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7-1
SECTION 7
ADJUSTMENTS
1
2
3
4
Mode
SP
SP
EP
EP
Video signal
Color bar
Monoscope
Color bar
Monoscope
Audio signal
(HiFi/Normal)
400 Hz
Time
Seven minutes
Three minutes
Seven minutes
Three minutes
7-1. MECHANICAL ADJUSTMENTS
Refer to the SERVICE MANUAL of VHS MECHANICAL AD-
JUSTMENT VI.
JUSTMENT VI.
7-2. ELECTRICAL ADJUSTMENTS
2-1.
PRE-ADJUSTMENT PREPARATIONS
Necessary items and indications for total adjustment of electric
circuit of this machine will be described in this chapter.
circuit of this machine will be described in this chapter.
2-1-1.
Instruments to be Used
1) Color TV
2) Oscilloscope 1 or 2 phenomena, band more than 30 MHz, de-
2) Oscilloscope 1 or 2 phenomena, band more than 30 MHz, de-
lay mode, as provided.
3) NTSC pattern generator
4) PAL pattern generator
5) Digital voltmeter
6) Audio level meter
7) Audio noise meter
8) Audio generator
9) Attenuator
10) Alignment tape
4) PAL pattern generator
5) Digital voltmeter
6) Audio level meter
7) Audio noise meter
8) Audio generator
9) Attenuator
10) Alignment tape
Part Code: 8-192-605-36 KRV-51P (PAL)
Part Code: 8-192-605-32 KRV-51N2 (NTSC)
Part Code: 8-192-605-32 KRV-51N2 (NTSC)
2-1-2.
Connection
Unless otherwise specified, connect and adjust the measuring in-
struments as shown in the following diagram.
struments as shown in the following diagram.
During the adjustment, see the Parts Arrangement
Diagram for Adjustments on Page 7-6.
Diagram for Adjustments on Page 7-6.
Fig. 7-2-2
2-1-4.
Alignment Tapes
[Alignment Tape (KRV-51N2 / KRV-51P)]
2-1-3.
Set-up of Adjustment
In this adjustment, PAL or NTSC pattern generator is connected
with LINE input signal terminal. When check to tuner, connected
AERIAL terminal. Check that the amplitudes of video signal SYNC
signal, of picture portions, and of burst signals are flat at
approximately 0.3, 0.7 and 0.3 V, respectively, and that the level
ratio of the burst signal and “red” signal are 0.30: 0.66. Fig. 7-2-2.
shows video signals (color bars) used in adjusting the video section.
with LINE input signal terminal. When check to tuner, connected
AERIAL terminal. Check that the amplitudes of video signal SYNC
signal, of picture portions, and of burst signals are flat at
approximately 0.3, 0.7 and 0.3 V, respectively, and that the level
ratio of the burst signal and “red” signal are 0.30: 0.66. Fig. 7-2-2.
shows video signals (color bars) used in adjusting the video section.
PAL
NTSC
Video output
(75
Ω
)
Pattern generator
VCR
VIDEO LINE IN
Monitor TV
VIDEO LINE OUT
SLV-ED8/EZ8/EZ9
Fig. 7-2-1
2-1-5.
Specified I/O Level and Impedance
Input/output terminal
Video inputs
LINE IN
: phono jack
1 Vp-p, 75
Ω
, unbalanced, sync negative
Audio inputs
LINE IN
: phono jacks
47 kW, –7.5 dBs (0 dBs = 0.775 Vrms)
More than 10 kW, –4 dBs
More than 10 kW, –4 dBs
Video outputs
LINE OUT : phono jack
1 Vp-p, 75
1 Vp-p, 75
Ω
, unbalanced, sync negative
Audio outputs
LINE OUT : phono jacks
–7.5 dBs at load impedance 47 k
–7.5 dBs at load impedance 47 k
Ω
Output impedance : less than 10
Ω
7-2
2-1-6.
Adjusting Sequence
Make the electrical adjustment in the following sequence.
2-3.
SERVO SYSTEM Adjustment
2-3-1.
RF Switching Position Adjustment
(MA-325 Board)
(MA-325 Board)
Purpose:
Adjust the interval between A ch and B ch of tape playback out-
put.
Improve the interchangeability with other tapes and sets.
When it is out of order, the interval appears on the screen, the
screen is disturbed.
Adjust the interval between A ch and B ch of tape playback out-
put.
Improve the interchangeability with other tapes and sets.
When it is out of order, the interval appears on the screen, the
screen is disturbed.
Mode
PB
Signal
Alignment tape SP mode
color bar
color bar
Measurement Point
CH1: Pin 2 of CN501
CH2: Pin 3 of CN501
(RF SWP)
CH2: Pin 3 of CN501
(RF SWP)
Measuring Instrument
Oscilloscope
Specified Value
6.5 ± 0.5 H (416 ± 32 µsec)
PAL
PAL
6.5 ± 0.5 H (410 ± 32 µsec)
NTSC
NTSC
Adjusting Method:
1) Connect MA-325 board JS161 to the GND for about 1 second
1) Connect MA-325 board JS161 to the GND for about 1 second
to activate the RF switching position adjustment mode.
2) Check appear “rFxx” on FL display.
3) Using the PROGRAM + and – buttons, adjust to 6.5 ± 0.5 H.
4) Press the PAUSE button.
3) Using the PROGRAM + and – buttons, adjust to 6.5 ± 0.5 H.
4) Press the PAUSE button.
Fig. 7-2-3.
Mode
E-E
Measuring Instrument
Digital voltmeter
–10 V check
Measurement Point
Pin 9 of CN600
Specified Value
–10.3 ±0.8 V
+6 V check
Measurement Point
Pin 7, 8 of CN600
Specified Value
5.9 ± 0.2 V
+13 V check
Measurement Point
Pin 2, 3 of CN600
Specified Value
13.3 ± 0.5 V
+35 V check
Measurement Point
Pin 1 of CN600
Specified Value
38.0 ± 3.0 V
2-2.
POWER SUPPLY ADJUSTMENT
2-2-1.
Power Supply Check
(SR-718 BOARD)
(SR-718 BOARD)
Checking Method:
1) Confirm that each voltage meets its specified value.
1) Confirm that each voltage meets its specified value.
2-2-2.
+6 V Adjustment
(SR-718 BOARD)
(SR-718 BOARD)
Approx. 1 Vp-p
Approx. 5 Vp-p
V
enargement
CH2
CH1
CH2
CH1
Vertical sync. signal
6.5
±
0.5 H
(416
±
32
µ
sec) PAL
(410
±
32
µ
sec) NTSC
Mode
REC or PB
Measuring Instrument
Digital voltmeter
Measurement Point
Pin 7, 8 of CN201
Adjusting Element
RV201
Specified Value
5.9 ± 0.2 V
Checking power supply
Servo system adjustment
Audio system adjustment
Video system adjustment
7-3
2-4.
AUDIO SYSTEM ADJUSTMENTS
• Adjust both Lch and Rch.
[Connection]
Fig. 7-2-4.
2-4-1.
Hi-Fi Audio System Adjustment
• Set switches and knobs to the following positions to make ad-
justment unless otherwise specified.
INPUT SELECT switch ................... LINE
AUDIO MONITOR .......................... STEREO
INPUT SELECT switch ................... LINE
AUDIO MONITOR .......................... STEREO
[Adjustment Sequence]
1. AF Switching Position Adjustment
2. Frequency Responce Check
3. Overall Level Characteristic and Distortion Factor
1. AF Switching Position Adjustment
2. Frequency Responce Check
3. Overall Level Characteristic and Distortion Factor
Check
4. Overall S/N Check
1.
AF Switching Position Adjustment (MA-325 Board)
Purpose:
Adjust the interval between A CH and B CH of tape playback
output. Improve the interchangeability with other tapes and sets.
When it is out of order, noisy sound is increased and big noise is
heard.
Adjust the interval between A CH and B CH of tape playback
output. Improve the interchangeability with other tapes and sets.
When it is out of order, noisy sound is increased and big noise is
heard.
Mode
PB
Signal
Alignment tape SP mode
color bar
color bar
Measurement point
CH2: Pin 1 of CN341
CH1: Pin 3 of CN501
CH1: Pin 3 of CN501
Measuring Instrument
Oscilloscope
Specified Value
Fig. 7-2-5
Adjusting Method:
1) Connect MA-325 board JS161 to the GND for about 1 second
to activate the RF switching position adjustment mode.
2) Press the PAUSE button to activate the AF switching position
adjustment mode.
3) Check appear “HFxx” on FL display.
4) Using the PROGRAM + and – buttons, minimize a chipped
4) Using the PROGRAM + and – buttons, minimize a chipped
portion. At this time, confirm that a noisy sound is not heard.
5) Press the PAUSE button.
6) Press the EJECT button.
6) Press the EJECT button.
Fig. 7-2-5.
2.
Frequency Responce Check
Purpose:
Confirm that the frequency characteristic is within the specifica-
tion.
Confirm that the frequency characteristic is within the specifica-
tion.
Mode
REC and PB (SP, EP, LP
mode)
mode)
Signal
400 Hz, –7.5 dBs
20 Hz, –7.5 dBs
20 kHz, –7.5 dBs
20 Hz, –7.5 dBs
20 kHz, –7.5 dBs
Measurement point
Audio output terminal
Measurement equipment
Audio level meter
Specified value
0 ± 2 dB
Note:
Tape path adjustment must have been completed.
Confirmation Method:
1) Supply a signal of 400 Hz, –7.5 dBs to both L and R channels
1) Supply a signal of 400 Hz, –7.5 dBs to both L and R channels
of Audio Line Input.
2) Connect the audio level meter to the Audio Line Output.
3) Adjust the attenuator so that the audio level meter will indi-
3) Adjust the attenuator so that the audio level meter will indi-
cate –7.5 dBs.
4) Make recording.
5) Set an audio line input signal to 20 Hz and make recording.
6) Set an audio line input signal to 20 kHz and make recording.
7) Playback a recorded portion, and measure output levels at 400
5) Set an audio line input signal to 20 Hz and make recording.
6) Set an audio line input signal to 20 kHz and make recording.
7) Playback a recorded portion, and measure output levels at 400
Hz and 20 Hz and 20 kHz.
8) Confirm that the 20 Hz and 20 kHz playback output level within
a range of the 400 Hz playback output level 0 ± 2 dB.
Audio
generator
generator
Attenuator
600
Ω
47 k
Ω
VCR
Audiolevel meter or
distortion meter
AUDIO LINE OUT
AUDIO LINE IN
Feed signal both
channelssimultaneously.
Feed signal both
channelssimultaneously.
CH2
CH1
RF SWP
RF SWP
OK
NG
7-4
3. Overall Level Characteristic and Distortion Factor
Check
Purpose:
Check the record level, play level, and distortion factor against the
reference input.
Check the record level, play level, and distortion factor against the
reference input.
Mode
REC and PB (SP mode)
Signal
400 Hz, –7.5 dBs
Measurement point
Audio output terminal
Measurement equipment
Audio level meter and
distortion factor meter
distortion factor meter
Specified value
Playback level: –7.5 ± 2 dBs
Distortion factor: 1% or less
Distortion factor: 1% or less
Confirmation Method:
1) Supply an audio signal of 400 Hz, –7.5 dBs simultaneously to
1) Supply an audio signal of 400 Hz, –7.5 dBs simultaneously to
both L and R channels of Audio Line Input.
2) Make recording
3) Play back a recorded portion.
4) Confirm that a playback level is –7.5 ±2 dBs.
5) Confirm that a distortion factor is within 1%.
3) Play back a recorded portion.
4) Confirm that a playback level is –7.5 ±2 dBs.
5) Confirm that a distortion factor is within 1%.
4. Overall S/N Check
Purpose:
Confirm that the S/N is within the specification.
Confirm that the S/N is within the specification.
Mode
REC and PB (SP mode)
Signal
Short
Measurement point
Audio output terminal
Measurement equipment
Audio noise meter
Specified value
–67.5 dBs or less
Confirmation Method:
1) Connect both L and R channels of audio line input to the GND.
2) Start recording.
3) Play the recorded part to confirm that the noise is below –67.5
1) Connect both L and R channels of audio line input to the GND.
2) Start recording.
3) Play the recorded part to confirm that the noise is below –67.5
dBs.
2-4-2.
Normal Audio System Adjustment
• Make adjustment in the SP mode, unless otherwise specified.
Use a normal VHS cassette for an adjustment tape.
• Set AUDIO MONITOR to normal.
[Adjustment Sequence]
1. ACE Head Adjustment
2. E-E Output Level Check
3. Frequency Responce Check
4. Overall Level Characteristic and Distortion Factor
1. ACE Head Adjustment
2. E-E Output Level Check
3. Frequency Responce Check
4. Overall Level Characteristic and Distortion Factor
Check
5. Overall S/N Check
1. ACE Head Adjustment
Refer to the service manual of VHS MECHANICAL
ADJUSTMENT
ADJUSTMENT
VI
.
2. E-E Output Level Check
Purpose:
Confirm that the output level against the reference input is within
the specification.
Confirm that the output level against the reference input is within
the specification.
Mode
E-E
Signal
L, R: 400 Hz, –7.5 dBs
Measurement point
Audio output terminal
Measurement equipment
Audio level meter
Specified value
–7.5 ± 2 dBs
Confirmation Method:
1) Simultaneously input a signal of 400 Hz, –7.5 dBs to both L
1) Simultaneously input a signal of 400 Hz, –7.5 dBs to both L
and R channels of Audio Line Input.
2) Confirm that the audio output level is –7.5 ± 2 dBs.
3. Frequency Responce Check
Purpose:
Confirm that the frequency characteristic is within the specifica-
tion.
Confirm that the frequency characteristic is within the specifica-
tion.
Mode
REC and PB (SP mode)
Signal
400 Hz, –30.0 dBs
7 kHz, –30.0 dBs
7 kHz, –30.0 dBs
Measurement point
Audio output terminal
Measurement equipment
Audio level meter
Specified value
0 ± 4 dB
Tape path adjustment must have been completed.
Confirmation Method:
1) Supply a signal of 400 Hz, –30.0 dBs to both L and R chan-
1) Supply a signal of 400 Hz, –30.0 dBs to both L and R chan-
nels of Audio Line Input.
2) Connect the audio level meter to the Audio Line Output.
3) Adjust the attenuator so that the audio level meter will indi-
3) Adjust the attenuator so that the audio level meter will indi-
cate –30.0 dBs.
4) Make recording in the SP mode.
5) Set an audio line input signal to 7 kHz and make recording.
6) Playback a recorded portion, and measure output levels at 400
5) Set an audio line input signal to 7 kHz and make recording.
6) Playback a recorded portion, and measure output levels at 400
Hz and 7 kHz.
7) Confirm that the 7 kHz playback output level within a range
of the 400 Hz playback output level 0 ± 4 dB.
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