Advanced Troubleshooting Guide Pre-Tests - Thermal Dynamics CUTMASTER 60i Service Manual

CUTMASTER 60i
5.06

Advanced Troubleshooting Guide Pre-Tests

Circuit description.
The Cutmaster 60i includes single phase models and 3 phase models. They cannot be switched from one to the
other. There are also specific models to meet CE requirements.
AC
Input Rectifier and Bias Supply
The basic system includes an input rectifier, a Bias Supply board, a Power Factor Correction and Boost board, an
Inverter board and a Control & Display board. The A Series units include an Automation Interface board and the
CE (European) units have an EMI/RFI filter before the input rectifier.
Both single and 3 phase power enter through a 3 phase circuit breaker on the rear panel that also acts as ON/OFF
switch. Exiting the breaker AC power goes through the input rectifier, D300, which includes an internal SCR at its
positive output. CE units place the EMI filter between the circuit breaker and the input rectifier. The Bias Supply
board also mounts on D300. Initially the rectified DC power passes through inrush resistors R300-303 on the Bias
Supply board to limit the current while charging the bulk capacitors. After about 4 seconds to allow capacitor charg-
ing the SCR in the D33 module is turned on, bypassing the inrush resistors.
Power Factor Control (PFC)
The rectified DC voltage from D300 varies with the incoming line voltage but the Power Factor Control (PFC) &
Boost circuit accepts the rectified DC from any AC line voltage, 208VAC to 480VAC, and boosts it to the same regu-
lated 750 VDC at the bulk capacitors. Variations in the AC line voltage have no effect on the output of the Plasma
power supply.
Inverter board
The Inverter board takes the 750 VDC and converts it to a high frequency square wave for the transformer primary.
Signals from the Control & Display board control the pulse width of the square wave to control the output current.
At the transformer secondary the high frequency is rectified back to DC by the output diodes and filtered by the
output inductor to provide clean DC current for the plasma torch. The Inverter board also accepts inputs such as
the torch trigger (START), Parts in Place (PIP), output current signal from the Hall Effect transducer HCT1 and gas
pressure passing them to the Control & Display board and accepting control signals for OK to Move, the propor-
tional gas control solenoid and the fan. Also controlled is a transistor (IGBT) switch to turn the pilot on and off at
the correct times.
Control & Display board
The control & Display board holds the microprocessor with the program that operates the system. Along with the
Display it allows setting the output current, selecting different modes of operation, configuring the system for dif-
ferent torches and lead lengths. Also displays status information including any faults that may occur.
5-8
SIMPLIFIED DIAGRAM
SCR
PFC &
BOOST
D300
BIAS
SERVICE
* *
* *
INVERTER
CONTROL & DISPLAY Art # A-13333
(+)
Tip
(+)
W ork
Manual 0-5475