Lincoln Electric INVERTEC V275-S Service Manual page 49

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MAIN SWITCH BOARD TEST (CONTINUED)
309
313
307
Input Signal Test
10. Locate leads 308 and 309 on plug J10.
See Wiring Diagram. See Figure F.4.
11. Carefully apply the correct input power to
the V275-S.
12. Make sure that the Mode Switch is in the
Stick position.
13. Using a fluke frequency meter carefully
check for 30KHZ from leads 308 and 309.
NOTE: This is the IGBT gate drive signal from
the control board to the switch board.
14. Locate leads 310(-) and 307(+) on plug
J10. See Wiring Diagram. See Figure F.4.
15. Using a multimeter carefully check for
10.5VDC to 13.5VDC. This is the voltage
applied to the precharge relay and should
be present approximately three seconds
after power is applied to the machine.
TROUBLESHOOTING & REPAIR
Figure F.4 - Plug J10
V275-S
311
308
310
Fault Signal Test
16. Locate leads 311(+) and 313(-) on plug
J10. See Wiring Diagram. See Figure F.4.
17. Carefully measure the DC voltage at leads
311(+) and 313(-). Normal expected volt-
age is less than 1.5VDC. This voltage
should always be less than 1.5VDC
unless there is a capacitor fault condition.
18. Below are the conditions that could cause
this voltage to be greater than 1.5VDC.
• Input capacitors over voltage. Greater than
455VDC.
• Input capacitors under voltage. Less than
235VDC.
• The input capacitors may need condition-
ing. See Filter Capacitor Conditioning.
• One of the input capacitors may be faulty.
• The switch board may be faulty.
• If the reconnect switch is configured for a
voltage less than 380VAC and the applied
voltage is greater than 380VAC, a fault con-
dition will occur. The actual capacitor volt-
age will oscillate between approximately
70VDC and 135VDC.
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