1. A+25V passes C941 and R983 and adds an instantaneous high level at the Pin 12 of
N907D when this unit gets started. According to the above characteristics, the Pin 14 sends
out a voltage which is comparatively closer to the voltage of the power supply B+23V. This
voltage measures about +17V and is fed back to the Pin 12 through R960. Then this voltage
is divided into about +8.5V by the resistor R959. That is to say, the inphase voltage of the
calculating amplifier N907D keeps at about +8.5V. At the same time, +8.5V is divided by
VD903, R971 and R972 and the voltage of the Pin13 of N907D measures about +7.5V. That
is to say, the inphase opposition of N907D keeps at about +7.5V. At this moment, the inphase
voltage (ca +8.5V) of the calculating amplifier N907D is higher than the inphase opposition
voltage (ca +7.5V). The output Pin 14 also keeps at about +17V. Therefore, the above status
retains. The Pin 14's high level of +17V passes R961 and reaches the display screen and
lightens the VCD indicator. The 0 level is obtained at the controllers A&B of the electronic
switch in the input circuit. According to the real value table, the electronic switch elects the
VCD input mode. C941 is the open restoration capacitor because of which the input mode
is switched to the default VCD. The inphase opposition voltage of another three calculating
amplifiers is +7.5V (Their inphase opposition ports are connected together), but the positive
voltage doesn't exist in the inphase ports. According to the voltage comparing characteristics,
there is not the high level output in the inphase opposition ports. The other three input modes
are shut off.
2. When we select other input modes, for instance, selecting DVD mode, we press the switch
S903. The voltage of B+23V passes R984, S903 and R965 and is divided into about +18V
voltage which is sent to the inphase port of N907A. At the same time, the +18V voltage is
divided by VD905, R971 and R972 and there is about +17V level input at the inphase
opposition port of N907A. The high level from N907A is fed back by R966. When loosening
S903, N907's working voltages (The working principle is the same as that in the above-
mentioned VCD mode.) are as follows: +8.5V at inphase port, +7.5V at inphase opposition
port, +17V at output port. As mentioned before, the inphase opposition port's voltage is +17V
when the switch is turned on. This voltage also reaches the calculating amplifier N907 in the
VCD mode. Because the inphase port of N907D r8.5V and the inphase opposition
port increases to +17V, the original output mode is breached and the high level cannot be
sent out. Therefore, the VCD mode is shut off. At this moment, the high level of +17V of
N907A's output is divided into two lines: One line is sent to the display screen by R967 to
lighten the DVD indicator. Another line is divided by VD908, R974 and R975 and sent to the
Port B of the electronic switch in the input circuit. Now, the Port A of N401 is 0 level and the
Port B of N401 is 1 level. According to the real value table, the electronic switch selects the
DVD mode, and the whole process is finished. When selecting other modes and pressing
other switches, the caused motions are the same as above ones.
- 8 -
- 19 -
8.2 Front Panel's Control Board
8.2.1 Main Parts List of The Front Panel's Control Board
NO.
DESCRIPTION
SPECIFICATIONS / PART
NUMBER
LOCATION SPECIFICATIONS
1
CARBON FILM
RESISTOR
1/4W470
¦ ¸
±5% SHAPED
10
R979,R990,R994,R997,R1000,R1003,R1006,R1009,R1010
2
CARBON FILM
RESISTOR
1/4W1K±5% SHAPED 10
R601,R602,R961,R964,R967,R970,R982,R988,R1016,
R1012,R1007,R985,R1014,R642
3
CARBON FILM
RESISTOR
1/4W1.5K±5% SHAPED 10 R607
4
CARBON FILM
RESISTOR
1/4W2.2K±5% SHAPED 10 R629,R1004,R977,R978
5
CARBON FILM
RESISTOR
1/4W3.3K±5% SHAPED 10 R991,R621
6
CARBON FILM
RESISTOR
1/4W3.9K±5% SHAPED 10 R606
7
CARBON FILM
RESISTOR
1/4W4.7K±5% SHAPED 10 R1001,R611,R946,R640
8
CARBON FILM
RESISTOR
1/4W5.6K±5% SHAPED 10 R639
9
CARBON FILM
RESISTOR
1/4W10K±5% SHAPED 10
R901,R902,R905~R908,R910~R913,R915,R916,R919,
R922,R957,R971,R989,R995,R981,R987,R1015,R604,
R613,R614,R616,R620,R622,R625,R627,R630~R634,
R636,R643
10
CARBON FILM
RESISTOR
1/4W12K±5% SHAPED 10 R608,R624
11
CARBON FILM
RESISTOR
1/4W15K±5% SHAPED 10 R623,R626,R628,R619
12
CARBON FILM
RESISTOR
1/4W20K±5% SHAPED 10 R975,R976,R609,R615
13
CARBON FILM
RESISTOR
1/4W22K±5% SHAPED 10 R993,R996,R999,R1002,R984,R1008,R1005,R909,R914
14
CARBON FILM
RESISTOR
1/4W47K±5% SHAPED 10 R973,R974,R980,R983,R959,R960,R603,R618,R644
15
CARBON FILM
RESISTOR
1/4W100K±5% SHAPED
10
R903,R904,R925,R926,R962,R965,R968,R972,R963,
R966,R969,R992,R958,R605,R638
16
CARBON FILM
RESISTOR
1/4W220K±5% SHAPED
10
R1011,R637
17
CARBON FILM
RESISTOR
1/4W470K±5% SHAPED
10
R927,R617
18
CARBON FILM
RESISTOR
1/4W30K±5% SHAPED 10 R920,R921,R923,R924
19
CARBON FILM
RESISTOR
1/4W8.2K±5% SHAPED 10 R998,R610,R612,R641
20
CARBON FILM
RESISTOR
1/2W2K±5
£ ¥
SHAPED 12.5 R986
21
CARBON FILM
RESISTOR
1/2W150
¦ ¸
±5% SHAPED
12.5
R635
22
ROTATING
POTENTIO-
METER
A145GOED-H1B503-007
RP901
ROTATING
POTENTIO-
METER
A145GOED-H1B503-007-
01
RP901
ROTATING
POTENTIO-
METER
A145GOED-H1B503-007-
02
RP901
23
ROTATING
POTENTIO-
METER
A145GOED-H1B503-008
RP902,RP903