SECTION 9 − TROUBLESHOOTING
9-1. Removing Cover and Measuring Input Capacitor Voltage
Tools Needed:
5/16 in
!900 Volts dc can be present on the capacitor bus and significant DC voltage can remain on capacitors after unit is Off. Always check the voltage on both inverter assemblies as shown to be sure the input capacitors have discharged before working on unit.
Turn Off welding power source, and disconnect input power.
Remove cover
1Power Interconnect Board PC2
2Voltmeter
Measure the dc voltage across the + bus terminal and − bus terminal on PC2 as shown until voltage drops to near 0 (zero) volts. Measure input capacitor voltage on both inverter assemblies before proceeding.
3 Typical Bleeder Resistor
An example of a typical bleeder resistor is shown on this page.
Proceed with job inside unit.
Reinstall cover when finished.
1
2
+ lead to left bus terminal, − lead to right bus terminal
1
2
3
Typical Bleeder Resistor
25 to 1000 ohm, 5
watt resistor
+ lead to left bus terminal, − lead to right bus terminal
#16 AWG 1000 volts dc insulation rating, approx 3 in (76 mm) leads
802 985 / Ref. 803
