MAINTENANCE
3-26
Service Manual
POWER BOARD
The power board contains part of a "soft start' or "in-rush" circuit, an over-voltage shut down circuit,
and the high-voltage power circuits for left and right inverters. Voltages can be taken at the rear of
the power PCB to check these functions.
WARNING
SHOCK HAZARD: The "E" terminals and J1 are accessible from the back
side of the power PCB. Use extreme caution when taking these readings.
Voltages up to 300 VDC are present at the rear of the power PCB.
The large electrolytic capacitors, (blue-cased cylinders) located on the
front side of the power PC board store large amounts of energy in the
form of electrical voltage. Even if the power is off, dangerous voltages
exist at the capacitor terminals on the PC board and on certain areas of
the PC board. Never discharge the capacitors with a screwdriver or other
implement... explosion, property damage and/or personal injury will
result.
Wait at least 5 minutes after turning the power supply off before handling
the PC board or capacitors. If questions or problems arise during
servicing, call Hypertherm Technical Services at 1-800-643-9878.
Use extreme caution when taking the voltage readings on the back of the power PCB - see warning
above. Use an isolated or "floating" digital volt meter, since high voltages are present. The following
table lists the test points, their descriptions and values. Refer also to Figure 3-5 to locate test points.
Test Point Description Value
E1 to E3 High-voltage power - Left Inverter +300VDC
E14 to E3 One-half of High-voltage power - Left Inverter +150VDC
E4 to E5 High-voltage power - Right Inverter +300VDC
E15 to E5 One-half of High-voltage power - Right Inverter +150VDC
J1-5 to J1-4 "Soft start" signal from control PCB. After incoming voltage is +12VDC 5 sec. after
accepted by control board, control board sends +12VDC to relay throwing power switch
RL1 on power board. LINE VOLTAGE LED will remain lit until "soft S1.
start" signal is complete (about 5 seconds after S1 is thrown).
J1-6 to J1-4 Shut down signal from power board. Protection circuit on power +12 VDC normally.
board will go low (≈ 0 VDC) to control board to shut down power ≈ 0 VDC if voltage too
9-96 supply if it detects over voltage. high.
Power Board Test Points
9-96
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