Lincoln Electric SVM112-B service manual Preventive Maintenance

D-5 D-5

MAINTENANCE

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PREVENTIVE MAINTENANCE

Perform the following preventive maintenance proce- dures at least once every six months. It is good prac- tice to keep a preventive maintenance record; a record tag attached to the machine works best.

1.Remove the hex head screws from the sides and top of the machine. Remove the handle bar and the machine wrap-around cover. Remove the two case sides. There are hex head screws on each side.

2.Perform the input filter capacitor discharge proce- dure described at the beginning of the Maintenance Section.

3.Disconnect the shunt from the negative (-) output terminal. Failure to do this could cause damage to the shunt circuitry.

4.Clean the inside of the machine with a low pres- sure airstream. Be sure to clean the following components thoroughly (Refer to Figure D.4):

•Display, Snubber, and Shunt printed circuit boards

•Power Switch

•Main Transformer

•Auxiliary Transformers

•Input Rectifier

•Heat Sink Fins

•Input Filter Capacitors

•Output Terminals

•Terminal Strip

8.Reconnect the shunt and wire #467 to the nega- tive (-) output terminal. Make sure the connection is tight.

9.Replace and secure the machine covers and han- dle bar.

10.Remove the overlay from the front panel of the machine. Clean the plastic case with a low pres- sure airstream. Wipe the sensors (Fig D.4 Item 8) with a clean, soft cloth. Make sure the sensors are not scratched in the process.

11.Check the back of the overlays. If the bar code (black square(s)) on the back of the overlay is scratched, apply a dull black spray finish to the scratched-off areas only. If a large area of the bar code is scratched off, the machine either will not recognize the overlay or will mistake the overlay for another one.

12.Inspect gun and cables for good condition.

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5.Examine the capacitors for leakage or oozing. Replace if needed.

6.Examine the wrap-around and side covers for dents and breakage. Repair them as needed. The covers must be kept in good condition to assure that high voltage parts are protected and that cor- rect spacings are maintained.

7.Remove welding cables and check the electrical ground continuity. Use an ohmmeter to measure the resistance between each output terminal and an unpainted surface of the machine case. The meter reading should be 500,000 ohms or more. If the meter reading is less than 500,000 ohms, check for electrical components that are not prop- erly insulated from the case. Correct component insulation, if needed.

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