LG MV1611WW Service Manual page 26

COMPONENTS
H.V.CAPACITOR
H.V.DIODE
(RECTIFIER)
1. Check DC 9V battery before performing tests.
2. Select the DCV scale on the meter.
3. Using the meter, battery, and jump wire, connect
the items as illustrated in figures.
• Terminal to terminal
• Terminal to case
STEP 1. Test the diode to see if it is shorted.
Procedure:
1. Select the ohm scale on the meter.
2. Place the meter leads across the diode as pictured in
Figure 1. The reading should be "40M," "OL," or a
reading of infinity.
3. Reverse the meter leads. The reading should again
indicate a reading of infinity. If the diode shows
"infinity" in BOTH directions, it is NOT shorted.
4. If the diode is not shorted, proceed to step 2.
STEP 2. Test the diode for forward biasing.
Procedure:
1. Select the DCV scale on the meter.
2. Using the meter, battery, and jumper wire, connect the
items as illustrated in Figure 2.
This has the positive side of the battery connected to
the cathode of the diode.
3. The diode should be forward biased therefore a voltage
reading of approximately 4.7 VDC to 6.4 VDC will be
read depending on meter, battery strength, etc. (Note: If
the meter leads were reversed, a negative voltage of
the same amount would be seen.)
STEP 3. Test the diode for reverse biasing.
Procedure:
1. Using the same scale on the meter, connect the
positive side of the battery to the anode of the diode
as illustrated in Figure 3.
2. The diode should be reverse biased therefore a
reading of 0 volt or a value displayed in mV will be
seen. (The display will be erratic changing values
rapidly in the mV scale.)
7-15
TEST RESULTS
Normal:
Approximately 9V
Abnormal :
Approximately 0V
Normal:
Approximately 0V or
a value displayed in
mV Will be seen.
Normal:
Approximately
4 .7-6.4V
Normal:
Approximately 0V