Diagnosis of source of error using control panel

An image forming apparatus comprising:

• a processor;
• and
• a control panel including a liquid crystal display (LCD), a touch screen, a coder-decoder (CODEC), a speaker, a microcontroller, and a diagnosis button,
• wherein, based on a selection of the diagnosis button, the microcontroller is to perform a diagnosis including displaying a test pattern on the LCD and outputting a sound at the speaker based on a touch being received on the touch screen.

An image forming apparatus comprising:

• a control panel including a microcontroller, an input device, a multiplexer, and an output device;
• and
• a processor to provide a first control signal for the output device to the multiplexer,
• wherein the microcontroller is to:
• receive an input signal to enter a diagnosis mode for the control panel, and
• based on entering the diagnosis mode, provide a second control signal for the output device to the multiplexer, and switch a state of the multiplexer to output the second control signal.