Panasonic Omnivision VHS PV-C2780 User manual

ORDERNO. MKE0003103C1
B6
Combination VCR
PV-C2780 / PV-C2780-K
SPECIFICATIONS
2000 Matsushita-Kotobuki Electronics Industries LTD. All rights
reserved. Unauthorized copying and distribution isaviolation of
law.
1. SAFETY PRECAUTIONS
1

GENERALGUIDELINES
1. IMPORTANTSAFETY NOTICE
There are special components used inthisequipment which are
important for safety. These parts are marked by inthe Schematic
Diagrams, CircuitBoardLayout, Exploded Viewsand Replacement
Parts List. Itisessential that these critical parts shouldbe
replaced with manufacturer's specified parts to prevent X-
RADIATION, shock, fire, or other hazards. Donot modifythe
original design withoutpermission of manufacturer.
2. AnIsolation Transformer shouldalwaysbe used during the
servicing of Combination VCR whose chassisisnot isolated from
the AC power line. Use atransformer of adequate power rating as
thisprotects thetechnician from accidents resulting inpersonal
injuryfrom electrical shocks. Itwill also protect Combination VCR
from being damaged byaccidental shorting that mayoccur during
servicing.
3. When servicing, observe the original lead dress, especiallythe
lead dress inthe high voltage circuits. Ifashort circuitisfound,
replace all parts which have been overheated or damaged bythe
short circuit.
4. After servicing, see to itthat all the protective devices such as
insulation barriers, insulation papers, shield, and isolation R-C
combinations are properlyinstalled.
5. Before turning the receiver on, measure the resistance between B+
line and chassisground. Connect (-) side of an ohmmeter to the B
+ lines, and (+)side to chassisground. Each lineshouldhave
more resistance than specified, as follows:
B+ Line
Minimum Resistance
125 V
1k (Coldchassisground)
27 V
180 (Coldchassisground)
17 V
2

110 (Coldchassisground)
6. When the TV set isnot used for along period of time, unplug the
power cord from the AC outlet.
7. Potentials, as high as 32.0kV are present when thisTV set isin
operation. Operation of the TV set without the rear cover involves
the danger of ashock hazard from the TV set power supply.
Servicing shouldnot be attempted byanyone who isnot
thoroughlyfamiliar with the precautions necessarywhen working
on high voltage equipment. Alwaysdischarge the anode of the
picture tube to the CRTground of receiver before handling the
tube.
8. After servicing make the following leakage current checks to
prevent the customer from being exposed to shock hazards.
LEAKAGE CURRENTCOLD CHECK
1. Unplug the AC cord and connect ajumper between the two
prongs on the plug.
2. For physicallyoperated power switches, turn power on. Otherwise
skipstep 2.
3. Measure the resistance value, with an ohmmeter, between the
jumpered AC plug and each exposed metalliccabinet part on the
receiver, such as screwheads, connectors, etc. When the exposed
metallicpart hasa return path to the chassis, the reading should
be between 1M and 12 M . When the exposed metal does not
have areturn path to the chassis, the reading must be infinity.
LEAKAGE CURRENTHOTCHECK
1. Plug the AC cord directlyinto the AC outlet.
Donot use aisolation transformer for thischeck.
2. Connect a1.5k , 10 Wresistor, inparallel with a0.15 F
capacitor, between each exposed metallicpart on the set and a
good earth ground , as showninFigure 1.
3. Use an AC voltmeter, with 1k /Vor more sensitivity, to measure
the potential across the resistor.
4. Check each exposed metallicpart, and measure the voltage at
each point.
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5. Reverse the AC plug inthe AC outlet and repeat each of the above
measurements.
6. The potential at anypoint shouldnot exceed 0.75 VRMS.
Aleakage current tester (Simpson Model 229 equivalent) maybe
used to make the hot checks. Leakage current must not exceed 1/
2mA. Incase ameasurement isoutside of the limits specified,
there isapossibilityof shock hazard,and the receiver shouldbe
repaired and rechecked before itisreturned to the customer.
Figure 1
2. X-RADIATION
WARNING :
1. The potential source of X-Radiation inTV sets isthe High Voltage
section and the picture tube.
2. When using apicture tube test fixture for service, ensure that the
fixture iscapableof handling 32.0kV without causing X-Radiation.
NOTE :
Itisimportant to use an accurate periodicallycalibrated high
voltage meter.
1. Reduce the brightness to minimum.
2. Set the SERVICEswitch to SERVICE.
3. Measure the High Voltage. The meter reading shouldindicate 30.0
kV±2.5kV.
Ifthe meter indication isout of tolerance, immediate service and
correction isrequired to prevent the possibilityof premature
component failure.
4. To prevent an X-Radiation possibly, itisessential to use the
specified picture tube.
4

HORIZONTALOSCILLATOR DISABLE CIRCUITTESTSERVICE WARNING :
The test must be made as a final check before set is returnedtothe customer.
CONFIRMATION OFX-RAY MOVEMENT
1. Turn off TV set.
2. Connect the circuitbelow between TP1209 and TP1208.
Figure 2
3. Turn on DC Power, and then turn on the set. Confirm that the
picture ison the screen properly.
4. Confirm that the picture goes out of horizontal sync whilegetting
downthe voltage to DC Power.
5. Ifthisdoes not occur even when getting downthe voltage of DC
Power to 0V, itmeans that X-rayprotect circuitisnot operating.
Further confirmation and repairisrequired.
REPAIR PROCEDURES OFHORIZONTALOSCILLATOR DISABLE CIRCUIT
1. Connect aDC voltmeter between capacitor C513 (+)on the Main
circuitboard and chassisground.
2. Ifapproximately+21.5Visnot present at that point when 120 VAC
isapplied, find the cause. Check R503, R5505, C5507, C513 and
D503.
3. Carefullycheck above specified parts and related circuits and
parts. When the circuitisrepaired, trythe horizontal oscillator
disablecircuittest again.
CIRCUITEXPLANATION
HORIZONTALOSCILLATOR DISABLE CIRCUIT
The positive DC voltage, suppliedfromthe D503 cathode formonitoring high voltage, is applied
tothe IC5301 Pin11 through R503 and R5504. Undernormal conditions, the voltage at IC5301
Pin11 is less thanapprox 6 V. If the highvoltage at Flyback TrPin5 exceeds the specified
voltage, the positive DC voltage whichis suppliedfromthe D503 cathode alsoincreases. The
increasedvoltage is appliedtoIC5301 Pin11 through R503 and R5504. Due tothe increased
voltage at IC5301Pin11, the horizontal oscillatorfrequencyincreases, the picture goes out of
horizontal sync, the beamcurrent decreases and the picture becomes dark inordertokeepX-
radiation underspecification.
Figure 3
5

3. PREVENTION OF ELECTROSTATIC DISCHARGE
(ESD) TO ELECTROSTATICALLY SENSITIVE (ES)
DEVICES
Some semiconductor(solidstate) devices canbe damagedeasilybystatic electricity. Such
components commonlyare calledElectrostaticallySensitive (ES) Devices. Examples of typical
ES devices are integratedcircuits and somefield-effect transistors are semiconductor"chip"
components. The following techniques shouldbe usedtohelpreduce the incidence of
component damage causedbyelectrostatic discharge (ESD).
1. Immediatelybefore handling anysemiconductor component or
semiconductor-equipped assembly, drainoff anyESDon your
bodytouching aknownearth ground. Alternatively, obtainand
weara commerciallyavailabledischarging ESDwrist strap, which
shouldbe removed for potential shock reasons prior to applying
power to the unitunder test.
2. After removing an electrical assemblyequipped with ES devices,
place the assemblyon aconductive surface such as aluminum
foil, to prevent electrostaticcharge buildup or exposure of the
assembly.
3. Use onlyagrounded-tipsoldering iron to solder or unsolder ES
devices.
4. Use onlyan antistaticsolder removal device. Some solder
removal devices not classified as "antistatic(ESDprotected)" can
generate electrical charge sufficient to damage ES devices.
5. Donot use freon-propelled chemicals. These can generate
electrical charges sufficient to damage ES devices.
6. Donot remove areplacement ES device from its protective
package until immediatelybefore you are readyto install it. (Most
replacement ES devices are packaged with leads electrically
shorted together byconductive foam, aluminum foil or comparable
conductive material).
7. Immediatelybefore removing the protective material from the
6

leads of areplacement ES device, touch the protective material to
the chassisor circuitassemblyinto which the device will be
installed.
CAUTION:
Besure no power isapplied to the chassisor circuit, and observe
all other safetyprecautions.
8. Minimize bodilymotions when handling unpackaged replacement
ES devices. (Otherwise harmless motion such as the brushing
together of your clothes fabricor the lifting of your foot from a
carpeted floor cangenerate staticelectricity(ESD)sufficient to
damage an ES device).
"NOTE toCATV systeminstaller:
This reminderis providedtocall the CATV systeminstaller's attention toArticle 820-40 of the
NEC that provides guidelines forpropergrounding and, inparticular, specifies that the cable
ground shall be connectedtothe grounding systemof the building, as close tothe point of cable
entryas practical."
4. OPERATION GUIDE
5. SERVICE NOTES (PLEASE READ)
5.1. SERVICENOTES
5.1.1. SIMPLIFIED FAULT FINDING DATA
SimplifiedSelf-Diagnostic Systemfacilitates finding the cause of the fault. A 4 digit forfault
code and communication forI2C bus code will be displayedon TV screen.
The SimplifiedFault finding data is storedinthe MemoryIC (IC6004). This data is clearedafterit
is displayed, and thenthe POWER button is pressedback on.
1. With power turned off, press FF and REW buttons on unit
together for over 3seconds. Fig. 1-1
2. TV power goes on and the unitgoes into service mode.
4digitfor faultcode and communication for I2Cbus code will be
displayed. Fig. 1-2
7

Fig. 1-3
Fig. 1-4
8

Fig. 1-5
3. Press anyoperation button except for POWERon either the unit,
or the remote to detect that akeyhas been pressed.
The 1st digitchanges to "0" onlywhen keyisdetected.
Fig. 1-6
9

Note:
When 1to 4listed inLock code occurs, the VCR stops and all VCR
function buttons except for power become non-operational.
5.1.2. SERVICE POSITION
5.1.2.1. Service Position
CAUTION:
HOTCIRCUIT(Primarycircuit) exists on the TV/VCR MainC.B.A.
and the TV Power C.B.A. Use extreme care to prevent accidental
shock when servicing.
5.1.2.1.1. Service Position (1)
Fig. 2-1
5.1.2.1.2. Service Position (2)
Fig. 2-2
10

Note:
1. When recording inService Position (2), short the S-Tab SW. Pins
on foil side of TV/VCR MainC.B.A. to turn thisSW. on.
Fig. 2-3
2. When disassembling/assembling, refer to "CABINET SECTION"in
DISASSEMBLY/ASSEMBLY PROCEDURES.
5.1.3. HOTCIRCUIT
Primarycircuit exists on the TV/VCR MainC.B.A. and the TV PowerC.B.A.
This circuit is identifiedas " HOT" on the C.B.A. and inthe Service Manual. Use extreme care to
prevent accidental shock whenservicing.
5.1.4. SERVICE MODE
Inordertoinhibit detection of the Supply& Takeup PhotoTransistors, Reel Sensor, and Cylinder
Lock, place a jumperbetweenTP6001 and GND.
Inthis mode, Mechanismmovement canbe confirmed. Whenremoving Cassette UpAss'y, it
canbe confirmedwithout a cassette.
To release fromthis mode, remove the jumperbetweenTP6001 and GND.
11

5.1.5. CAUTION FOR INSTALLATION OFVCR UNIT
CAUTION:
OpenerLevermaybe damagedwhenVCR Unit is installed, withCassette Door-Lidand Opener
Leverof Cassette UpAss'yset incorrectly.
Install the VCR Unit as follows:
1. Swing the Cassette Door-Lidall the wayopen until the Cassette
Door tab clears the Opener Lever.
2. Make sure that all guide tabs are aligned properly. Then, press the
VCR Unitstraight in.
Fig. 3
5.1.6. HOW TO INITIALIZE MEMORY IC
Afterthe MemoryIC (IC6004) orTV/VCR MainC.B.A. is replaced, be sure toset the Default value
toMemoryIC as shownin"MemoryIC Reference Table" below.
1. Press and holdSTOP, PLAY, and VOLDOWNbuttons on the unit
together over 5seconds with no cassette inserted.
The adjustment overlaywill appear to Enter EVRAdjustment
mode. Fig. 4-1
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2. Set the Defaultvalue of all Control functions using aremote
control as shownin"MemoryICReference Table."
Note:
For Selecting Control functions and setting Defaultvalue, refer to "
HOW TO ENTER EVR ADJUSTMENT MODE"and "HOW TO
ENTEREVR PG SHIFTER ADJUSTMENT MODE"inELECTRICAL
ADJUSTMENTprocedures. Fig. 4-2
3. Press and holdSTOP, PLAY, and VOLDOWNbuttons on the unit
together over 5seconds againor press the POWERbutton OFF to
release EVRAdjustment Mode.
The Defaultvalue will be written to MemoryIC(IC6004).
4. Perform all EVRAdjustments. (Refer to "EVR (Electronic Variable
Register) ADJUSTMENT WITH THE REMOTE CONTROL"in
ELECTRICALADJUSTMENTprocedures.)
13

5.1.7. METHOD FOR LOADING/UNLOADING OFMECHANISM
5.1.7.1. (Manual Method)
Turnthe Loading Gearclockwise (forloading) orcounterclockwise (forunloading) using
needlenose pliers etc.
Note:
Donot use thismethod ifMechanism isjammed or locked.
Fig. 5-1
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5.1.7.2. (Electrical Method)
Apply+10.0 V DC PowerSupplytothe Loading Motorterminals.
Loading
DC+ toPortion "a," DC - toPortion "b"
Unloading
DC - toPortion "a," DC+ toPortion "b"
CAUTION:
Before applying DC Power Supply, be sure to disconnect the Motor
Leads from the Connector P2503.
Otherwise, the Loading Motor Drive IC(IC2501) maybe damaged.
Fig. 5-2
Whenloading without a cassette, pushPortion "a" on the HolderUnit of Cassette UpAss'yso
that the Leverclearthe First Taband Second Tab.
Fig. 5-3
15

5.1.8. HOW TO REMOVE A JAMMED TAPE
CAUTION:
WiperArm Unit maybe damagedorits spring maybe out of place whenthe jammedtape is
removedbyforce.
Remove a jammedtape as follows:
5.1.8.1. Manual Method
Whena tape jamis encountered, check the tape loading condition and use the following
procedure toremove a tape jam.
Fig. 6-1
5.1.8.1.1. Method -1:
1. Move the Pinch Roller Unitout byunhooking the Pinof Pinch Arm
Unitso that the Pinch Roller isseparated from the Capstan Rotor
Unitshaft. Fig. 6-2
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2. Remove the tape from the tape path.
3. Rewind the tape into the cassette byrotating the Center Clutch
Unitcounterclockwise.
4. Unhook Spring (A)of the Drive Rack Arm.
5. Remove Screw (A).
6. Lift the Cassette UpAss'y. Whilepulling the Cassette UpAss'y
out far enough so that itclears the Drive Rack Arm, slide the Drive
Rack Unitas indicated bythe arrow to remove the cassettetape
from the Cassette UpAss'y.
7. Check the cause of mechanical troubleand repair.
Fig. 6-3
5.1.8.1.2. Method -2:
1. Rotate Loading Motor counterclockwise with needlenose pliers,
etc. so that the Pinch Roller isseparated from the shaft of the
Capstan Rotor Unit.
17

2. Perform Step 2through Step 7of Method -1.
5.1.8.1.3. Method -3:
1. Perform Step 2through Step 7of Method -1.
Note:
After repairing mechanical trouble, make sure that all gear
alignments are correct, especiallythe Wiper Arm Unitand Drive
Rack Unitof Cassette UpAss'y. (Refer to "EJECTPosition
Confirmation"inDISASSEMBLY/ASSEMBLY PROCEDURES.)
5.1.8.2. Electrical Method
Electrical method canonlybe performedwhenthe mechanismis movedbyrotating the Loading
Gear.
CAUTION:
1. Before applying DC Power Supply, be sure to disconnect the
Motor Leads from the Connector P2503.
Otherwise, the Loading Motor Drive IC(IC2501) maybe damaged.
2. Ifloading does not start inapprox. 2seconds after DC Power
Supplyisapplied, DO NOTcontinue to applyDC Power Supply.
Instead, perform "Manual Method."
1. Besure to disconnect the Motor Leads from the Connector P2503.
2. Apply+10.0VDC Power Supplyto the Loading Motor terminals.
3. When the Loading Posts reach the fullyunloaded position,
remove the Power Supply. Fig. 7
4. Rewind the tape into the cassette byturning the Center Clutch
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Unitcounterclockwise.
5. Eject the cassette byapplying+10.0VDC Power Supplyagain.
5.1.9. VCR Test Mode
High Voltage is inhibitedbyconnecting JumperJ801 on the TV/VCR MainC.B.A., however, it is
possible tocheck the VCR evenwhenCRTC.B.A. and Anode Capare removed.
5.1.10. WIRE AND LEAD POSITION DIAGRAM
Fig. 8
5.1.11. DEFEATING THE AUTO TRACKING
To defeat the AutoTracking Function, place the instrument inthe STOP mode and place a
jumperbetweenTP6003 and TP6009 on the TV/VCR MainC.B.A. The tracking will be placedin
the neutral position.
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5.1.12. HOW TO SETTRACKING TO THE NEUTRALPOSITION
Ejecting the cassette tape and thenreinserting it will reset the tracking tothe Neutral position.
5.1.13. BLACK SCREWS ON THE CHASSIS
Black Screws are usedon the MechanismChassis toidentifyscrews that require adjustment.
5.1.14. HOW TO RESETALL COMBINATION VCR MEMORY FUNCTIONS
To reset (clear) the select language, channel autoset and set clock functions totheirinitial
poweron condition (poweron, no cassette inserted), holddownthe PLAY and FF buttons on
the unit togetherformore than5 seconds.
Powerwill shut off.
5.1.15. HOW TO CONFIRM AUTO CLOCK SETFEATURE
1. Connect an RFcablefrom the output of one unitto the input of
the test unit.
2. Select corresponding RFchannels.
3. Playback arecording of P.B.S. channel including clock set data
and confirm thisfeature.
5.1.16. VARIABLE VOLTAGE ISOLATION TRANSFORMER
AnIsolation Transformershouldalways be usedduring the servicing of Combination VCR
whose chassis is not isolatedfromthe AC powerline. Use a transformerof adequate power
rating as this protects the technicianfromaccidentsresulting inpersonal injuryfromelectrical
shocks. It will alsoprotect Combination VCR frombeing damagedbyaccidental shorting that
mayoccurduring servicing.
Also, whentroubleshooting the above type of PowerSupplyCircuit, a variable isolation
transformeris requiredinordertoincrease the input voltage slowly.
5.1.17. SPECIALNOTE
All integratedcircuits and manyothersemiconductordevices are electrostaticallysensitive and
therefore require the special handling techniques describedunderthe
"ELECTROSTATICALLY SENSITIVE (ES) DEVICES" section of this service manual.
5.1.18. REPLACEMENTPROCEDURE FOR LEADLESS (CHIP) COMPONENTS
The following procedures are recommendedforthe replacement of the leadless components
usedinthis unit.
1. Preparation for replacement
A. Soldering Iron
Use apencil-type soldering iron that uses less than 30 watts.
B. Solder
EutecticSolder (Tin63%, Lead 37%)isrecommended.
C. Soldering time
Donot applyheat for more than 4seconds.
D. Preheating
Leadless capacitor must be preheated before installation. -
20