Safety Check Out Instructions - Sony KV-29AL40 Service Manual

After correcting the original service problem, perform the following
safety checks before releasing the set to the customer:
1. Check the area of your repair for unsoldered or poorly-
soldered connections. Check the entire board surface for solder
splashes and bridges.
2. Check the interboard wiring to ensure that no wires are "pinched"
or contact high-wattage resistors.
3. Check that all control knobs, shields, covers, ground straps, and
mounting hardware have been replaced. Be absolutely certain that
you have replaced all the insulators.
4. Look for unauthorized replacement parts, particularly transistors,
that were installed during a previous repair. Point them out to the
customer and recommend their replacement.
5. Look for parts which, though functioning, show obvious signs of
deterioration. Point them out to the customer and recommend
their replacement.
6. Check the line cords for cracks and abrasion. Recommend the
replacement of any such line cord to the customer.
7. Check the B+ and HV to see if they are specified values. Make
sure your instruments are accurate; be suspicious of your HV
meter if sets always havE low HV.
8. Check the antenna terminals, metal trim, "metallized" knobs,
screws, and all other exposed metal parts for AC Leakage. Check
leakage as described below.
To Exposed Metal
Parts on Set
0.15 µF
Fig. A. Using an AC voltmeter to check AC leakage.
SAFETY CHECK-OUT
AC
1.5 k Ω
Voltmeter
(0.75 V)
Earth Ground
LEAKAGE TEST
The AC leakage from any exposed metal part to earth ground and
from all exposed metal parts to any exposed metal part having a return
to chassis, must not exceed 0.5 mA (500 microampere). Leakage
current can be measured by any one of three methods.
1. A commercial leakage tester, such as the Simpson 229 or RCA
WT-540A. Follow the manufacturers' instructions to use these
instructions.
2. A battery-operated AC milliammeter. The Data PrecisioN 245
digital multimeter is suitable for this job.
3. Measuring the voltage drop across a resistor by means of a VOM
or battery-operated AC voltmeter. The "limit" indication is 0.75
V, so analog meters must have an accurate low voltage scale. The
Simpson's 250 and Sanwa SH-63Trd are examples of passive
VOMs that are suitable. Nearly all battery operated digital
multimeters that have a 2V AC range are suitable. (See Fig. A)
HOW TO FIND A GOOD EARTH GROUND
A cold-water pipe is guaranteed earth ground; the cover-plate
retaining screw on most AC outlet boxes is also at earth ground. 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. If a cold-
water pipe is not accessible, connect a 60-l00 watts 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 of
the line, the lamp should light at normal brilliance if the screw is at
ground potential. (See Fig. B)
Trouble Light
AC Outlet Box
Fig. B. Checking for earth ground.
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KV-29AL40/KV-29AL40A/KV-29AL40C
Ohmmeter
Cold-water Pipe