TM 5-4520-253-13
TEST PC BOARD ASSEMBLY (CONT)
Table 4-3. PC Board Testing – Continued
(1)
Component Circuit
(2)
Heater Mode
(3)
Test For/
Meter
Setting
(4)
(5}
(6)
Meter
indi-
cation
Probe
Probe
NC. 1
No. 2
Disconnect fuel solenoid before performing following tests to
prevent fuel flow to burner and ignition. Set probes before
turning HEATER-OFF-FAN switch to HEATER.
EXTERNAL FUEL
PUMP RECEP-
TACLE
Power Cable:
Plugged
HEATER-OFF
FAN Switch:
HEATER
Voltage
Blue Wire
Green Wire
(14)
(15)
Terminal A
Terminal B
28 V dc
Carburetor
Power Cable:
Voltaqe
Orange Wire
White Wire
110 V ac
Heater/Carburetor
Thermostat
Plugged
HEATER-OFF-
FAN Switch:
HEATER
(16)
(17)
NOTE
Refer to lNSPECT/TEST/REMOVE/lNSTALL SAFETY
THERMOSTATS AND FLAME SWITCH AND BRACKET
ASSEMBLY, REMOVAL, page 3-105, to gain access to
thermostat wires.
Flame Switch and
Bracket Assembly
Power Cable:
Plugged
HEATER-OFF
FAN Switch:
HEATER
Voltage
110 V ac
Zero
Reading
Brown Wire
(18)
Red Wire
(19)
Flame Switch and
Bracket Assembly
Power Cable:
Plugged
HEATER-OFF
FAN Switch:
HEATER
Voltage
Violet Wire
(20)
Red Wire
(21)
Upper Thermostat
(Fan Side)
Power Cable:
Plugged
HEATER-OFF
FAN Switch:
HEATER
Voltage
Yellow Wire
(22)
110 V ac
Any White
Wire or
Terminal
Connector
4-30
