Heating device for detecting state of adjustment portion that adjusts period of connection with alternating current source

An image forming device comprising:

• a heating device comprising:
• a heater having a first terminal and a second terminal, the first terminal being configured to be connectable to one terminal of an alternating current source;
• an adjustment portion configured to selectively establish and disconnect a first connection between the second terminal and another terminal of the alternating current source;
• a switching portion configured to selectively establish and disconnect a second connection between the heater and the alternating current source;
• and
• a generating circuit having a third terminal and a fourth terminal, the third terminal being connected to the one terminal of the alternating current source, the fourth terminal being connected between the second terminal and the adjustment portion, the generating circuit being configured to generate a zero-cross signal indicating a zero-cross timing concerning output of the alternating current source;
• an image forming unit configured to form an image on a recording sheet in response to image data;
• and
• a processor configured to:
• adjust a connection period during which the adjustment portion establishes the first connection;
• detect a state of the adjustment portion in response to the zero-cross signal;
• and
• perform an error process when the detected state of the adjustment portion indicates that the adjustment portion cannot disconnect the first connection.