Lincoln Electric SP-250 service manual Leads

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F-23 TROUBLESHOOTING & REPAIR F-23

ACTIVE SCR RECTIFIER ASSEMBLY TEST

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TEST PROCEDURE

1.Disconnect main AC input power to the machine.

2.Disconnect Molex Plugs J3 and J6 from the G2252 Control Board or remove Plug J3 from G1992 Control Board (Code 9402 only)

See Figures F.5A and F.5B.

SP-250 CONTROL

G2252

J2

J8

J7

J4

J9 J3

J5 J6

3.Test with an Analog Volt-Ohm meter that capacitors have completely dis- charged.

4.Disconnect leads X2 and X3 from the negative capacitor bank using a fi" open end wrench.

See Figure F. 6.

LEADS

X2 AND X3

NEGATIVE

CAPACITOR

BANK

BUSS BAR

FIGURE F.6 - Location of Leads X2 and X3.

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FIGURE F.5A - Control Board Molex Plug Locations for G2252 PC Control Board.

SP-250 CONTROL

G1992

J2

J8

J7

J4

J9

J5

J3J6

FIGURE F.5B - Control Board Molex Plug Locations for G1992 PC Control Board (Code 9402 only.)

5.Separate leads X2 and X3 from the negative capacitor bank buss bar. Be sure there is no electrical con- tact. See Figure F6.

NOTE: DO NOT DISASSEMBLE THE SCR RECTIFIER HEAT SINK ASSEM- BLY.

6.Construct the circuit shown in Figure F.8. One 6-volt lantern battery can be used. R1 and R2 resistor values are ±10%. Set voltmeter scale low, at approximately 0-5 volts or 5-10 volts.

a.Test the voltage level of the bat- tery. Short leads (A) and (C). Close switch SW-1. Battery voltage should be 4.5 volts or higher. If lower, replace the bat- tery.

IDEALARC SP-250