Sony XBR-55X900H Service Manual page 10

2021/04/27 23:25:57 (GMT+09:00)
1-6. Leakage Test
(To protect electric shock when customer touch the terminal.)
Leakage current can be measured by V: Voltmeter or oscilloscope (r.m.s. or peak
reading)
Stabilized power supply instrument and isolated voltage transformer:
Use too much current capacity and isolated voltage transformer does not need to use
stabilized power supply equipment.
Specification of RMS volt meter: Input resistance > 1 Mohm, Input capacitance < 200
pF, Frequency range: 15 Hz – 1MHz . Refer Figure 2. Isolated type volt -meter (FLUKE
8921A etc *1)
*1 Not use FLUKE 8920A that connected to protective earth by diode
# Leakage current of measurement instrument is less than 10μArms when under test
equipment AC plug is opened
# Set up the following condition and turn on the set. Applied voltage: Nominal input
voltage (Description on Nameplate)
# Measure the leakage current between one phase conductor and neutral for terminal A
and terminal B.
Read rms value, and then calculate to peak value PEAK VALUE =√2 RMS VALUE
Comply with the following requirement
Class II equipment (2-pin plug): for each terminal, the worst value of measurement
must not exceed AC 350uA peak).
Note: including AC adaptor, AC adaptor/DC operated unit combination
SAFETY NOTES
Figure 2 – Measuring network
for Leakage Current
SELF DIAGNOSTIC FUNCTION TROUBLESHOOTING
S A F E T Y N O T E S
1-7. How to Find a Good Earth Ground
1)A cold-water pipe is a guaranteed earth ground; the cover-plate retaining screw on
most AC outlet boxes is also at earth ground.
2)If the retaining screw is to be used as your earth ground, verify that it is at ground by
measuring the resistance between it and a cold-water pipe with an ohmmeter. The reading
should be zero ohms.
3)If a cold-water pipe is not accessible, connect a 60- to 100-watt trouble- light (not a neon
lamp) between the hot side of the receptacle and the retaining screw. Try both slots, if
necessary, to locate the hot side on the line; the lamp should light at normal brilliance if the
screw is at ground potential (see Figure 3).
1-8. Lead Free Information
The circuit boards used in these models have been processed using Lead
Free Solder. The boards are identified by the LF logo located close to the
board designation.
Figure 4: LF Logo
The servicing of these boards requires special precautions. It is
strongly recommended to use Lead Free Solder material in order to
guarantee optimal quality of new solder joints.
SERVICE ADJUSTMENT
Figure 3. Checking for earth
ground.
Figure 5: LF logo on circuit board
DIAGRAM HANDLING GUIDE
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SYS SET