Lincoln Electric SVM194-A Weld circuit ground test, If the resistance is lower than 500k Ohms

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F-52		TROUBLESHOOTING AND REPAIR			F-52
	WELD CIRCUIT GROUND AND SHORT CIRCUIT TEST PROCEDURE
PROCEDURE			(continued)
				9. If the resistance measurement is too low, check
1.		Turn the engine off.
Weld circuit ground test:				the heavy weld current carrying leads and con-
				nections for damaged insulation or dirt buildup
2.		Measure the resistance between either of the		between the negative (Series Coils) and posi-
		two weld output terminals and a clean chassis		tive (Interpole Coils) circuits. If the low resis-
		ground connection.		tance point is between the stator coils, the coils
		The resistance measurement should be very		will require replacement or repair. Check for
				insulation damage between the yellow and
		high 500,000 (500k) Ohms minimum.		white leads connecting to J5.
If the resistance is lower than 500k Ohms:

3. Remove the welding generator brushes, or pull them away from the commutator and isolate them so they cannot come in contact with any- thing except the brush holder they are attached to. Remove the jumper plug or wire feed mod- ule harness from Plug J5. See wiring diagram.

4. Check the resistance between chassis ground and each output terminal, and between chassis ground and the commutator.

If the commutator has low resistance to chassis ground, the armature will need to be replaced.

5. If the resistance measured at the "POSITIVE" weld terminal is low, carefully examine the inter- pole coils, and the heavy leads, and the brush holders connected to the interpole coils. Check for damaged, dirty or missing brush holder insu- lators. Check for a damaged or dirty weld out- put terminal. Check the yellow lead connecting the brush holder to Plug J5.

6. If the resistance measured at the "NEGATIVE" terminal is low, examine the range selector switch, the series coils, and the heavy leads and brush holders connected to them. Check for damaged, dirty or missing brush holder insu- lators. Check for a damaged or dirty weld out- put terminal. Check the white lead connecting the flashing diode to Plug J5.

7. Test for a short circuit condition between the electrode and work circuits.

8. With the brushes still isolated as described above, check the resistance between the two weld terminals. The resistance should be very high, 500,000 (500k) Ohms minimum.

CLASSIC® 300D & 300G