Lincoln Electric INVERTEC V300-PRO SVM105-B Service Manual page 75

F-45
THERMAL PROTECTION AC TRIGGER CIRCUIT (cont.)
FIGURE F.21 - THERMAL PROTECTION AC TRIGGER CIRCUIT
T1
EXTERNAL
TRIGGER
#212C #212A
2 C
4 D
#223B
PART OF 14 PIN
AMPHENOL
4. Locate the Auxiliary Transformer T1 and leads used
for test. See Figure F.21.
5. Turn main power ON.
6. Test Auxiliary Transformer voltage for 24 VAC
between leads 503 and 212D. See Figure F.21.
a. If 24 VAC is present, transformer is OK. Go to
step 7.
b. If 0 VAC is present, test input voltage to Auxiliary
Transformer.
c. If input voltage to Auxiliary Transfor-mer is cor-
rect, replace Auxiliary Transformer.
d. If input voltage to Auxiliary Transfor-mer is not
correct, check Line Switch S12 and connecting
leads.
TROUBLESHOOTING & REPAIR
#503
24
VOLTS
AC
10J6
#212D
POWER
BOARD
#212B
9J6
S4 OUTPUT
TERMINAL
SWITCH
#223A
V300-PRO
CHOKE
THERMOSTAT
#503A #224
NORMALLY CLOSED
NOTE:
WHEN THERMOSTATS
TRIP, THE CIRCUIT
WILL BE OPENED
CONTROL
11J4 4J2
BOARD
7. Check that Output Terminal Switch S4 is in the ON
position (closed).
8. Test for 24 VAC between leads 223A and 210.
a. If 24 VAC is present, then AC Trigger Circuit is
functioning normally.
b. If 0 VAC is present, check Choke Thermostat
and Fan Thermostat.
F-45
FAN
THERMOSTAT
#210