Figure f.81, Troubleshooting & repair, Warning – Lincoln Electric INVERTEC POWER WAVE 450 SVM112-B User Manual

Page 265

TROUBLESHOOTING & REPAIR

F-205

POWER WAVE 450

PRE-POWERUP SWITCH BOARD TEST PROCEDURE

FOR REPLACEMENT OF SWITCH ASSEMBLY G2402-2 (continued)

SNUBBER SIGNAL TEST
1. Adjust the grid for a “light” load.

2. Turn ON the variable AC supply applied to the

primary circuit. See Figure F.76.

3. Slowly increase the voltage until the filter

capacitor voltage is 25VDC. See Figure
F.77.

4. Adjust the grid load to get 5 amps output from

the Power Wave. DO NOT PULL MORE
THAN 7-8 AMPS OUTPUT FROM THE
POWER WAVE.

5. Set the Oscilloscope for:

5 V/div/
20 uS/div.

6. Attach the oscilloscope to each of the follow-

ing eight test points. Each test point should
look like the oscilloscope picture in Figure
F.82.

ALL METERS AND OSCILLOSCOPES MUST
BE ELECTRICALLY

ISOLATED Isolated

Transformer).

FIGURE F.81 - FET DRIVE SIGNAL

WARNING

POSITIVE PROBE

12E or 12L

402

12F

404

405

406

12H

408

NEGATIVE PROBE

401
9E or 9L
403
9F
12G or 12M
9G or 9M
407
9H

Turn the variable AC primary supply to zero
volts and then turn it OFF. See Figure F.76.

Once the filter capacitor voltage drops to zero,
turn the arc start switch OFF. See Figure F.79.

0 V

20V/Div

20uS/Div