DOWNLOAD Sharp VC-MH815 (serv.man9) Service Manual ↓ Size: 104.21 KB | Pages: 7 in PDF or view online for FREE

Model
VC-MH815 (serv.man9)
Pages
7
Size
104.21 KB
Type
PDF
Document
Service Manual
Brand
Device
VCR / Electrical adjustment
File
vc-mh815-sm9.pdf
Date

Sharp VC-MH815 (serv.man9) Service Manual ▷ View online

28
VC-MH705HM/LM
VC-MH815HM/LM,MH85HM
VC-MH715HM,MH835HM
Figure 5-1.
5. ELECTRICAL ADJUSTMENT
Notes:
• Before the adjustment:
Electrical adjustments discussed here are often required after replacement of electronic components and mechani-
cal parts such as video heads.
Check that the mechanism and all electric components are in good working condition prior to the adjustments,
otherwise adjustments can not be completed.
• Instruments required:
Colour TV monitor
Dual-trace oscilloscope
Audio signal generator
AC milli-voltmeter
Blank video cassette tape
Alignment tape(VROCPSV)
Screwdriver for adjustment
Colour bar singnal generator
• Location of controls and test points
TP201
29
VC-MH705HM/LM
VC-MH815HM/LM,MH85HM
VC-MH715HM,MH835HM
Measuring
instrument
Mode
Cassette
Dual-trace oscilloscope
Colour TV monitor
Playback
Alignment tape
SERVO CIRCUIT ADJUSTMENT
ADJUSTMENT OF HEAD SWITCHING POINT
Measuring
instrument
Mode
Cassette
Colour TV monitor
Playback still
Self-recorded tape (SP/LP,EP mode)
(See Note below 
1
)
Control
Tracking control buttons (+) or (
-
)
Specification
No vertical jitter of picture
ADJUSTMENT OF PAL SYSTEM FV (False
Vertical Sync) OF STILL PICTURE
Test point
Pin(2) of TP201 (H.SW.P.) to CH-
1, VIDEO OUT jack to CH-2
(CH-1 trigger slope switch at (+),
Internal trigger at CH-1 side.)
Specification
6.5 
±
 0.5H (lines)
1. Remove the front panel and play the alignment tape.
2. Get TP801 short circuited or press press "TEST"key(47H)
at Universal remote control to call the test mode.
(LCD will blinking as tracking goes to center)
3. Press "PLAY" key.
Auto PG Mode will be ON and playback mark " 
>
  "
blinking.
4. Press "STOP" key
>
 " blinking stops and auto adjustment finished.
5. Check that V-Sync is 6.5
±
0.5H and the waveform is as
shown in Figure 5-2.
Note:
For manual PG Adjustment,press FF or REW key at
the Test Mode to set the tracking in center.
6.5
±
0.5H
V: 2V/div
CH-1
Head Switching Pulse
CH-2
Video signal
Figure 5-2.
Head
Tape
2
CBZF
2LP
BBZG
4
CBZF
4HiFi
CBZF
1. Play a self-recorded tape.
2. Press the PAUSE/STILL button to freeze the picture.
3. Adjust (+) or (
-
) TRACKING buttons on the remote
control so that the vertical jitter of the picture is mini-
mized.
Note:
1
Self-recorded tape is a cassette which program was
recorded by the unit being adjusted.
2
The FV goes back to the it's initial state when the unit
is put into the system controller reset mode due to
power failure,etc.
In this case, preset the FV once again.
Y/C CIRCUIT ADJUSTMENT
CHECKING OF VIDEO E-E LEVEL
Measuring
instrument
Mode
Input signal
Oscilloscope
E-E or Record
EIA colour bar (1.0Vp-p)
Test point
VIDEO OUT jack
Specification
1.0 
±
 0.2 Vp-p
1. Connect a 75 ohm terminating resistor to the VIDEO
OUT jack and connect an oscilloscope across this
termi-nating resistor.
(See Note below.)
2. Feed a colour bar signal to the VIDEO IN jack.
3. Make sure that the E-E signal amplitude is 1.0Vp-p as
shown in Figure 5-3.
Note:
If the 75 ohm terminating resistor is missing, the signal
amplitude will be doubled.
1.0 Vp-p
Figure 5-3.
30
VC-MH705HM/LM
VC-MH815HM/LM,MH85HM
VC-MH715HM,MH835HM
1. Be sure that E-E level has been correctly specificed.
2. Connect a 75 ohm terminating resistor to the VIDEO
OUT jack and connect an oscilloscope across this
terminating resistor.(See Note below  1)
3. Play a self-recorded tape.
4. Make sure that the output signal amplitude is 1.0Vp-p
as shown in Figure 5-4.
Note:
1
If the 75 ohm terminating resistor is missing, the signal
amplitude will be doubled.
2
Self-recorded tape is a tape which program was re-
corded by the unit being adjusted.
1.0 Vp-p
Figure 5-4.
CHECKING OF PLAYBACK LEVEL
Measuring
Oscilloscope
instrument
Mode
Record/Playback
Cassette
Self-recorded tape
(See Note below 2)
Specification
1.0
±
0.2Vp-p
1. Connect an AC milli-voltmeter to the AUDIO OUT jack.
2. Feed the audio signal shown in table to the AUDIO IN
jack.
3. Put the unit in E-E or recording mode.
4. Make sure that the output level is value shown in table.
AUDIO CIRCUIT ADJUSTMENT
CHECKING OF E-E LEVEL
Measuring
AC milli-voltmeter
instrument
Mode
E-E/Record
Input signal
1kHz, –3.8 dBs
Test point
AUDIO OUT jack
Specification
–3.8 
±
 2dBs
1. Connect an AC milli-voltmeter to the AUDIO OUT jack.
2. Feed the audio signal shown in table to the AUDIO IN
jack.
3. Make the self-recording and playback of the signal.
4. Make sure that the output level is value shown in table.
CHECKING OF AUDIO RECORD LEVEL
Measuring
AC milli-voltmeter
instrument
Mode
Record/playback
Input signal
1kHz, –8.0 dBs
Test point
AUDIO OUT jack
Specification
–8.0 
±
 3dBs
CHECKING OF ERASE VOLTAGE AND OS-
CILLATION FREQUENCY
Measuring
Oscilloscope
instrument
Mode
Record
Test point
Full erase head
Control
T601
Specification
70 
±
 5kHz, 40Vp-p or greater
31
VC-MH705HM/LM
VC-MH815HM/LM,MH85HM
VC-MH715HM,MH835HM
Observe the video output using the osiloscope and con-
firm as the above diagram
*
V:200mV/div
H:20
µ
 sec/div
Measuring
instrument
Mode
Cassette
Spectrum
Analyzer
Record
Self-recorded tape
Test point
YC CHIP Pin98
Specification
3.8MHz
±
50KHz
ADJUSTMENT OF FM Carrier Confirmation
VIDEO
PAL Colour Bar(1Vp-p)
Measuring
instrument
Mode
Cassette
Osiloscope
Record
Self-recorded tape
(SP/EP mode)(See Note below)
Test point
VIDEO OUT 21PIN or RCA Port
(75
 Terminal)
Specification
1.0
±
0.2Vp-p
Y/C CIRCUIT ADJUSTMENT
ADJUSTMENT OF EE Level Confirmation
VIDEO
PAL Colour Bar(1Vp-p)
Measuring
instrument
Mode
Cassette
Spectrum
Analyzer
Record
Self-recorded tape
Test point
YC CHIP Pin98
Specification
4.8MHz
±
100KHz
ADJUSTMENT OF Deviation Confirmation
VIDEO
Colour Bar(1Vp-p)
Measuring
instrument
Mode
Cassette
Osiloscope
Self-recorded/Playback tape
Test point
YC CHIP Pin98
Specification
about300mVp-p
ADJUSTMENT OF REC Current Confirma-
tion
VIDEO
Colour Bar(1Vp-p)
1.0Vp-p
Record
<Diagram A>
Confirm the Sink chip is as the
left diagram <Diagram A>.
Sink Chip
3.80
4.80MHz
A
f
<Deviation>
Confirm the white peak frequency
follow the standard value.
(the deviation between shinkchip and
f white peak is 1MHz
±
100KHz)
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  • Here you can View online or download the Service Manual for the Sharp VC-MH815 (serv.man9) in PDF for free, which will help you to disassemble, recover, fix and repair Sharp VC-MH815 (serv.man9) VCR. Information contained in Sharp VC-MH815 (serv.man9) Service Manual (repair manual) includes:
  • Disassembly, troubleshooting, maintenance, adjustment, installation and setup instructions.
  • Schematics, Circuit, Wiring and Block diagrams.
  • Printed wiring boards (PWB) and printed circuit boards (PCB).
  • Exploded View and Parts List.