The 555 is connected to a typical multivibrator with an oscillation frequency of about 3Hz. The third pin is the output end, if the 555 integrated circuit is good, the light-emitting diode VD will blink at a frequency of 3Hz, that is, three times a second. If the LED is on or off, the 555 is bad. Of course, we must first ensure that these peripheral components are good and in good contact.
In actual use, you can weld an 8-pin IC socket first, and plug 555 in to determine whether it is good or bad.
555 chip measurement method:
The first step is to use the milliampere file of the multimeter to string it between the power supply and the pin of the ne555p, if the measured value is static current,
The second step is to multiply the measured static current by the power supply voltage, which is the static power consumption. In general, the static current is qualified if it is less than 8 mA.