HEATER AND PHYSICALLY REQUIRED VALUE SETTING CIRCUIT

摘要

A heater unit and control circuitry therefor, the heater unit typically being employed as a preheater or primary heater for the installation and removal of electronic components from a PCB or the like and having various means for accommodating (a) an uneven surface or the presence of other components on the underside of the board or (b) an unlevel board. Moreover, a heater unit for sequentially providing preheat and primary heat from different zones of the heater is disclosed. A probe for use with the heater for sensing the temperature at various points on the board is also disclosed. The circuitry is characterized by ease of calibration of the heater temperature, the temperature transducing circuits, and the temperature setting circuits thereof. Moreover, circuitry is provided to insure the same voltage out of each input source in response to the input source measuring or setting a common temperature.