TOC

F-29

TROUBLESHOOTING AND REPAIR

F-29

 

WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST (continued)

 

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6.Make the following voltage tests:

a.Turn the machine OFF between each test.

b.Carefully insert the meter probes into the back of each Molex plug pin cavity to perform the test.

c.Turn the machine ON and pull the gun trigger to conduct the voltage test.

FROM

TO

EXPECTED

LEAD

LEAD

VOLTAGE

 

 

 

B

W

3-20 VDC

(4J1)

(2J1)

(varies depend-

 

 

ing on wire feed

 

 

speed)

 

 

 

7.If the voltage to the wire drive motor armature is zero, check the wires between plug J1 and the wire drive motor. Also check the electrical connec- tor J12 for proper connection and con- tact.

8.If all wires and connectors are good and the voltage to the drive motor armature is zero, the control PC board may be faulty, replace the control PC board.

9.If the motor is running at high speed and the armature voltage is high and uncontrollable, proceed with the tachometer test.

TEST FOR SUPPLY VOLTAGE TO TACHOMETER

1.Disconnect the main AC input power to the machine.

2.Locate plug J1 on the control PC board. See Figure F.9.

3.Locate the following leads on Plug J1:

 

PLUG

LEAD

LOCATION

 

 

515B

5J1

206B

1J1

 

 

4.Connect main input power to the machine.

5.Make the following voltage tests:

a.Turn the machine OFF between each test.

b.Carefully insert the meter probes into the back of each Molex plug pin cavity.

FROM

TO

EXPECTED

LEAD

LEAD

VOLTAGE

 

 

 

515B

206B

15 VDC

(5J1)

(1J1)

 

 

 

 

6.If the 15 VDC is present, check the leads to the tachometer circuit.

7.If the leads are okay and 15 VDC is present, the correct voltage is being received from the control PC board, continue with the Supply Voltage to Tachometer Test.

8.If the 15 VDC is not present and the leads are okay, the control PC board may be faulty, replace the control PC board.

POWER MIG 255C

Page 69
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Lincoln Electric SVM170-A service manual Test for Supply Voltage to Tachometer, 515B 206B 15 VDC 5J1 1J1