A controller for a hot melt adhesive dispensing system has a main circuit board and power modules which are removably received on a controller enclosure. The power modules are directly couplable with the main board and with cord sets from heated hoses of the dispensing system, eliminating the need for wiring harnesses to be routed between these components. Accordingly, the main board and power modules may be readily removed and replaced in the field to permit efficient servicing and modification of the system to accommodate the needs of various applications.