Hypertherm HD4070 Rev.1 - Manual (Page 192)

HyPerformance HD4070 Instruction Manual 5-29
MAINTENANCE
J 1
D1 D2
D5
TP1 TP5 TP3 TP2 TP4
Start-circuit assembly board PCB2
Operation
The start circuit is a high-speed switch that quickly transfers the pilot arc current from the pilot arc load to the work
load. The start circuit performs 2 functions:
1. It allows the initial pilot arc current to flow through the pilot arc lead quickly, with little impedance.
2. After initial pilot arc current is established, the start circuit introduces impedance to the pilot arc load to aid in
transferring the arc to the workpiece. See schematic on following page.
Pilot arc control PC board LED list
LED Signal description/ Function
D1 Pilot Arc Active
D2 +15 Volts power indicator
Process Pilot arc current
Marking 10 amps
30/45-amp process 20 amps
80-amp process
20 amps – Mild steel
25 amps – Stainless steel
130-amp process
30 amps – Mild steel
35 amps – Stainless steel and Aluminum
200-amp process 40 amps
Pilot arc current levels
The pilot arc current level will change depending on the chosen process and arc current level. See table below.
D1
IGBT output D2
+15 VDC