Input Contactor Test - Lincoln Electric SVM188-A Service Manual

Lincoln electric welder user manual

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F-26

CONTROL TRANSFORMER TEST (continued)

Secondary

Thermostat

Power

Switch

PROCEDURE

1. With the Input Power OFF, remove the case top,

right side panel and the input access door. The

Control Transformer is located on the back of the

Input Box. See Figure F.12.

• The Primary Leads (black)are routed through the

Input Box and two of them (depending on input

voltage) are connected to L1 and L3 of the Input

Contactor. Any unused leads are to be insulated

and taped.

• The Secondary leads (red) are connected to the

Power

Switch

(X1)

Thermostat (X2).

2. Connect the Input Power and make certain that

rated voltage is present at L1 and L3.

NOTE: The DC-600 does not need be to turned ON.

WARNING

ELECTRIC SHOCK can kill.

• Do not touch electrically hot parts.

TROUBLESHOOTING AND REPAIR

FIGURE F.12 - CONTROL TRANSFORMER

Control

Transformer

and

the

Secondary

DC-600

H2, H3 or H4 (see Input Diagram)

3. Measure the voltage from X1 to X2. It should be

approximately 120VAC.

4. If this reading is incorrect check the connections on

the Primary and Secondary lads. If OK, the trans-

former may be defective.

NOTE: Common causes of control transformer failure

are;

• Improper connection of the Primary leads.

• A defective (shorted) Input Contactor coil.

IMPORTANT

Before installing a new transformer perform the