A circuitry testing method, comprising: providing a circuit board needing testing; applying a potential (160) to the circuit board needing testing so that the circuit board works and operating elements of the circuit board needing testing emit infrared rays; testing an intensity of radiation of the infrared rays using an infrared sensor (110); converting the radiation intensity to RGB (red, green, blue) data signals in order to form a diagnostic infrared image, using a processor (130); providing a standard infrared image; comparing the diagnostic infrared image with the standard infrared image; and determining whether the circuit board is defective according to the comparison.