Notes Of Schematic Diagram - JVC HM-DH30000U Service Manual

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NOTES OF SCHEMATIC DIAGRAM

Safety precautions
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 or k: k (1000 ), M: M
2) All capacitance values are in µF, (P: PF).
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
2
3
1
2
3
1
2
3
1
2
3
4
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 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
CHARTS AND DIAGRAMS
(1000k )
Removable connector
Wire soldered directly on board
Non-removable Board connector
Board to Board
Connected pattern on board
The arrows indicate signal path
Published in Heiloo Holland
SECTION 4
4) Indication on schematic diagram
Voltage Indications for REC and PB mode on the sche-
matic diagram are as shown below.
are
REC mode
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 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
C329 C330
0.1/50 0.1/50
R344
47K
R343
18K
5) Waveform indications
Waveform number
Oscilloscope Volts and Time/Division, Probe 10 : 1
Mode : REC or PB modes
1 2 3
2.5 1.8
(5.0)
PB and REC modes
(Voltage of PB and REC modes
are the same)
Measurement point
20 22 24
Waveform number
C331
WF25
11/10
R346
15K
R345
10K
Waveform name or
measurement point
WF25
ALC OUT
REC/PB 1.2 Vp-p Level : 1.2 Vp-p
50 mV/2 msec/DIV
29/11/2016
4-1