MAC TOOLS EM721 Manual Del Usuario página 48

Meter setup to measure alternator output voltage:
•
Set the rotary switch to voltage ( ) setting.
•
Press the "DC/AC" button until " " appears on the display.
•
Insert the black lead in the "COM" jack.
•
Insert the red lead in the "
Press the "REC" button (selects the MAX.MIN.AVG function).
Connect:
•
Black test probe to the negative (-) battery post.
•
Red test probe to the battery (+) terminal on the back of the alternator.
Start the engine and run it at 2,000 RPMs. A reading of 13.5V to 15.5V is an acceptable charging rate.
A good alternator will maintain at least 13.6V at the rated current output.
Alternator Field Current Test
Corroded or worn brushes (or terminals) limit the alternator's field current and cause a low alternator output
current. To check the field current, load the alternator to the rated output current with a battery load tester and
measure the field current by using a DC clamp-on current probe (optional accessory) or use the "A" input jack
on the meter.
Meter setup to measure alternator field current:
•
Set the rotary switch to amps (10 ) setting.
•
Press the "DC/AC" button until " " appears on the display.
•
Insert the black lead in the "COM" jack.
•
Insert the red lead in the "A" jack.
Turn all vehicle accessories off.
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" jack.
Red
Positive
12V Battery
Alternator
Cable
Black
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