Daikin / McQuay 860-654873B Microprocessor Control Board (MCB1)

The Daikin/McQuay 860-654873B is a microprocessor control board (MCB1) engineered for remote monitoring and centralized command of up to eight MicroTech-equipped rooftop and self-contained air conditioning units. This PC board computer manages duct static pressure control, temperature distribution, and multi-unit coordination across networked HVAC systems while maintaining independent schedule assignment and alarm oversight. ## Technical Specifications • Part Number: 860-654873B (variants: 860-654873B-11, 860-654873B-06) • Manufacturer: Daikin / McQuay • Product Type: Microprocessor Control Board (MCB1) / PC Board Computer / Chiller Control Board • Power Input: 18 Vac center-tapped from transformer T2 • Internal Power Distribution: 12 Vdc to LED Status Board; 5 Vdc to Keypad/Display backlight • Fusing: Two 2 amp fuses in MCB power supply circuit • User Interface: 12-key keypad with 2-line × 16-character alphanumeric display • Communication Ports: Dual ports (A and B) with six terminals each; RS-232C and RS-485 data transmission standards supported; AMP connectors • Network Capacity: Up to 8 MicroTech-equipped units; 2–8 unit groups for common duct static pressure and temperature control • Scheduling: Four independently assignable schedules per unit or unit combination • Network Configuration: Stand-alone operation or integration with MicroTech Network Master Panel (NMP); IBM-compatible PC with MicroTech Monitor software compatible for full-screen monitoring; optional modem support for remote telephone-line access ## Key Features • Coordinates communications between RMC controller and unit controllers • Emulates remote unit keypad/display via special keystroke combination • Two hex switches for RMC network address assignment • Microprocessor status LEDs (red, green, amber) indicate operational state • Provides common control temperature distribution across multiple units • Manages temperature monitoring via space or return air sensors ## Typical Applications Multi-unit HVAC installations requiring centralized monitoring, networked unit control, and coordinated temperature and pressure management across rooftop and self-contained air conditioning systems. ## Compatibility & Integration Works with MicroTech-equipped Daikin and McQuay applied rooftop and self-contained air conditioning units. Integrates with MicroTech Network Master Panel infrastructure and PC-based monitoring via standard RS-232C/RS-485 interfaces.