Table Of Contents - Sony MDS-JB940 Service Manual
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Also See for MDS-JB940:
- Operating instructions manual (120 pages) ,
- Operating instruction (59 pages) ,
- Specifications (2 pages)
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··································································· 17
MAIN Section ································ 31
6-2. Block Diagram
DISPLAY/POWER Section ··········· 32
6-4. Circuit Board Location ················································ 33
6-5. Waveforms ··································································· 34
6-8. Schematic Diagram
6-11. Schematic Diagram
6-12. Schematic Diagram
6-13. Schematic Diagram
6-15. Printed Wiring Board
6-16. Printed Wiring Board
6-17. Schematic Diagram
6-18. Schematic Diagram
6-20. IC Block Diagrams ······················································ 48
6-21. IC Pin Function Description ········································ 53
8. ELECTRICAL PARTS LIST
2
········································ 4
······························ 22
BD Board ····························· 35
BD Board (1/2) ······················· 36
BD Board (2/2) ······················· 37
HP Board/KEY Board ·········· 38
HP Board/KEY Board ············ 38
MAIN Board (1/3) ·················· 39
MAIN Board (2/3) ·················· 40
MAIN Board (3/3) ·················· 41
MAIN Board (Side A) ·········· 42
MAIN Board (Side B) ·········· 43
PANEL Section ···················· 44
PANEL Section ······················· 45
AC Board ································ 46
AC Board ······························ 47
······················································ 60
······································· 64
SAFETY CHECK-OUT
After correcting the original service problem, perform the
following 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 microamperes).
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
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 passive VOM that is suitable. Nearly all battery operated
digital multimeters that have a 2V AC range are suitable. (See
Fig. A)
To Exposed Metal
Parts on Set
0.15 µF
Fig. A. Using an AC voltmeter to check AC leakage.
MODEL IDENTIFICATION
- BACK PANEL -
Model
AEP, UK models
Canadian model
US model
AC
Voltmeter
1.5 kΩ
(0.75 V)
Earth Ground
Part No.
Part No.
4-228-507-0s
4-228-507-1s
4-228-507-2s
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