Jvc SRVS 20 Schematic

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SECTION 4
CHARTS AND DIAGRAMS

NOTES OF SCHEMATIC DIAGRAM

Safety precautions

The Components identified by the symbol A are
critical for safety. For continued safety, replace safety
critical components only with manufacturer's recom-
mended parts.

1. Units of components on the schematic diagram

Unless otherwise specified.

1) All resistance values are in ohm, 1/6 W, 1/8 W (refer to
parts list).
Chip resistors are 1/16 W.

K or k: kQ (1000(2), M: MQ (1000kQ)

2) All capacitance values are in uF, (P: PF).

3) All inductance values are in pH, (m: mH).

4) All diodes are 188133, MA165 or 1N4148M (refer to parts
list).

2. Indications of control voltage
AUX : Active at high
AUX orAUX(L) : Active at low

3. Interpreting Connector indications

Removable connector

% Wire soldered directly on board

Non-removable Board connector

Board to Board

6
Connected pattern on board
The arrows indicate signal path

4. Voltage measurement

1) Video circuits
REC : Colour bar signal in SP mode, normal VHS mode
PB : Alignment tape, colour bar SP mode, normal VHS
mode
- : Unmeasurable or unnecessary to measure
2) Audio circuits
REC : 1KHZ, -8 st sine wave signal in SP mode, Nor-
mal VHS mode
PB : REC then playback it
3) Movie Camera circuits
Measured using a correctly illuminated gray scale or colour
bar test charts in the E-E mode

4) Indication on schematic diagram
Voltage Indications for REC and PB mode on the sche-
matic diagram are as shown below.

REC mode4>25 1.8
(5.0)

LPB and REC modes
(Voltage of PB and REC modes
are the same)

PB mode
Note: If the voltages are not indicated on the schematic
diagram, refer to the voltage charts.

5. Waveform measurement

1) Video circuits
REC : Colour bar signal in SP mode, normal VHS mode
PB : Alignment tape, colour bar SP mode, normal VHS
mode
2) Audio circuits
REC : 1KHz, -8 st sine wave signal in SP mode, normal
VHS mode
PB : REC then playback it
3) Movie Camera circuits
Measured using a correctly illuminated gray scale or colour
bar test chatrs in the E-E mode

4) Indication on schematic diagram
Waveform indications on the schematic diagram are as
shown below.

Measurement point

Waveform number

5) Waveform indications
Waveform number Waveform name or
measurement point

WF25 ALC OUT

REC/PB 1.2 Vp-p47 Level: 1.2 Vp-p
50 mV/2 msec/DIV

Oscilloscope Volts and Time/Division, Probe 10 : 1
Mode : REC or PB modes

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6. Signal path Symbols
The arrows indicate the signal path as follows.

l:> Playback signal path

C} Playback and recording signal path

- Recording signal path
(including E-E signal path)

C>I> Capstan servo path
-> Drum servo path

(Example)
|:> R-Y Playback Fl-Y signal path

- Y Recording Y signal path

7. Indication of the parts for adiustments

The parts for the adjustments are surrounded with the circle as
shown below.

@@

8. Indication of the parts not mounted on the circuit board
OPEN is indicated by the parts not mounted on the circuit
board.

R216

AAA,-
OPEN

CIRCUIT BOARD NOTES

1. Foil and Component sides
1) Foil side (B side) :
Parts on the foil side seen from foil face (pattern face)
are indicated.
2) Component side (A side) :
Parts on the component side seen from component face
(parts face) indicated.

2. Parts location guides
Parts location are indicated by guide scale on the circuit board.

REF No.| LOCATION
IC <7iCategory: IC
|0101|B|CI 6A

B : Foil Side

(A : Component side) Horizontal A" zone

C : Chip component Vertical "6" zone

(D : Discrete component)

Note:
For general information in service manual, please refer
to the Service Manual of GENERAL INFORMATION Edi-
tion 4 No. 820540 (January 1994).