Inspection method for the quality of light bulbs: 1. Test whether the light bulb is DC or shunt. AC lamps do not have positive or negative poles, so the filament of the AC light bulb is "one wire" connected; The filament of a DC lamp is disconnected in the middle and has a larger end, which is the positive electrode; If one end is smaller, it is the negative electrode. 2. Look outside to see if there is a blackened area on the front end of the lamp core. Generally, if the lamp core is damaged, it will be at the bottom. Upon closer inspection, there may be cracks or white bubbles. 3. Actual measurement 1). It cannot be measured with a digital meter and there is no display of resistance value; Use a simulated mechanical meter to measure the two pins of the light bulb in the resistance range of 100K. The needle of the meter slightly moves at the far left end, which is basically normal. If the resistance value is low in the 100K range, the basic light may have problems or be caused by aging during use. Factory testing uses specialized lighting equipment to practice measuring lighting, and repair points cannot purchase lighting equipment. 2) Another method is to purchase a stabilizer (high-voltage rectifier) for 35W or 50W cars or motorcycles online to directly light up the lights. If the projector bulb can be fully lit, it is the number one bulb. Conversely, if the bulb is damaged, it will be protected by the stabilizer after flashing a few times due to severe aging