Hypertherm HD4070 Rev.8 User Manual
Page 187
MAINTENANCE
5-40
HD4070
Instruction Manual
3
Phase Loss Detection Board PCB1 Status Indicators and Operation
Operation
The phase-loss detection circuit checks the incoming voltage and verifies that the voltages between the 3-wire
inputs are within +/- 15% of each other.
• After contactor CON1 closes, opto-coupler U
1
on PCB1 is activated, shorting pins 1&2 of PL1 together and
illuminating LED1.
• If LED1 does not illuminate:
• Verify that voltages across points A B and C, phase-to-phase are approximately 255 VAC. If voltages are
not within +/- 15%, LED1 will not illuminate. Check the incoming line voltage and the contacts on CON1.
• Check PCB1 fuses F1-F3. If any of the fuses are open, then PCB1 is faulty.
• Check jumper on P2 and verify that the jumper is set for 211V.
Phase-loss board PCB1 location on chopper CH2
See page 6-3 for location of CH2.
LED1
U1
A
B
C
F1
F2
F3
P2
P2 Jumper
for 211V