Troubleshooting & repair – Lincoln Electric POWER MIG SVM160-B User Manual

Page 92

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TROUBLESHOOTING & REPAIR

F-48

F-48

POWER MIG 300

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MAIN TRANSFORMER AND OUTPUT CHOKE REMOVAL AND

REPLACEMENT

(continued)

LEAD DISCONNECTION

8. Using a phillips head screwdriver, remove fan lead

X4 from fan relay terminal #1 and disconnect fan
lead X3 from its in-line connector at the fan motor.
Cut cable ties as needed pull the leads through the
baffles to clear them.

9. Using a 1/2 in. wrench, disconnect leads X1 and X2

from the output rectifier. Note the order of the fas-
teners for reassembly: bolt, flat washer, heavy
lead, terminal, lock washer, nut.

10. Disconnect leads X5 and X6 from the control recti-

fier (spade connectors).

11. Disconnect thermostat leads 502 and 503A from

their in-line connectors (right side of the machine).

12. Using a 3/8 in. nutdriver, disconnect leads H2, H3,

and H5 from the reconnect panel terminals 2, 3,
and 5.

13. Using a 3/8 in. driver, disconnect leads H1 and H4

from the back of the line switch. Looking at the
back of the switch, H1 is at the bottom right and H4
is at the bottom left. Note that leads H1 and H4,
which go to the reconnect panel, attach at these
same terminals.

14. Using a 1/2 in. wrench and socket wrench, discon-

nect heavy lead B2 from the choke.

15. Using a 9/16 in. wrench and socket wrench, dis-

connect the heavy lead from the choke to the pos-
itive output terminal. It is not necessary to remove
any other leads; screw the bolt with leads still
attached back into the positive output terminal until
reassembly.

MAIN TRANSFORMER AND CHOKE
ASSEMBLY REMOVAL

16. Using a 1/2 in. socket wrench, remove 4 nuts and

lock washers that hold the main transformer to the
machine base. Also remove the 4 in. bolts from
underneath.

17. Using a 5/16 in. nutdriver, remove the 2 screws that

hold the right and left transformer baffle in place (1
screw each). The center assembly and rear

assembly can now be lifted enough to allow the
main transformer and choke assembly to be
removed.

18. With the help of an assistant, lift the front of the

center assembly and slide the main transformer
and choke assembly out through the front of the
machine. Use care -- the assembly is very heavy.

REPLACEMENT PROCEDURE

For lead reassembly steps, also see the Wiring
Diagram.

1. With the help of an assistant, carefully slide the new

transformer/choke assembly into place. Attach it to
the machine base with 4 bolts, lock washers, and
nuts.

2. Attach the right and left transformer baffles to the

machine base (1 screw each side).

3. Connect the heavy lead from the top of the choke to

the positive output terminal.

4. Connect heavy lead B2 to the choke.

5. Connect leads H1 and H4 to the back of the line

switch. See disassembly step for details.

6. Connect leads H2, H3, and H5 to the reconnect

panel.

7. Connect thermostat leads 502 and 503A at their in-

line connectors (right side of the machine).

8. Connect leads X5 and X6 to the control rectifier

(spade connectors).

9. Connect leads X1 and X2 to the output rectifier.

Note the order of the fasteners: bolt, flat washer,
heavy lead, terminal, lock washer, nut.

10. Connect fan lead X4 to fan relay terminal 1 and fan

lead X3 at its in line connector at the fan motor.

11. Install the case front assembly. Connect plug J34

and mount the line switch.

12. Install new cable ties as needed.

13. Install the case sides and top.

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