S89E,F DIRECT SPARK IGNITION CONTROL MODULE
68-0066—05
10
Measure Flame Current
The S89 provides ac power to the flame sensor which the
flame rectifies to direct current. If the flame signal back to the
S89 is less than 0.8
μ
A, the S89 will shut down the system.
To measure the flame current:
1.
Connect a meter, set to the dc microammeter scale, in
series with the flame sensor as shown in Fig. 6. Use the
W136 Test Meter or equivalent. Connect the meter as
follows:
a. Disconnect the sensor lead at the S89.
b. Connect the red (positive) meter lead to the S89
sense terminal.
c. Connect the black (negative) meter lead to the free
end of the sensor lead.
2.
Restart the system and read the meter. The flame
sensor current must be at least 0.8
μ
A and steady.
3.
If the meter reads less than 0.8
μ
A or reading is
unsteady, recheck points under Check Flame Sensor
and Igniter, above.
Fig. 6. S89 flame current measurement.
Fig. 7. Check burner flame condition.
GND (BURNER)
24V (GND)
24V
VALVE
VALVE (GND)
SENSE
TO
SENSOR
BLACK
(–)
RED (+)
M19840
FLAME SENSOR CURRENT CHECK–USE µA SCALE
0.8 µA DC MINIMUM
(AND STEADY)
DISCONNECT
WIRE FROM
SENSE
TERMINAL
W136 (OR EQUIV.)
MULTIPURPOSE METER
CHECK BURNER FLAME CONDITION
NOISY LIFTING FLAME
BURNER
WAVING FLAME
SMALL BLUE FLAME
LAZY YELLOW FLAME
GOOD RECTIFYING FLAME
1 IN. (25.4 MM)
1/4 TO 1/2 IN. (6.4 TO 12.7 MM)
M18055
CHECK FOR:
• HIGH GAS PRESSURE
• EXCESS PRIMARY AIR
OR DRAFT
CHECK FOR:
• POOR DRAFT
• EXCESS DRAFT
• HIGH VELOCITY OR
SECONDARY AIR
INSTALL SHIELD IF NECESSARY.
CHECK FOR:
• CLOGGED PORTS OR
ORIFICE FILTER
• WRONG SIZE ORIFICE
CHECK FOR
LACK OF AIR FROM:
• DIRTY PRIMARY
AIR OPENING
• LARGE PORTS
OR ORIFICES
