Troubleshooting & repair, Thermal protection ac trigger circuit (cont.), V300-pro – Lincoln Electric INVERTEC V300-PRO SVM105-B User Manual

Page 75

V300-PRO

TROUBLESHOOTING & REPAIR

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.

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

THERMAL PROTECTION AC TRIGGER CIRCUIT (cont.)

FIGURE F.21 - THERMAL PROTECTION AC TRIGGER CIRCUIT

CONTROL

BOARD

POWER

BOARD

11J4

EXTERNAL
TRIGGER

S4 OUTPUT
TERMINAL
SWITCH

FAN
THERMOSTAT

CHOKE
THERMOSTAT

PART OF 14 PIN

AMPHENOL

NORMALLY CLOSED

NOTE:

WHEN THERMOSTATS

TRIP, THE CIRCUIT

WILL BE OPENED

9J6

10J6

#210

4J2

#223A

#224

#503A

#503

#212B

#212A

#212C

#223B

#212D

VOLTS