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TROUBLESHOOTING & REPAIR

 

F-24

ARC START TRIGGER CIRCUIT TEST (continued)

 

 

CONTROL BOX

SUPORT CASE BACK

 

 

AND CENTER BAFFLE

 

 

CONTROL BOARD LOCATED INSIDE

 

 

WITH WOOD 2 X 4

 

PROTECTION/SNUBBER BOARD

LOCATED ON BACK OF CONTROL BOX

FIGURE F.7 - LOCATION OF PROTECTION/SNUBBER BOARD.

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TEST PROCEDURE

1.Remove main supply power to machine

2.Remove plug J6 from the control board

3.Close the arc start switch or jumper pins “D” and “E” at the six pin amphenol receptacle.

4.Check for continuity between pins 10J6 and 3J6 at plug J6 on the wiring har- ness. Refer to Figure F.8. If 8.4 ohms to 6.0 ohms resistance is indicated then arc start trigger circuit is okay. If a high resistance or open is read then proceed to Step 5.

Note: If arc start switch is opened or jumper removed from pins “D” and “E” the measured resistance in Step 4 should be infinite.

5Test the resistance between 10J6 plug and 10J12 on the projection/snubber board. Also check resistance from 3J6 plug to 3J12 on the projection/ snubber board.

A.If zero ohms resistance is indicated, test is okay. Go to Step 6.

B.If a resistance of any value is shown, check wires and connec-

tions.

10J6

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3J6

PLUG J6 REMOVED

J2

J3

 

 

 

 

J1

J4

J5

J6

J7

J8

G2150

 

 

 

 

 

SQUARE WAVE 255 CONTROL

 

 

 

 

FIGURE F.8 - CONTROL BOARD TEST POINTS.

SQUARE WAVE TIG 255

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Lincoln Electric SVM100-A service manual ARC Start Trigger Circuit Test