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F-26

TROUBLESHOOTING & REPAIR

F-26

 

 

TYPICAL SCR GATE VOLTAGE WAVEFORM

SCOPE SETTINGS

This is a typical SCR gate pulse voltage

 

 

waveform. The machine was in an open cir-

Volts/Div

. .2 V/Div.

cuit condition (no load) and operating prop-

 

 

erly. Note that each vertical division repre-

Horizontal Sweep

.5 ms/Div.

sents 2 volts and each horizontal division

 

 

represents 5 milliseconds in time.

Coupling

. . . . .DC.

Note: Scope probes connected at Plug J3

Trigger

. .Internal.

on the control board. The (+) probe to lead

 

 

G2, and the (-) probe to lead 204.

 

 

 

 

 

WIRE-MATIC 250

Page 79
Image 79
Lincoln Electric SVM 117-A service manual Typical SCR Gate Voltage Waveform