Maintenance

OPERATING INSTRUCTIONS

3.Remove the blue jumper lead connected between #1 on the coil of the main relay and #7 on the coil of the transfer relay. (The main relay is the upper right relay when facing the left end of the control box. The transfer relay is just to the left of the main relay.)

4.Replace the LAF-3 control cover.

5.Set the “POS — NEG” switch (on both the NL Option and the DC-1500) to correspond to the polarity of the electrode cable connection.

6.Set the mode switch on the front of the DC-1500 to “Variable Voltage”.

7.Set the toggle switch on the front of the DC-1500 to “Output Control Remote”.

8.Set the DC-1500 welding current as required by the procedures using the K775 Remote Output Control shipped with the NL Option.

9.Set the LAF-3 “Inch Speed” control near minimum so the electrode touches the work lightly before starting the arc. The NL Option “Inch Speed” control is not in the circuit.

10.Set the “Hot Start Control” on the NL Option at #2. This setting does not change the open circuit voltage, but it will improve starting, particularly at low currents. Adjust the control for optimum starting.

NOTE: The “Hot Start Control” does not affect the starting method of the LAF-3, i.e., “cold” start, “hot” start, etc. See IM-198-B, Sec. 2.4.9.

11.Set the NL Option “Contactor Drop-Out Delay” switch to “On”. This circuit delays opening of the output con- tactor for a fixed length of time after wire feeding stops to prevent sticking.

Operation When Connected to the LT-3 or LT-34

Follow the same instructions as above except in Step 1, connect per M13322. Omit Steps 2, 3 and 4. Set the “Inch Speed” control on the NL Option as low as possible so the electrode touches the work piece lightly before starting the arc.

Overload Protection

The NL Option kit includes two fuses on the front panel. The upper fuse (2 amp slow blow) protects the inching cir- cuit when the option is used with LT-3 and LT-34 wire feed- ers. The lower fuse (2.8 amp slow blow) protects the 115 volt DC circuit (#1 and #2). If replacing either fuse use the same size and type.

WARNING

OVERLOAD PROTECTION

The DC-1500 has built-in protective thermostats. If the rec-

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.

tifier or transformer reaches the maximum safe operating temperature because of frequent overload or high room tem- perature plus overload, the contactor drops out stopping the welder. The thermostat automatically reset when the tem- perature reaches a safe operating level. Press the “On” but- ton to start the welder.

The power rectifiers are also protected by a special solid state circuit. With the occurrence of a short circuit or ex- cessively high overloads, the input contactor opens. When the overload is removed, press the “On” button to start the

GENERAL MAINTENANCE

1.The fan motors have sealed bearings which require no service.

2.In extremely dusty locations, dirt may clog the air chan- nels causing the welder to run hot. Blow out the welder with low pressure air at regular intervals. Also blow dirt out of the NL Option box.

welder.

An 8 amp slow blow fuse located on the front of the machine protects the 115 volt auxiliary AC circuit (#31 and #32) from overload. If replacing, use the same type and size fuse.

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