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F-32F-32

TROUBLESHOOTING & REPAIR

CONTROL BOARD TEST (Continued)

J2

 

J5

 

 

J6

 

 

J7

J1

 

 

 

J8

 

 

J4

J3

 

 

Firing Board

 

Control Board

FIGURE F.14. CONTROL BOARD LOCATION

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TEST PROCEDURE FOR NORMAL CON- TROL BOARD OPERATION

1.Remove main supply power to the Multi- Source.

2.Remove screws, loosen and lower the front panel to access and inspect the con- trol board located in the right side of the control box. See Figure F.14.

3.Apply the correct three-phase input power to the Multi-Source. Turn on the machine.

WARNING

WHEN THE MULTI-SOURCE IS

TURNED ON, THE OUTPUT

TERMINALS ARE ELECTRICAL-

LY HOT.

4.The white power light, located on the front control panel, indicates the control board is receiving the DC voltage that is supplied from the rectified secondary voltage of the control transformer. This voltage can range from 38VDC with 345VAC applied to the machines input, to 58VDC with 600VAC applied to the Multi-Source. This voltage can be measured at Plug J2-pin4

(+)lead #274, to plug J2-pin2 (-) lead #273. See Figure F.15. Normal voltage on the white light is 3.5VDC. If 5.0VDC is present the light may be open. This can be measured at plug J1-pin 7(+) lead #230 to plug J1-pin 8(-) lead #341.

5.LED 1 is an indication of the machine’s output voltage. At normal output voltages LED1 should be brightly lit. Normal open circuit voltage (OCV) at the welding output terminals is approximately 80VDC. This voltage can be checked at Plug J1-pin 1(+)

lead #201 to Plug J1-pin 9(-) lead #222A. If the voltage is correct but LED1 is not lit, the control may be faulty. See Figure

F.15.

6.LED 2 indicates the level of the control sig- nal that is passed to the firing board. The brightness of LED 2 is inversely propor- tional to the output of the machine. As the control signal decreases (LED 2 gets dim- mer) the machine’s output increases. The control signal can be measured at Plug J1- pin 4(+) lead #231 to Plug J1-pin1(-) lead #201. Normal range is about 12VDC at open circuit to about 3VDC when high or maximum output is required. See Figure

F.15.

7.LED 3 indicates that the machine’s output is greater than 10 amps and the control board is developing a signal for the cool- ing fan to operate. This signal activates a fan motor driver circuit that is incorporated within the control board. See step 10 (LED 6).

8.LED 4 is an indication that either a ther- mostat, output current or output over-cur- rent is calling for the fan motor to operate.

See Figure F.15.

9.LED 5 lights when the current feedback signal from the output shunt is too high. If LED 5 is lit for 5-8 seconds, the enable signal from the control board to the firing board is sent high (over 12VDC) (LED2). If the output current overload is of a short time duration LED 5 may only be lit briefly. In either case the machine’s output will be zero and the output will remain off for about 75 seconds. See Figure F.15.

MULTI-SOURCE

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Lincoln Electric SVM155-A service manual Control Board Test, See Figure F.15

SVM155-A specifications

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