MS021 – your helper in diagnosing of alternators

If the alternator diagnostics on a bench or in a car reveals a high value of alternating current component, it indicates a fault in either the diode bridge or the stator windings.

Usually to check the diode bridge use a multimeter, less often, use a test lamp of a few watts and a battery or laboratory power supply in the mode of current limitation.  In this case, each diode has to check twice, supplying current in the forward and reverse direction, which is not always convenient. An ordinary multimeter checks with a current of about 0.002A. This value of current is too small, compared to the operating currents of the diode.  Therefore, this test allows you to identify only obvious problems with the diode in the form of a short circuit or open circuit. In case of using avalanche diodes (a kind of stabilitron) in diode bridges, their full evaluation by multimeter is impossible, because multimeter gives out too low voltage in comparison with breakdown voltage of avalanche diode. Thus, diagnostics of the diode bridge by conventional methods, using improvised means, is very labour-intensive and will not be accurate.

To quickly and accurately assess the performance of diode bridges in automotive alternators, MSG Equipment has developed the MS021 Diode Bridge Tester, which tests the diode with a current limit of 0.9A  and a voltage of 30V to accurately assess its condition and type. There is no need for the operator to reverse polarity.

The MS021 diagnostic tester can determine:

• diode breakdown;
• the presence of poor contact of the diode with the conductive busbars;
• type of diode (ordinary diode, avalanche diode);
• diode degradation (increased forward voltage drop);
• back breakdown voltage of avalanche diode;

So, using the tester MS021, you can not only assess the state of the diode bridge, but also determine all the necessary parameters to carry out the selection of diode to replace the failed diode. In addition, usually defective diode bridges are left in the workshop and can become a free source of diodes. In order to ensure a quality repair, it is very important that the characteristics of the diodes in the bridges are close to each other.

 The ability to detect diode bridge degradation with the MS021 diode bridge tester allows us to repair alternators as quickly and efficiently as possible, thereby ensuring customer confidence and loyalty.

 The MS021 diode bridge tester allows us to repair alternators as quickly and efficiently as possible, thereby ensuring customer confidence and loyalty.