Sanyo VHR-790 User manual

FILE NO.
SERVICE MANUAL
Video Cassette Recorder
—
(VHR-790)
PAL
CONTENTS
SELF-DIAGNOSIS DiSPLAY .................................................... 2
1. DISASSEMBLY .................................................................... 5
2. ELECTRICAL ADJUSTMENT .............................................. 9
3. TEST POINTS FOR TAPE PATH ADJUSTMENT .............13
4. PARTS LIST
MECHANISM PARTS ......................................................... 14
Accessories .................................................................. 16
PACKING MATERIALS ...................................................... 16
CABINET &CHASSIS PARTS ........................................... 16
ELECTRICAL PARTS ........................................................ 17
CIRCUIT DIAGRAMS (Refer to the separate volume)
*O
VHR-790
(Product Code: 143171 54)
(New Zealand)
VHR-790
(Product Code :143171 53)
(Australia)
VHR-7671R
(Product Code :143171 68)
(Ireland)
Please see other materials with Reference
number given in table below.
Materials Model No. Reference No.
V95 I
Mechanism Mechanism MM531433
Manual V95 II
Mechanism MS531500
~‘RODucT‘AFETY‘OT’cE
The components designated by asymbol (~) in this schematic diagram designates components whose value are of special
significance to product safety. Should any component designated by asymbol need to be replaced, use only the part designated
in the parts List. Do not deviate from the resistance, wattage, and voltage ratings shown.
NOTE: 1. Parts order must contain model number, part number, and description.
2. Substitute parts may be supplied as the service parts.
3. N.S. P. :Not available as service parts.
Design and specifications are subject to change without notice.
MP4HN/NZ, A, IR3 REFERENCE No. SM531597

SELF-DIAGNOSIS DISPLAY
Mechanism Mode Display/ Head Output Drop Warning Display/ Cylinder Rotation Accumulated
Time Display
This unit displays the diagnosis contents of abnormalities and the mechanism, mode on its display panel in 2-digit numbers.
When the head playback output has dropped, the “L” sign will be blinked. Some models (listed later) will also display the cylinder
rotation accumulated time.
These display shows the outline of the problems. Use it as areference when servicing the unit.
1.
●
.
.
●
Self-Diagnosis Contentes and Mechanism Mode Display
When the STOP button on the remote control is pressed for about 10 seconds continuously, the self-diagnosis number will be
displayed on the reception channel display of the display panel and number indicating the failed mechanism mode (changed mode
when being shifted) on the tape counter “seconds” display for 10 seconds each.
During self-diagnosis display, displays other than the diagnosis number/mechanism mode number and the cylinder accumulated
rotation time display described later (some models only) will be turned off and when displays end, the normal display will be
returned automatically.
Refer to “Self-Diagnosis Contents” for the self-diagnosis numbers and the “Mechanism Mode Display Contents” for the
mechanism mode numbers.
When the “O” button on the remote control unit is pressed during display, and clearing the self-diagnosis display and mechanism
mode display.
(
Display panel n 1: n J
U _/ u I_
/4 4
\I ,
Self -Diagnosis number Mechanism mode number
(Recept”fin channel display) (Tape counter “Seconds” display)
Self-Diagnosis Contents
No. Problem Main Possible Cause Mechanism Operations and
State After Occurrence
00 There is no abnormality in the mechanism.
The cylinder motor does not rotate. ●The cylinder motor is faulty. Shifts to the STOP mode.
●The control of the cylinder motor is
01 faulty,
●The tape winds around the cylinder.
The take-up reel does not rotate. ●The take-up reel is caught. Shifts to the STOP mode.
02 ●The reel belt is faulty.
●The take-up torque has decreased.
The capstan motor does not rotate. ●The capstan motor is faulty. Shifts to the STOP mode.
03 ●The control of the capstan motor is
faulty.
The tape cannot be loaded with the ●Error in the operations of the tape Unloads, shifts to the INITIAL mode,
cassette inserted. loading mechanism. and the power goes off.
(But unloading can be performed.) ●Foreign particles in the tape load-
04 ing mechanism.
cThe tape end sensor is faulty.
●The reel brake of the tape cassette
has not been released.
Tape loading and unloading cannot ●The tape guide is caught. The power is forcibly turned off with
05 be performed with the cassette in- ●The loading motor is faulty. the mechanism at its current position.
serted. ●The control of the loading motor is
faulty.
–2-

No. Problem Main Possible Cause Mechanism Operations and
State After Occurrence
Front unloading cannot be performed ●The cassette drive mechanism is Front loads and shifts to the STOP or
when ejecting the cassette. faulty. INITIAL mode.
(Front loading can be performed.) ●The front door is caught. ●When the power switch is turned on
before eject operations: Shifts to the
06 STOP mode.
●When the power switch is turned off
before eject operations: Shifts to the
INITIAL mode and the power goes
off.
Front loading and front unloading can- ●The tape cassette is caught in the The power is forcibly turned off with
not be performed when ejecting the cassette drive mechanism. the mechanism at its current position.
cassette. ●The main cam and front rack gear of
07 the front loading mechanism have
not engaged properly.
●The gears of the front loading drive
mechanism have not engaged prop-
erly.
The mechanism becomes 1(RE- ●The mechanism mode switch con- The power is forcibly turned off with
08 VIEW) while moving from 2(IDLER), tact is faulty. the mechanism at its current position.
3(STILL), 4(BRAKE), and to 5
(STOP).
The mechanism becomes 7(INITIAL) ●The mechanism mode switch con- Carries out tape take-up operations,
09 while moving from 1(REVIEW), 2tact is faulty. shifts to the INITIAL mode, and the
(IDLER), 3(STILL), 4(BRAKE), and power goes off.
to 5(STOP).
Note: For details of mechanism operations corresponding to the mechanism positions of the self-diagnosis numbers 08 and 09 above,
refer to the separate volume on the V95 Imechanism manual. These manual reference numbers are shown in the cover
Mechanism Mode Display Contents
Mode No.
00
01
02
03
04
05
06
07
Mechanism Mode
CASSETTE OUT
STANDBY
STOP
STILL
REC-PAUSE
AUDIO DUBBING-PAUSE
FRAME ADVANCE
SLOW
Mode No.
08
09
10
11
12
13
14
15
Mechanism Mode
PLAY
REC
AUDIO DUBBING
X2 SPEED PLAY
CUE
REVIEW
FAST FORWARD
REWIND
Mode No.
16
17
18
19
99
Mechanism Mode
VIDEO INSERT
VIDEO INSERT-PAUSE
AUDIO/VIDEO INSERT
REVERSE X2 SPEED PLAY
OTHERS
2. Head Output Drop Warning Display
●When the STOP button on the remote control is pressed for 10 seconds continuously 10 seconds after play starts, “L” will be
displayed blinking at the first digit of the minutes position on the tape counter when the head output is lower than the specified
value to indicate an abnormality.
●The cause of the abnormality may be due to drop in the playback output caused by drop in the efficiency of the cassette used or
head clogging. Refer to “Head Playback Output Voltage Check” as ameans to judge the abnormality.
Display panel
L\&
Head output drop warning display
(Tape counter”1 st digit of Minutes.” position)
–3-

Head playback output voltage check
Warning
)assette Used Display Envelope Detection Output Voltage Main Cause
Envelope detec- 4V ...................................
kz+”’-o”v !%(:::::::::
When the output voltage differ-
Cassette tion output
(IC301 Pin 25 or
with normal R3032 Mark side:
playback –see Fig. 2-l-1) “v
output Switching pulse
(TP183: see Fig. normal
CH-1 CH-2
2-l-2)
Envelope detec- ~v ___________________________________ When the output voltage differ-
tion output
(IC301 Pin 25 or
R3032 Mark side:
,,L1l blinking see Fig. 2-l-1) ‘v &!Y:~Jhan ‘n~fiw:::::::
Switching pulse been performed accurately
(TP183: see Fig. CH-1 CH-2 ●One video head is clogged
Recorded 2-l-2) ●One video head has worn out
cassette
(with tabs) When the average output volt-
Envelope detec- 4V ...................................
tion output
(IC301 Pin 25 or
R3032Markside:
IL,, bllnking see Fig. 2-l-1) “v ~,:,than ~K~::;;;;;
Switching pulse
(TP183: see Fig. ●Both video heads are clogged
CH-1 CH-2
2-l-2) .Both video heads have worn
out
Envelope detec- ~v ___________________________________
tion output
(IC301 Pin 25 or
“L” blinking R3032 Mark side:
Rental see Fig. 2-l-1) ‘v klz~:$flan :$gg:d
Switching pulse
cassette (TP183: see Fig. CH-1 CH-2 ●One video head is clogged
(without tabs) 2-l-2) ●One video head has worn out
●Some rental cassettes may have extremely low video playback outputs even when both video heads are normal.
As the average output voltage of the two heads maybe less than 0.5V for some, no warning displays will be
shown.
3. Cylinder rotation accumulated time display
●Press the STOP button on the remote control for approximately 10 seconds and the cylinder rotation accumulated time excluding
the cassette out and standby operation time will be displayed on the “Hours” display in units of 100 hours. (“33” will be displayed
for 10 seconds for 3,200 to 3,299 hours.)
●To erase the cylinder rotation accumulated time display, press the RESET button on the remote control during the accumulated
time display.
II
—1 I
Cylinder rotation accumulated display (Tape counter “Hours” display)
-4–

1. DISASSEMBLY
1-1. REMOVAL OF CABINET, MECHANISM UNIT, AND MAIN BOARD
REMOVING THE CABINET PARTS (Fig. l-l-l) 1. Spread out the lock clamps (C) in the arrow direction
1.
2.
Remove the cabinet and bottom cover by removing the four slightly and remove the TM-1 PWB as shown in Fig. 1-1-2.
screws zand four screws @. 2. Remove the screw @at the chassis.
Remove the front panel by removing the locks of the clamps 3. Remove the screw@ in the chassis, the screw \@l,and the
(A) using ascrewdriver, etc. and slightly rotating the bottom holder in this order.
part in the direction of the arrow. 4. Remove the two screws @and two screws @of the
mechanism unit. The two screws @of the cassette tray can
Notes: ●Electrical adjustments for the this model can be be removed easily by pushing the tray lock lever in the
performed with only the cabinet removed. arrow direction to remove the lock as shown in the enlarge
●When replacing the bottom cover, do not tighten the view Aand by pushing the lid opener lever in the arrow
screws’~ too much. Excess tightness may damage direction to remove the lock as shown in the enlarge view
the screws taps on the chassis. B.
5. Lift up the whole mechanism unit and main board (CP-1
REMOVING THE MECHANISM MAIN UNIT AND THE PWB assembly), and as shown in Fig. 1-1-3, push the two
CP-1 PWB ASSEMBLY (Fig. 1-1-2 and l-l-3) lock clamps (D) of the chassis in the arrow direction so that
.- they can be removed from the chassis.
—After removing the cabinet parts, remove the mechanism unit
and the CP-1 PWB assembly connected as follows.
M-PF2HNmA-l
Front Panel
(&J
Fig. 1-1-1
–5–

M-PF2HN/-rA-2
Tray Lock Lever
>II Cassette Tray
wFig. 1-1-2
M-PF2HN/lA-3
TM-2 PPWB Assembly
.Chassis
Fig. 1-1-3
–6–

1-2. TEMPORARILY SEITING UP AND CONNECTING CP-1 PWB ASSEMBLY
The following is an example of how to place and connect the main board without ajig, when repairing the CP-I PWB assembly.
1. Place the mechanism unit and main board up side down as 2. Operete the unit using the buttons on TM-1 PWB or the
awhole on a flat surface with foil side of the main board remote control.
facing up.
M-PF2HNiTA-4 CP-1 PWB Assembly (Foil side)
\\
TM-2 PWB Fig. 1-1-4
1-3. INSTALLATION OF THE FRONT PANEL
When installing the front panel to the chassis after repaires and adjustments.
1. Pressing down the door opener lever of the mechanism Note: Opened cassette door position does not install the front
main unit. panel to the chassis.
2. Set the cassette door to half-opened state as shown in Fig.
1-1-5, and install the front panel to the chassis.
M-PF2HN~A-5 Jutted Dart of
Front
(Position B) Fig. 1-1-5
–7-

1-4. CIRCUIT BOARD LOCATIONS
L-MP4HNINZ, MP4HN/A, MP4HN/E3
VHR-790
3i”’T”nern A
(New Zealand) (Tuner/lF/RF Con..) ~VP-1 PWB Assembly
CP-1 PWB Assembly
VHR-790
(Australia)
“’;e’EFT- rvp-’pwBAssemb’y
TN-3 PWB ~
TB-2 PWB -
‘~.pwB>_
VHR-7671R
TN-5
CP-I PWB Assembly
CP-1 PWB Assembly
–8–

2. ELECTRICAL ADJUSTMENT
VCR PRESETTING
This VCR need three basic presetting by using the menus displayed on-screen. After all connection have been made, then follow steps
ito 3to preset the VCR.
The three presetting steps will be displayed in sequence on TV screen. The setting are entered with the remote control.
Turn on the VCR
1. Adjusting the TV receiver to the video channel: The AUTO SETUP screen will appear. When the video channel has been preset,
press the OK button on the remote control.
2. Country selection: Using the numeric button, select the country of use.
3. Language selection: When the desired language has been select, press the MENUI7W button directly before prevent auto tuning
will start.
When steps 1to 3have been finish, ready to operate the all operating mode.
2-1. SERVO CIRCUIT ADJUSTMENT
.These adjustments should be done upon completion of the tape transport adjustments.
●If the tape transport adjustments (except the tilt adjustment) are done after these adjustments, follow the procedures again in
section 2-1-3, “Switching position adj. ”
-* When acassette tape is loaded, auto-tracking will be set immediately after starting the first playback. As this will daviate the
tracking center set, be sure to press the channel buttons (+) and (–) once directly after starting playback to prevent auto-tracking
from being set.
2-1-1. TEST EQUIPMENT AND STANDARDS REQUIRED
IOscilloscope IVertical sensitivity :5 mV/DIV, external trigger I
Bandwidth :more than 10 MHz
Alignment Tape VHJ-0009 or VHJ-O023 :SP mode, monoscope, 6KHz
Blank Tape VHS-tv~e cassette ta~e
Monitor TV
2-1-2. LOCATION OF ADJUSTMENT POINTS
P12000B
I
o
3D’
TP306 ---
TP307 --- v~:ol
:,)
.-. :
1VR351
;...,,
‘..g ,,
+on
LCP-1 PWB (Foil side) Fig. 2-1-1
-9-

P66300D TP183 TP182
(SW:P) (ENV.)
VP-1 PWB Assembly Fig. 2-1-2
2-1-3. SWITCHING POSITION ADJ.
Measuring Point IMeasuring Equipment
TP101 Oscilloscope
(VIDEO OUT)
TP183 (SW-P)
Adj. Condition
PIAY (SP) mode
Alignment tape
(VHJ-0009 or
VHJ-0023)
Adj. Location IAdj. Value
\VR351 (SW-P) I6.5 H*0.5H I
1. Play back the alignment tape.
2. Set the tracking control position to the center by pressing
CHANNEL buttons (-l-) and (–) simultaneously.
3. Adjust VR351 (SW-P) so that the width of “T” becomes 6.5
H~().5 Has shown in Fig. 2-1-3.
WS-S!NP
T=6.5H tO.5H
.0.5H
N,Al,,”, ,
/
Front edge of
vetitcal sync signal
Tt
Rise RF. SW. PULSE
Fig. 2-1-3
-1o-