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Wang 600 Fault Summary
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S/N CC 2001 - List of Faults Found & Fixed
1 Main Power Supply
- Mains wiring upgraded for safety Done
- Shorted rectified diode replaced Done
- Main filter capacitors replaced Done
- Filter capacitor original design error corrected Done
2 -12v Regulator
- Driver transistor replaced Done
- 723 regulator IC replaced Done
3 Volt Clamps on High-Risk Rails
- Clamp fitted to +5v to protect 200+ TTL ICs Done
- Clamp fitted to -11.5v to protect vintage Mostek MK4008 RAM ICs Done
4 +12v Regulator
- Ampacity improved by installation of 7812 regulator Done
5 Wire ROM Power
- Shorted tantalum in wire driver supply replaced Done
6 Corroded IC Sockets
- Two ICs on the 5964 ALU board had extensive corrosion in and under their sockets
- Sockets removed, board and ICs cleaned, ICs directly soldered Done
7 Wire ROM Data
- One silent column, KK field bit 1, sense circuit fault Repaired, faulty sense latch IC replaced
- Four silent rows, possible select diode or broken wire Not Repairable, Worked-around with ROM Emulator
8 ROM Emulator
- Wire ROM will be replaced with ROM emulator Done
- Original ROM image downloaded, repaired and uploaded to emulator Done
9 Faulty 9946 IC in MAVx gating
- 9946 quad-NAND with stuck outputs prevents RAM addressing
- Successfully replaced with 74H01 IC Done
10 Faulty 9946 IC on 6187 Keyboard PCB
- 9946 quad-NAND prevented keyboard RECORD PROG and STEP keys from working
- Successfully replaced with 74H01 IC Done
11 Faulty ICs x3 and Dry Joints on 6184 PCB
- 2x faulty 9946 quad-NANDS stopped keyboard enable
- Dry joints caused intermittent operation of the keyboard enable circuit
- Faulty 7404 hex inverter prevented keycode data from latching into the logic engine
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