How to check the bridge rectifier ?
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car consists of many parts and assemblies, and eventually they may deteriorate, wear out and fail.Most motorists can easily repair the engine or one of the mechanical components, but have difficulty repairing electrical components.The electric part of the car for many motorists is poorly understood and, therefore, even if minor faults they seek help in auto repair.
Sometimes motorists encounter a problem when the car battery is not charged, or simply spoiled due to electrolyte boiling.Often the cause of these problems are a problem with the car's alternator diode bridge.Let's find out how to test a diode bridge.
What is Diode bridge?
First, you need to explain what a diode bridge and why it is needed.Diode bridge - an electrical circuit that is designed to "straighten" the AC.It is necessary to convert the alternating current, which is produced by the car generator in a pulsating, which charges the car battery.
battery can not be charged by AC directly from the generator.Therefore, in cases of failure of the diode bridge, or the battery will not charge, or completely fail.
Checking the diode bridge
How to check a car alternator diode bridge, if the hand is not a tester?To do this you need two wires and a lamp for 12 volts (small as possible).The procedure is very simple:
- Remove the protective cover from the generator and the battery, connect the negative terminal of the diode bridge plate.
- One wire from the lamp plug to the battery positive terminal, and the second to touch the rest of the diodes and output terminals to the points where the stator winding is connected.
- If some of the outputs of the bulb lights up, it means the diode is broken and must be replaced.
Now let's check a diode bridge for open contacts:
- Negative lamp wire to the negative terminal of the battery and just palpate wire "plus" contacts of the diode bridge.In this case, the lamp should light up.If in some place it is not lit or dimly lit - here the contacts open.
- If you have a tester (multimeter), a diode bridge is necessary to remove completely.
- Put Tester proring mode.If your tester has such function, set it to 1 ohm mode.
- Check probes tester diode contacts, and then change the test leads reversed.If the tester gives a signal to the one direction, while another "silence" (or one direction shows 400-800 ohms and the next 0), then the diode is good.
- If the tester shows nothing and does not signal - a diode is interrupted.
- If the signal is in the two directions or in both directions the same resistance - diode breakdown.
also useful information on this topic can be found in the article How to check diodes.
Causes damage to the diode bridge
In most cases, a diode bridge is out of order for two reasons - it gets water or when the car plant from another car battery (if equipped with the terminals on the battery polarity confuse them).We also recommend to read the article integrity check generator diode bridge for more information.