Charts And Diagrams; Notes Of Schematic Diagram; Circuit Board Notes - JVC GR-FXM270A Service Manual

CHARTS AND DIAGRAMS

NOTES OF SCHEMATIC DIAGRAM

Safety precautions
5
The Components identified by the symbol
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: KΩ (1000Ω), M: MΩ (1000KΩ)
2) All capacitance values are in µF, (P: PF).
4
3) All inductance values are in µH, (m: mH).
4) All diodes are 1SS133, MA165 or 1N4148M (refer to parts
list).
2. Indications of control voltage
AUX : Active at high
AUX or AUX(L) : Active at low
3. Interpreting Connector indications
1
Removable connector
2
3
3
1
Wire soldered directly on board
2
3
1
Non-removable Board connector
2
3
1
2
Board to Board
3
2
4
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
1
REC : 1KHz, –8 dBs 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
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SECTION 4
4) Indication on schematic diagram
Voltage Indications for REC and PB mode on the sche-
matic diagram are as shown below.
are
1 2
REC mode 2.5 1.8
(5.0)
PB and REC modes
(Voltage of PB and REC modes
PB mode
are the same)
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 dBs 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.
16 18 20 22 24
C329 C330
0.1/50 0.1/50
C331 WF25
11/10
R344
47K
R346
15K
R343 R345
18K 10K
5) Waveform indications
Waveform number
WF25 ALC OUT
REC/PB 1.2 Vp-p
50 mV/2 msec/DIV
Oscilloscope Volts and Time/Division, Probe 10 : 1
Mode : REC or PB modes
B
C
6. Signal path Symbols
The arrows indicate the signal path as follows.
Playback signal path
Playback and recording signal path
Recording signal path
(including E-E signal path)
3
Capstan servo path
Drum servo path
(Example)
R-Y
Playback R-Y signal path
Y
Recording Y signal path
7. Indication of the parts for adjustments
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
Measurement point
board.
R216
OPEN
Waveform number
Waveform name or
measurement point
Level : 1.2 Vp-p
D E
4-1 4-2
4-2
4-1

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
IC101 B C 6 A
B : Foil side
(A : Component side)
C : Chip component
(D : Discrete component)
Note:
For general information in service manual, please refer
to the Service Manual of GENERAL INFORMATION Edi-
tion 4 No. 82054D (January 1994).
F
G
Category : IC
Horizontal "A" zone
Vertical "6" zone
H
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