Troubleshooting & repair, Capacitor balance test (continued), Warning – Lincoln Electric INVERTEC SVM129-B User Manual
Page 68
TROUBLESHOOTING & REPAIR
F-30
F-30
INVERTEC® STT® & STT® II
CAPACITOR BALANCE TEST (continued)
FIGURE F.10 – SWITCH BOARD TEST POINTS
L8441
L8441
SWITCH
SWITCH
9
9
12
12
TEST PROCEDURE
1. Turn off the INVERTEC® STT® & STT® II
and disconnect main AC input power to the
machine.
2. Using the 5/16" nut driver, remove the
case wraparound cover.
ELECTRIC SHOCK can
kill.
• With input power ON,
there are high voltages
inside the machine. Do
not reach into the
machine or touch any
internal part.
3. Carefully apply the correct input power to
the machine.
NOTE: This test should only be conducted
when the machine reconnect switch
and jumper are set for high voltage
(above 380VAC) and the proper line
voltage is applied.
4. Test for VDC across terminals #9 and #12 of
one switch board and repeat the test for the
other switch board. See Table F.4 in this
procedure for expected voltage readings.
See Figure F.10.
A. If less than 25VDC difference is mea-
sured between each switch board, the
capacitive balance is OK. This indi-
cates that capacitors C1, C2, and resis-
tors R1 and R9 are functioning proper-
ly. Proceed to Step #5.
B. If more than 25VDC difference is mea-
sured between each switch board, test
each of the following components:
Capacitors C1, C2 and resistors R1
and R9. See the INVERTEC® STT® &
STT® II Wiring Diagram.
WARNING