Cincinnati Milacron 3 545 1000A Control Board
The Cincinnati Milacron 3 545 1000A (also written as 3-545-1000A) is a printed circuit board used in older Milacron CNC machine tools, including the Sabre, Arrow, and Maxim series machining centers. The board is believed to be part of the axis drive interface or PLC I/O section of the Acramatic 900 or 2100 control systems. This component is critical for machine operation in legacy equipment.
Hardware Architecture
The board is a double-sided FR4 PCB measuring approximately 260 mm x 170 mm. It contains several key ICs: a Motorola 68B09EP microcontroller (8-bit, 2 MHz), multiple optocouplers (HP 6N137) for signal isolation, and a bank of power transistors (TIP147, TIP142) for output drivers. The board also includes 16 general-purpose digital inputs (24 V DC) and 8 relay outputs (30 V DC / 1 A). Power regulation is provided by a 7805 linear regulator (+5 V) and an LM317 for adjustable voltage.
Connectors and Interfaces
Three 50-pin IDC ribbon connectors (CN1, CN2, CN3) link the card to the main backplane of the CNC rack. A 4-pin Molex connector supplies 24 V and 5 V DC from the power supply. Onboard jumpers (JP1-JP4) set the board address (I/O range). A 5-pin header (J4) provides a serial RS-232 service port for diagnostics. Status LEDs (green, red) show +5 V power and CPU heartbeat.
Environmental and Replacement
Operating temperature: 0°C to 55°C. Storage: -20°C to 70°C. All capacitors are through-hole electrolytic (rated 85°C). The board is not conformal coated; thus moisture and dust can cause failure. Replacement requires matching firmware revision (sticker on the 68B09EP). Spare boards should be stored in anti-static bags. No field repair is recommended beyond capacitor replacement.
Known Applications
Used in Cincinnati Milacron Sabre 750, Sabre 1000, Arrow 500, and Arrow 1000 machining centers. The board interfaces the Acramatic CNC with the machine’s tool changer, coolant pump, axis limit switches, and spindle drive. Failure symptoms include intermittent tool changer operation, alarm 39-15 (I/O bus fault), or missing inputs on the diagnostic screen.
Maintenance Notes
Recalibration of the analog input section (if present) requires a precision voltage source and the service manual. Board removal: disconnect power, label all cables, and pry gently with a flathead screwdriver from the card guides. After replacement, a machine parameter restore may be needed. The 3 545 1000A is a rare part; cross-reference with Milacron part number 3-545-1000A Rev. C.
