If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-800-833-9353(WELD).

PROBLEMS
(SYMPTOMS)

POSSIBLE AREAS OF
MISADJUSTMENT(S)

RECOMMENDED
COURSE OF ACTION

FUNCTION PROBLEMS

The machine regularly overheats
and the yellow thermal light is ON
indicating a thermal overload.

1. The welding application may

be exceeding the
recommended duty cycle of the
V350-Pro.

2. Dirt and dust may have

clogged the cooling channels
inside the machine.

3. Air intake and exhaust louvers

may be blocked due to inade-
quate clearance around the
machine.

4. Make certain the fan as needed

(F.A.N.) is operating properly.
The fan should operate when
welding voltage is present
and/or when there is an over
temperature condition.

1. The 115VAC fan motor is

controlled by the control board
via the main switch board.
Perform the Fan Motor And
Control Test.

1. A thermostat or associated

circuitry may be faulty. See the
wiring diagram. One normally
closed thermostat is located on
the output choke and the other
is located on the main switch
board heat sink. See the wiring
diagram.

Note: The Main Switch Board

Removal Procedure will
be required to gain access
to the heat sink thermostat.

An attached wire feeder will not
function correctly.

1. Make certain the wire feeder

control cable is connected to
the correct 14-pin amphenol
type plug (115VAC or
24/42VAC) for the wire feeder
being used. See the
connection diagram.

2. Check the two circuit breakers

located at the rear of the
machine. Reset is tripped.

3. The wire feeder or control cable

may be faulty.

1. Perform the Auxiliary

Transformer Test.

2. Check the leads between the

14-pin amphenol type plugs
and the auxiliary transformer
for loose or faulty connections.

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