Specifications

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SECTION 5 MACHINE TESTING / TROUBLESHOOTING / SERVICE
5.8.4 Pulse Width Modulator
IC6 is the Pulse Width Modulator IC and it generates the drive signals, which drive the IGBT circuitry. This
chip also provides the +5-volts for the board.
Current control comes into the board on Plug 6 pin 14 (P6-14) and is routed through IC5 on pin 6, out
through pin 7, through the 50-amp jumper J2, then input to IC6 on pin 2. The IC has two adjustments,
R34, the frequency adjustment and R51, the dead band adjustment. The frequency adjustment is set to
16 KHz. at the factory. The output of IC6 is routed to IC7 and IC8 from pins IC6-11 and IC6-14 respectively.
These signals are then routed to the IGBT drive transformer T1 and to the SCR drive transformer T2.
CONTENTS