termi-
nals 3 to L2).
4. Check the condition of the flame indicator LED. If
it is lighted, look for a flame simulating failure (see item
C above).
5. Replace the ST795A with one of the same timing. If
the problem still persists, replace the R7795.
E. Relay 1K pulls in but the pilot does not light, ignition
spark does not occur, or the pilot valve does not open.
1. Make sure that all manual fuel valves are opened.
2. Check the voltage at the pilot (or first stage oil) valve
terminal 5 and the ignition terminal 18. Check must be
made before device locks out.
3. If the voltage is zero, replace the R7795.
NOTE: If terminals 5 and/or 18 are shorted to L2, the
R7795 will be permanently damaged. This shorted con-
dition must be corrected before repowering the system.
4. If the terminals are powered, check the pilot and
ignition circuits for faulty wiring or defective devices.
F. Pilot lights but Flame Indicator LED does not come on.
1. Use the appropriate flame simulator (UV or recti-
fication) to check the Flame Indicator LED. Follow the
instructions supplied with the simulator.
2. If no simulator is available, check the flame current
as instructed on page 10. If the current is satisfactory,
replace the R7795. If the flame current is not satisfactory,
check the items listed in the Checkout section.
G. Pilot lights and Flame Indicator LED comes on but
the main burner does not light.
1. Check that the manual main fuel valves are open.
2. Check the voltage at terminal 6.
a. If the voltage is normal, check the main valve and
its external circuitry.
b. If the voltage is zero, replace the R7795.
NOTE: If any of the terminals are shorted to L2, the R7795
will be permanently damaged. This shorted condition
must be corrected before repowering the system.
H. Relay Flame Indicator LED remains on after the
flame goes out.
RECTIFICATION MODELS:
1. If the flame detector is a rectifying flame rod, install a
new R7795.
2. If the detector is a rectifying photocell or a C7012A,
plug the jack end of the flame simulator into the flame
current jack on the amplifier board.
a. If the flame indicator LED does not go out, re-
place the R7795.
b. If the flame indicator LED goes out, the trouble is
caused by hot refractory hold-in, detector failure
or other flame simulating conditions.
(1) Remove the flame simulating condition such
as false light.
(2) Resight the photocell to a cooler, more re-
mote area of the combustion chamber.
(3) Check the flame current as recommended in
the Checkout section. Replace the detector if
necessary.
(4) Check for a short or high resistance between
terminals F and G.
ULTRAVIOLET MODELS:
a. Remove any flame simulating condition such as
false light.
b. Resight the detector to a cooler, more remote area
of the combustion chamber.
c. Replace the detector if necessary.
d. Check for a short or high resistance between
terminals F and G.
18
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