Read Sony SAVA-57 Service Manual online
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SAFETY CHECK-OUT
After correcting the original service problem, perform the follow-
ing safety checks before releasing the set to the customer:
Check the antenna terminals, metal trim, “metallized” knobs, screws,
and all other exposed metal parts for AC leakage. Check leakage as
described below.
ing safety checks before releasing the set to the customer:
Check the antenna terminals, metal trim, “metallized” knobs, screws,
and all other exposed metal parts for AC leakage. Check leakage as
described below.
LEAKAGE
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 microampers). Leak-
age current can be measured by any one of three methods.
1. A commercial leakage tester, such as the Simpson 229 or RCA
from all exposed metal parts to any exposed metal part having a
return to chassis, must not exceed 0.5 mA (500 microampers). Leak-
age 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
instruments.
instruments.
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 250 and Sanwa SH-63Trd are examples of a pas-
sive VOM that is suitable. Nearly all battery operated digital
multimeters that have a 2V AC range are suitable. (See Fig. A)
V, so analog meters must have an accurate low-voltage scale.
The Simpson 250 and Sanwa SH-63Trd are examples of a pas-
sive VOM that is suitable. Nearly all battery operated digital
multimeters that have a 2V AC range are suitable. (See Fig. A)
Fig. A. Using an AC voltmeter to check AC leakage.
SECTION 1
SERVICING NOTE
Connecting the Unit
• This unit is composed of a front speaker, transmitter and rear
speaker.
As the transmitter does not have its own power supply, connect it
to the front speaker as shown below when repairing.
As the transmitter does not have its own power supply, connect it
to the front speaker as shown below when repairing.
• Connection
Auto Power Control of Rear Speaker
• As the rear speaker is equipped with an auto power control, it will
set into the STANDBY state if it does not receive carrier wave
from the transmitter.
When performing repairs, connect the units according to the us-
ing environment.
from the transmitter.
When performing repairs, connect the units according to the us-
ing environment.
AC
voltmeter
(0.75V)
voltmeter
(0.75V)
1.5k
Ω
0.15
µ
F
Earth Ground
To Exposed Metal
Parts on Set
Parts on Set
MAIN board J103
REAR SPEAKER
REAR SPEAKER
FRONT
SPEAKER
transmitter
Rear speaker
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