XPANDER SERVICE MANUAL ocr

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5£RVICe MANUAL 4 M w a J u a i n rnmmmri1rar7 æmiminrera rmmmmmn First edition July 1984 By Michel DO IDIC Oberheim part number 950037 QBERHEIM ELECTR0NICS.1NC.___________________________________ 2250 South Barrington Avenue, Los Angeles, California 90064 TABLE OF CONTENTS Introduction............................................................................Page 2 Mechanical assembly......................................................... .. Êage 3 Xpander circuitry overview.................................................. Page 4 Theory of operation Switching power supply.................................................... Page 6 Dual microprocessor interface....................................... Page 8 Step encoder.......................... Page 10 Vacuum fluorescent displays...... ,.................................... Page 12 Gates and CVs i n ........................................... Page 14 VCO temperature compensation.................................... Page 16 High resolution DAC........................................................ Page 18 VCO and VCF frequency tuning...................................... Page 20 Pulse width…