Citizen Systems CBM-710/720 service manual CPU Peripheral Circuits, CPU and ROM/RAM Circuit

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CBM-710/720 Service Manual

2.CPU Peripheral Circuits

1)CPU and ROM/RAM

The CPU M50734SP has a external memory type. Lower 8-bit address is fetched via the A0/D0 bus line by the 8-bit latch LS373. The 128-KB ROM and 64-KB RAM are used for performing the backup operation for power failure by the super capacitor. The ceramic oscillator is used as CPU clock and transmits 7.37 MHz.

Fig. 2-1 CPU and ROM/RAM Circuit

2)Initial Resetting and Power Failure Interrupt Circuit

The IC12 is an IC for generating the power failure interrupt signal and reset signal. When the power supply voltage decreased due to power failure, etc. this IC performs the voltage inspection and stores all data in the CPU buffer into RAM while printing.

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Contents DOT Matrix Printer Contents Chapter Printer Disassebly and Assembly How to the Upper Cover and Rear Cover How to Remove the Printer Mechanism How to Remove the Control BoardHow to Remove the Power Board and AC Power Unit How to Remove the Auto Cutter Unit How to Remove the Operation Panel Board and PE Sensor BoardChapter Circuit Description Block Diagram OutlineCPU Peripheral Circuits CPU and ROM/RAM CircuitPower Failure Interrupt Circuit and Initial Resetting Printer Control Circuit Printer Control CircuitCutter Control Circuit Normal Reverse StopInterface with Operation Panel Operation Panel CircuitPaper End Sensor Circuit Paper End Sensor CircuitParallel Interface Circuit STBParallel Interface Circuit Serial Interface Circuit Serial Interface Circuit Diagram RS422A Interface Circuit RS422A Interface CircuitPower Circuit Power Supply CircuitChapter Auto Cutter Maintenance and Handling Mechanism and Principle of Operation Cam Switch Cutter Gear Repairing Troubleshooting Page Disassembly/Assembly Page Chapter Circuit Diagram Power Supply Circuit Diagram CBM710/720-001-00 Noise Filter Circuit Diagram CBM710/720-002-00 Paper End Sensor Circuit Diagram CBM710/720-004-00 Circuit Diagram Parallel Circuit Diagram RS232C CBM710/720-008-00 Chapter Parts List Parts List Exploded View CBM-710/720Ref. No Parts No Description CBM-710,720 CBM-710 CBM-72037 Block Diagram CBM-710/720 Block Diagram Power Supply Unit CBM-710/720 PC Board Noise Filter Unit CBM-710/720 Parts Position Noise Filter Unit Control Board Assy RS232C CBM-710/720 Parts List Control Board Assy RS232C OSC Parts Position Control Board Unit RS232C Control Board Assy Parallel CBM-710/720 Parts List Control Board Assy Parallel Parts List Control Board Assy Parallel Parts Position Control Board Unit Parallel Control Board Assy RS422A CBM-710/720 Parts List Control Board Assy RS422A OSC Parts Position Control Board Unit RS422A Operation Panel Unit Parts Position Operation Panel Unit Parts Position PE Detector Unit OP Junction Block Auto Cutter AC-2/AC-3 AC-2 AC-3AC-2 AC-3 Winder AW-2 AW-2