The black watch pen connected to pin 1 and 2, the red watch pen connected to pin 3 is about 1.5K, the red watch pen connected to pin 4 is about 5K, and the red watch pen connected to pin 5, 6, 7, and 8 is about 5K, which is normal. The above is only a reference, because its peripheral circuit is simple, as long as the measurement circuit is no problem, replace it