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F-21

F-21

TROUBLESHOOTING & REPAIR

MAIN TRANSFORMER (T1) VOLTAGE TEST (continued)

FIGURE F.8 – MAIN SECONDARY LEAD TEST POINTS

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8.Read the meter.

a.If proper voltage is present for all three phases, proper main input supply volt- age is being supplied.

b.If proper voltage is not present in any or all of the three phases, check input fuses and leads.

9.Test with an AC voltmeter for proper main input supply voltage from the output side of the input contactor (CR1). See the Wiring Diagram and Figure F.7.

a.T1 to T2.

b.T2 to T3.

c.T1 to T3.

10.Read the meter.

11.Test with an AC voltmeter for approximate- ly 50VAC across each of the three main secondary start leads located at the SCR/Diode Rectifier Bridge. Remove the red insulating paint to achieve good con- tact if necessary. The transformer voltages will vary with the input line voltages. See Figure F.8. See the Wiring Diagram.

a.If one or more of the above voltage tests are incorrect, check for loose or faulty connections.

b.If the connections are good, then the main transformer may be faulty. Re- place the main transformer.

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a.If the proper voltage is present for all three phases, the input contactor is working properly.

b.If the proper voltage is not present for any or all of the three phases, the input contactor may be faulty. See appropri- ate Input Contactor Test.

IDEALARC R3R

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Lincoln Electric R3R-500, R3R-300 service manual Figure F.8 Main Secondary Lead Test Points