Lincoln Electric SVM112-B service manual Table F.5 Switch Board 4 Resistance Test Table

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F-71

F-71

TROUBLESHOOTING & REPAIR

FIELD EFFECT TRANSISTOR/SWITCH BOARD TEST (continued)

TABLE F.5 – SWITCH BOARD 4 RESISTANCE TEST TABLE

Apply	Apply
Positive	Negative
Test	Test
Probe to	Probe to	Test		Repair	Next
Terminal	Terminal	Result	Conclusion	Action	Procedure
4B	12D	Greater	OK	None	Continue
		than 1K
		ohm
		Less than		Replace 4	Snubber
		100 ohms	Shorted	Switch	Resistor
				Boards	Test
12D	4B	Less than	OK	None	Continue
		100 ohms
		Greater	Open	Replace 4	Snubber
		than 1K		Switch	Resistor
		ohm		Boards	Test
9D	3B	Greater	OK	None	Continue
		than 1K
		ohm
		Less than	Shorted	Replace 4	Snubber
		100 ohms		Switch	Resistor
				Boards	Test
3B	9D	Less than	OK	None	Continue
		100 ohms
		Greater	Open	Replace 4	Snubber
		than 1K		Switch	Resistor
		ohm		Boards	Test
4B	9D	Less than	OK	None	Continue
		100 ohms
		Greater	Open	Replace 4	Snubber
		than 1K		Switch	Resistor
		ohm		Boards	Test
9D	4B	Greater	OK	None	Continue
		than 1K
		ohm
		Less than	Shorted	Replace 4	Snubber
		100 ohms		Switch	Resistor
				boards	Test

NOTE: K ohm = ohm reading multiplied by 1000.

NOTE: Always make sure that all four Switch Boards are changed at the same time. Never mix an old style (different part number) Switch Board with a new style (new part

number).

POWER WAVE 450