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9.9
POWER UP FAULTS
9.9.1
Mains Power fuses blow/ breaker trips when SW1 is turned on:
1. Faulty Mains Power Cable and/or Plug
a. Perform Power Cord/Plug, Power Switch, and EMI Board Test (see 9.13.1).
2. Shorted BR1 or BR2 rectifiers.
a. Perform Primary Rectifier Test on both BR1 and BR2 (see 9.13.2.1).
3. Shorted components on Main Power Board.
a. Perform Main Power Board Test (see 9.13.4).
9.9.2
Unit is completely inactive, front panel display is off, no output voltage.
1. Mains Power problem. Open fuse/ tripped breaker
a. Determine if power is available at the mains outlet.
2. Defective MAINS POWER CABLE/PLUG or power switch SW1 or EMI board.
a. Perform Power Cord/Plug, Power Switch, and EMI Board Test (see 9.13.1).
3. Shorted OKC Capacitor Board
a. Visually inspect for damage (see 9.7.12)
4. Defective Main Power Board
a. Perform IPS board test (see 9.13.3).
b. Perform Main Power Board test (see 9.13.4).
5. Defective Control Board:
a. Perform Control Board Test (see 9.13.5).
6. Defective UI board:
a. Perform UI Board Test (see 9.13.6).
7. UI Panel Display is off, but OCV is present on output weld terminals.
a. Connector unplugged from either CN3 on UI board or CN6 on Control Board or
there is an open wire between them.
8. OVER TEMPERATURE symbol displayed on UI screen.
There are four (4) NTC (Negative Temperature Coefficient) thermal sensing devices in the
unit. If the unit is experiencing an overheating issue, the NTCs will prevent damage to the
unit. Two are part of the Main Power Board; one located on the heatsink for the PFC
Transistor, the other on the heatsink for the switching transistors Q3,4,6,7. The Third is
located on the Main Transformer T1. The forth is on the heatsink on the Output
Rectifier board.
TROUBLESHOOTING
9-39
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