How to use a multimeter to measure the quality of a rectifier

From the figure, we can draw the conclusion: AC-AC: positive and negative are not connected. Positive-negative: negative to positive is connected, but positive to negative is not connected. AC-positive-negative: AC to positive is connected, but negative to AC is connected. If there is any other connection, it is bad.

There are two ways to test the quality of the ballast:

1. Power-on test; 2. Block static test.

The first one: First you prepare a 220v40w light bulb, connect it in series with the ballast, listen carefully to the sound of the ballast and observe the brightness of the bulb. If you find that the bulb is not bright or the filament of the bulb is dark red and the brightness of the bulb remains unchanged (referring to the brightness of the bulb after being connected to the power supply in parallel under normal circumstances), it means that the ballast is faulty.

Fault analysis:

1. The bulb does not light up: there is a circuit breaker (open circuit) fault inside the ballast;

2 The filament is dark red and serious: there is a virtual connection inside (poor contact) 3 The brightness of the bulb remains unchanged: there is an internal short circuit fault.

The second type: static test, adjust the multimeter to the resistance block r*1000, connect the test leads to the ballast. If the reading is 0, there is an internal short circuit; if the reading is infinity, there is an internal open circuit, or there is a reading but it is not too large, it is normal.