Panasonic NV-MV20GC User manual

ORDERNO. MAVR0304004C8
VideoCassette Recorder
NV-MV20GC/ NV-MV20GCS/ NV-MV20GM/ NV-MV20GL / NV
-MV20EE / NV-MV20GCU / NV-MV20GCF / NV-MV20GH
R4-MECHANISM
SPECIFICATIONS
2003 Matsushita ElectricIndustrial Co., Ltd. All rights reserved.

Unauthorizedcopying and distribution isaviolation oflaw.
1. INTRODUCTION
1.1. INTRODUCTION
This service manual contains technical information whichwill allowservice personnel to
understand and service this model.
Ifthe circuitis changedormodified, this information will be followedbysupplementaryservice
manual to be filedwith original service manual.
Note:
1. Adjustmentprocedures, DisassemblyProcedures and Assembly
Procedures for MechanismChassisareseparate volumefrom this
service manual.
Please refertotheservice manual for R4-MechanismChassis.
(OrderNo. VRD0202010C8)
2. TheModel No. isindicatedon theSchematicDiagramand Circuit
Board Diagramsas follows.
Model No. Indication Mark
NV-MV20GC/GCS/GM (A)
NV-MV20GL (B)
NV-MV20EE (C)
NV-MV20GCU/GCF (D)
NV-MV20GH (E)
1.2. ABOUTLEADFREE SOLDER(PbF)
Distinction of PbF PCB:
PCBs (manufactured) using leadfree solderwill have a PbF stamp on the PCB.
Caution:
-Pbfree solderhas ahighermelting pointthanstandard solder,
Typicallythemelting pointis50-70°F(30-40°C) higher. Please use

ahigh temperaturesoldering iron. Incase ofsoldering iron with
temperaturecontrol,please set itto700±20°F(370±10°C)
-Pbfree solderwill tend tosplashwhenheatedtoo high (about
1100°F/600°C).
Whensoldering orunsoldering, please completelyremove all of the solderon the pins orsolder
area, and be sure to heatthe soldering points with the Pbfree solderuntil itmelts enough.
2. GENERALDESCRIPTIONS
2.1. SERVICE CAUTION-1
Whenthe MicroprocessorIC6001 and/orBack-up batteryB7751 are replaced, readthe following
procedure carefullyand proceedit.
[REASONS]
There is a RAMinthe IC6001, whichis backing up:
1. ProgrammeNavigation Data [See NOTE1]
2. TV Tuning Data
3. PG ShifterAdjustmentData
4. Option Setting Data
WhenIC6001 are replaced, all above listeddata become not available.
These data is backedup byusing the powersource of:
*AC Connected: AC Powersource
*AC Disconnected: Back-up Battery(B7751)& Back-up Capacitor(C7752)
[NOTE1]
As foryourreference, without inserting a tape into a VCR, you canconfirmthatthe NAVI data
thatis back up with IC6001 as showninthe following steps.
1. Indicate the"NAVI"markon theFrontInformation Panel. (Press
theMenu button and select theoption, thenset the"NAVI"toON
mode.)
2. Turn on theService Modeand press the"NAVI"button on the
Remote Controllerinmorethan5seconds. The"NAVI"data list is
displayedon theMonitor. (Press the"MENU"button on the
Remote Controllerfor cancellation.)
Although storedNAVI data canbe confirmedon the monitor, there is no wayto transferthe
NAVI data to IC6001whichis newlymounted.
2.1.1. REPLACINGPROCEDURE[IC6001]

[1.PREPARATION]
Before replacing IC6001:
1. Take note that storedTV broadcast channels. (Because, its user
maystoreTV broadcasts bymanuallyotherthan"AutoTuning"
operation and itisalsoerased.)
NOTE:
During servicing, do not make a shortcircuitbetweenIC6001-pin37 (5V)with otherline/
Components otherwise IC6001 maybe broken.
CAUTION:
*Whenreplacing theB7751, besuretoread/followthe"HOWTO
REPLACE THE LITHIUM BATTERY"section.
[2.REPLACINGPROCEDUREIN STEPS]
STEP1.PREPARATION
1. Disconnect theACplug beforeremoving theC.B.A. with
Mechanismunitbyreferring totheDisassemblyprocedure.
STEP2.REPLACETHEIC6001
1. Replace theIC6001. (Donotmake ashortcircuitbetweenIC6001-
pin37 and otherpins/ components.)
STEP3.RESETTHEIC6001 ATONCE
1. Connect theACplug.
2. Connect ajumperwirebetweenTL7510 (RESET)and TL7509
(GND) for asecond toreset theMicroprocessor IC6001.

Note:
Since the resistance atpin2 as well as pin3 of IC6001 decides the model distinction data, there
is no needto setup the Model code, whichis necessaryinthe previous models.
STEP4.LINE-IN SETTING& ACTIVATEPLUG-IN A.T.P.
(FOR OTHER THAN NV-MV20GL)
1. Press theChannel up and downkeyssimultaneouslyfor more
than3seconds, underthecondition oftheno tapeisintheunit.
2. Confirm that "AV"canbedisplayedon theFIP bypressing theCH
UP and CH DOWNbuttons.
NOTE:
If"DIRECTREC"on the OPTION setting screenis setto [ON], the input signal is fixedto "AV",
and the Channel up and downkeys are not effective.
3. Disconnect theACplug for fewsecondsand connect itagain,
and press POWERbutton for turning thepowertoon from off to
carryoutthe"Plug inAutoTunerPreset".
4. Since otherthanthechannelsthat canbestoredby"Auto
Tuning" operation arenotavailableyet, preset manuallyby
consulting thenote ofits availableTV channelsofwhichyou took
before.
NOTE:
The Factoryshipping condition of OSD setting is not restoredbyabove operation.
5. ChangetheOSDsetting totheFactoryshipping condition if
necessary, byreferring toOption Setting on theOperating
Instructionsas showninthefollowing chart.

STEP5.COMPATIBILITYADJUSTMENT
Referto the Electrical Adjustment Procedures.
2.2. CAUTIONFORACMAINS LEAD(NV-MV20GH)
2.3. HOWTO REPLACE THE LITHIUM BATTERY
2.3.1. GENERALDESCRIPTION
There is a RAMinthe IC6001, whichis backing up the following data byusing the powersource
of B7751 (Back-up Battery)and C7752 (Back-up Capacitor:Back-up time is approximately30
minutes).
1. ProgrammeNavigation Data
2. TV Tuning Data
3. PG ShifterAdjustmentData
4. Option Setting Data
2.3.2. REPLACEMENT PROCEDURE
NOTE:
This work shouldbe finishedwithin30 minutes sothatthe RAMdata wouldnot be lostas
running out of current from the Back-up CapacitorC7752.
1. RemovetheTop Panel and MechanismunitwithMainC.B.Aby
referring totheDisassembling Procedure.
2. UnsoldertheLithium Battery:B7751 and thenreplace itwitha
newone(See Fig. B1 ).
Fig. B1

NOTE:
The lithium batteryis a critical component (ManufacturedbyPanasonic.)
Itmustneverbe subjectedto excessive heatordischarge.
Itmusttherefore onlybe fittedinequipment designedspecificallyforits use.
Replacement batteries mustbe of the same type and manufacture.
Theymustbe fittedinthe same mannerand location as the original battery, with the correct
polaritycontacts observed.
Donot attempt to re-charge the batteryorre-use itforanyotherpurpose.
Itshouldbe disposedof inwaste products destinedforburial ratherthanincineration.
2.4. SERVICE CAUTION-2
2.4.1. CAUTIONFORAUTOTUNING

PROCEDURE
Auto Tuning will startbythe following procedure.
1. Connect theDIN-RFCable.
2. Connect theACMainsLead.
3. Turn on theVCR.
AutoTuning will start.
AutoTuning searchfor TV stationsfrom VHS minimum toUHF
maximum and memorizes everytunedprogramposition. Other
programpositionsareskipped.
AutoTuning takes fiveor moreminutes tocomplete its search.
DonottouchtheVCR during AutoTuning.
AutoTuning will stop halfway, iftheVCR isoperatedor theaerial
leadand/or themainsleadaredisconnected.
Incase theVCR stoppedduring AutoTuning, theVCR has tobe
reset and restarted. See thefollowing item2.
NOTE:
1. IftheVCR isturnedon withtheantennanotconnected, all
channelsareskipped. Therefore, firmlyconnect theantennaand
thenturn theVCR off and on againtoexecute Autotuning.
2. WhenAutoTuning iscanceledhalfway, AutoTuning isnot
execute eveniftheVCR isturnedoff and thenturnedon again,
Inthiscase, AutoTuning has toberestartedbythefollowing
procedures.
A. Press EJECTand removetheVideocassette.
B. KeepUP and DOWNon theVCR pressedsimultaneouslyfor 3
secondsor moreduring theVCR on.
Thechannel displayedon theVCR displaydisappearsfor
momentthenchanges to2.
C. Turn off theVCR and thenturn iton. AutoTuning commences.
3. Ifyou turn theVCR off during AutoTuning, AutoTuning will stop
halfway.
TheVCR shouldbereset and restartedbytheitem2inorderto
execute AutoTuning.

4. IftheVCR starts playback during AutoTuning, AutoTuning will
stop halfway.
TheVCR shouldbereset and restartedbytheitem2inorderto
execute AutoTuning.
5. Tocancel AutoTuning Mid-operation, press POWERDuring Auto
Tuning (TheVCR isturnedoff).
6. WhentheVCR ismovedtotheotherarea or country, TV
broadcasts shouldbestoredagain.
2.4.2. CHECKINGOFMAINC.B.A.
Whenservicing the MAIN C.B.A., take out the MAIN C.B.A. and mechanismfrom the frame. Turn
the MAIN C.B.A. overas shownin Fig. S1 .
Fig. S1
2.4.3. REMOVALOFCASSETTETAPE
Whenthe cassette tape couldnot be uninstalledfrom anelectrical malfunction, There are 2
ways to remove a cassette tape.
1. Removal bycompulsoryunloading.
A. Press FF and EJECTbutton simultaneouslyfor morethan3
secondsand set theService Modeto7.
B. Press STOP button inordertounloadthemechanism. (Pay
attention totapeslack)
Service ModeIndication:
7** ** (STOP)70L** (EJECT)
2. Removal bymanual operation byrotating theLoading Motor with
thebatteries.
A. Disconnect theACplug, and removetheTop Panel and the

FrontPanel byreferring totheDisassemblyProcedures.
B. Connect three batteries (1.5V spec.)totheLoading Motor in
series for supplying 4.5V torotate theLoading Motor as shown
in Fig. S2 . Fig. S2
C. Stop unloading just beforeunloading wouldbecompletedas
shownin Fig. S3 . Fig. S3
D. Thenthetapebecomes slack as shownin Fig. S4 .
Fig. S4

E. Rotate theS-Reel byasmall minusscrewdriver(Fig. S5 )to
removetheslack tapeas shownin Fig. S6 .
Fig. S5
Fig. S6
F. Thenunloadagaintoremovethecassette tapeas shownin
Fig. S7 . Fig. S7

3. Removal bymanual operationsafteruninstalling themechanism,
refertotheDISASSEMBLY METHODofitem3.1..
A. Disconnect theACplug, and removetheTop Panel, Front
Panel and theMechanismbyreferring totheDisassembly
Procedures.
B. RemovetheScrew(S1) and removetheLoading Motor bothas
shownin Fig. S8 . Fig. S8
C. Rotate theMainCamGearcounter-clockwise (Fig. S9 )until
just beforetheunloading wouldbecompletedas shownin Fig.
S3 .
D. Rotate theCapstanMotor clockwise (Fig. S9 )toremovethe
slack tapeas shownin Fig. S6 .
Fig. S9

E. Rotate theMainCamGearcounter-clockwise again(Fig. S9 )to
removethecassette-tapeas shownin Fig. S7 .
F. Set thePosition SwitchtoEJECTPOSITIONcertainlyas shown
in Fig. S10 . Fig. S10
G. Install theLoading Motor and tightenscrew(S1) as shownin
Fig. S8 .
2.4.4. CYLINDERUNIT REPLACEMENT
NOTE:
Replacing onlyUpperCylinderunitof R4 Mechanismcannot be performed, as securing of RT
gapis impossible out of factory, please replace the cylinderbywhole CylinderUnit. The
CompatibilityAdjustment shouldbe performedafterreplacement ofthe DD CylinderUnit.
1. RemovetheMechanismUnitfrom MainC.B.A./Chassisby
referring to"DisassemblyProcedure".

2. Unlock 2locking tabson asidetorelease theCylinderFlexible
Card as shownin Fig. S11 .
CAUTION:
HandletheCylinderFlexibleCard withcare. Whenitdamaged,
you shouldreplace itwithanewCylinderUnit.
3. RemovearedScrew(S2) and 2goldScrews(S3) toremovethe
CylinderUnitshownin Fig. S11 .
Fig. S11
NOTE:
Whenreassembling, performthe steps inthe reverse order, and performthe COMPATIBILITY
ADJUSTMENTcertainlyafterCYLINDER UNITREPLACEMENT.
2.4.5. ATTENTIONFORREPLACINGTHEDD CYLINDER
Whenreplace the DD CylinderUnit, keepnextprocedure.
1. Putthegloves on your hands.

2. Turn theDD CylinderUnitover.
Fig. S12
3. InserttheFlexiblecard intotheFPCHOLDER.
Fig. S13
4. HooktheFlexiblecard totheFPCHOLDER.
Fig. S14
5. InserttheFPCHOLDERtotheDD CylinderUnit.
Fig. S15
6. The"COMPATIBILITY ADJUSTMENT"shouldbeperformedafter

thereplacementoftheDD CylinderUnit.
NOTE:
Incase thatyou have insertedthe FPC HOLDER to the DD CylinderUnitbefore inserting the
Flexible cardinto the FPC HOLDER. Pushing stopperportion of the FPC HOLDER with a small
minus screwdriverand soon, remove the FPC HOLDER while payingattention fornot to
scratchthe DD Cylinderand not to break the HeadChipas shownbelow.
Fig. S16
2.4.6. FLAT CARD CABLEINSTALLATION
Wheninstalling the FlatCardCable on the connector, install the FlatCardCable with the cable
contacts facing the connectorcontacts.
Fig. S17
2.5. SELF-DIAGNOSIS &SERVICE INFORMATIONDISPLAY
Referto the Service Manual forR4 MechanismChassis.
(OrderNo.:VRD0202010C8).
2.6. INTRODUCTIONOFVIDEO HEADCLEANING CASSETTE /
(POLISHING TYPE)
1. Wearepleasedtointroduce PanasonicVideoHeadCleaning
Cassette, VFK0923FT[for service purposes] and VFK0923FSE [

for end users] for all VHS/S-VHS VCP and VCR.
2. These cleaning cassettes areexclusiveremoving thehard and
stickyclogging on videoheads.
3. These improvetheefficiencyofvideoheadcleaning service and
shortening cleaning timefor end users.
VFK0923FT
(ForService usage)
Type of Cassette Full VHSCassette
Cleaning Time 10 Seconds/Time
Tape Length 20 m
Usabilityina Path 180 Times
VFK0823FSE
(Forend users)
Type of Cassette Full VHSCassette
Cleaning Time 10 Seconds/Time
Tape Length 3.34 m
Usabilityina Path 30 Times

VFK0823FSE
(Forend users)
Note:
Thetapematerial itselfisthesameinbothtypes.
3. ADJUSTMENTPROCEDURES
3.1. DISASSEMBLY METHOD
3.1.1. DISASSEMBLYFLOWCHART
This flowchartindicates disassemblysteps of the cabinetparts and the circuitboards inorder
to find the necessaryitems forservicing.
Whenreassembling, performthe steps inthe reverse order.
Fig. D1

3.1.2. DETAILOFDISASSEMBLYMETHOD
1. REMOVALOFTHE TOP PANEL
Remove 2 Screws (A)
Remove 2 Screws (B)
Fig.D2

2. REMOVALOFTHE BACK PANEL
Remove 2 Screws (C)
Remove Screw(D)
Fig. D3
3. REMOVALOFTHE FRONTPANELUNIT
Unlock 7 Tabs (E)