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F-14

F-14

TROUBLESHOOTING & REPAIR

INPUT FILTER CAPACITOR DISCHARGE PROCEDURE (continued)

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WARNING

ELECTRIC SHOCK can kill.

• Have an electrician install and service this equipment.

Turn the input power off at the fuse box before working on equipment.

Do not touch electrically hot parts.

Prior to performing preventative maintenance, perform the following capacitor discharge procedure to avoid electric shock.

DISCHARGE PROCEDURE

1.Remove the input power to the POWER WAVE 355/405.

2.Using the 5/16” wrench remove the screws from the case wraparound cover.

4.Obtain a high resistance and high wattage resistor (25-1000 ohms and 25 watts minimum). This resistor is not with the machine. NEVER USE A SHORTING STRAP FOR THIS PROCEDURE.

5.Locate the eight capacitor terminals shown in fig- ure F.1.

6.Using electrically insulated gloves and pliers, hold the body of the resistor with the pliers and con- nect the resistor leads across the two capacitor terminals. Hold the resistor in place for 10 sec- onds. DO NOT TOUCH CAPACITOR TERMINALS WITH YOUR BARE HANDS.

7.Repeat the discharge procedure for the other three capacitors.

8.Check the voltage across the terminals of all capacitors with a DC voltmeter. Polarity of the capacitor terminals is marked on the PC board above the terminals. Voltage should be zero. If any voltage remains, repeat this capacitor dis-

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3. Be careful not to make contact with the capacitor

charge procedure.

terminals located at the top and bottom of the

 

switch board.

 

FIGURE F.1 – LOCATION OF INPUT FILTER CAPACITOR TERMINALS

EIGHT

CAPACITOR

TERMINALS

- +

- +

INSULATED

PLIERS

-+ - +

POWER

INSULATED

GLOVES

RESISTOR

 

POWER WAVE 355/405

 

Page 56
Image 56
Lincoln Electric SVM159-A service manual Input Filter Capacitor Discharge Procedure