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F-16

TROUBLESHOOTING AND REPAIR

F-16

TACH FEEDBACK TEST (continued)

FIGURE F.2 – PLUG J84 LOCATION

BLUE RED

Black

J84

PROCEDURE

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1.Remove input power from the wire feeder unit.

2.Using the 3/8 in. nut driver, remove the cover from behind wire reel.

3.Locate plug J84 on the feed head board. Refer to Figure F.2. Do Not remove the plug from the feed head board.

4.Apply the correct input power (from the POWER FEED® 25M control cable) to the wire feeder unit and check for approximately 5VDC from (red wire) positive to (black wire) negative. This is the supply voltage from feedhead board to the tach feedback unit. If the 5VDC is missing or not correct, the feedhead board may be faulty. Also check for loose or faulty wires and connec- tions.

5.With the gun trigger activated and the motor running, check the feedback voltage at plug J84 (blue wire) positive to (black wire) negative. Normal feedback voltage is approximately 2 VDC. If the correct supply voltage is present and the feedback voltage is missing, the tach unit may be faulty. With the motor NOT running, the feedback voltage may be either 0 or 5 VDC depending upon where the motor stopped.

6.Remove input power from the wire feeder unit.

7.Install the wire feeder cover with the 3/8 in. nut driver.

POWER FEED® 25M

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Lincoln Electric SVM185-A service manual Blue RED