Pcb1_Pwm Circuit (0558038317) - ESAB Powercut 1600 Service Manual

SECTION 4 DESCRIPTION Of OPERATION

4.8.7 PCb1_PwM Circuit (0558038317)

PWM / IGBT Gating signal
This section controls the frequency and width of the gating signal supplied to the IGBTs.
The circuit receives the current reference signal from the current reference and error amplifier.
This circuit is triggered on from the microcontroller. In the event that there is an over current condition the
PWM chip can be shut down from either the microcontroller or from the Protection circuit (see Protection
Circuit section XX)
The PWM circuit receives an enable signal from the microcontroller chip to begin the output of pulses that
are then sent to the Power Board via the ribbon cable.
The PWM chip receives the current reference signal on pin 1, the ERR pin, which it receives from the error
amplifier.
Adjustment
Adjust R29 to read 38 KHz at TP1
Adjust R43 to read 1.45 VDC at TP3
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