Lincoln Electric SVM162-B service manual 54TROUBLESHOOTING & REPAIRF-54, See Figure F.14

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F-54TROUBLESHOOTING & REPAIRF-54

SCR BRIDGE ASSEMBLY REMOVAL AND REPLACEMENT (continued)

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REMOVAL PROCEDURE
1.	Remove input power to the TIG 275
2.	machine.
	Using the 3/8” nut driver, remove the case
3.	sides and top.
	Label and cut leads G1 and G2. See
4.	Figure F.14.
	Label and cut leads G3 and G4. See
5.	Figure F.14.
	Remove the 1/2 “ nut securing leads B and
6.	217. See Figure F.14.
	Using a 7/16” nut driver, disconnect Pos.
7.	lead and lead 218.S Figure F.14.
	Using a 1/2” nut driver, disconnect Pos.
8.	lead and lead 218. See Figure F.14.
	Using a 1/2” nut driver, remove lead 216
	and aluminum lead X1 connecting to the
	main transformer. See Figure F.14. Note
9.	washer placement upon removal.
	Using a 1/2” nut driver, disconnect lead
	220A and shunt from the output bridge. See

Figure F.14.

10. Using a 3/8” nut driver, remove the four SCR bridge mounting bolts. Note insulator washer placement upon removal.

REPLACEMENT PROCEDURE 1. Replace the SCR bridge.

2. Replace the four SCR bridge mounting bolts previously removed.

Note: Be sure to replace insulating wash- ers in their proper positions.

3. Reconnect lead 218 and Pos. lead previ- ously removed.

4. Replace the shunt and lead 220A previous- ly removed.

5. Replace the 1/2” bolt securing lead 216 and the aluminum lead X1 originating from the main transformer.

6. Reconnect the negative lead to the free wheeling diode.

7. Replace the 1/2” bolt securing leads B and

217 previously removed.

8. Reconnect leads G1, G2, G3, and G4. Splice, solder and insulate as necessary.

9. Replace case sides and top.

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PRECISION TIG 275