FUNAI 31B 750, 31A-850 SERVICE MANUAL

SERVICE MANUAL
Main Section
I Specifications I Preparation for Servicing I Adjustment Procedures I Schematic Diagrams I CBA’s I Exploded views I Parts List
When servicing the deck mechanism, refer to MK14 Deck Mechanism Section.
Deck Mechanism Part No.: N25E0FL
VIDEO CASSETTE RECORDER
31B-750
31A-850
PAL
MAIN SECTION
VIDEO CASSETTE RECORDER
31B-750/31A-850
Sec. 1: Main Section
I Specifications I Preparation for Servicing I Adjustment Procedures I Schematic Diagrams I CBA’s I Exploded Views I Parts List
TABLE OF CONTENTS
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1-1
Important Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2-1
Standard Notes for Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3-1
Preparation for Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4-1
Cabinet Disassembly Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5-1
Electrical Adjustment Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6-1
How to Initialize the VCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7-1
Function Indicator Symbols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8-1
Block Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9-1
Schematic Diagrams / CBA’s and Test Points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10-1
Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11-1
Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-12-1
IC Pin Function Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13-1
Lead Identifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14-1
Exploded Views. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-15-1
Mechanical Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16-1
Electrical Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17-1

SPECIFICATIONS

Description Unit Minimum Nominal Maximum Remark
1. Video
1-1. Video Output (PB) Vp-p 0.8 1.0 1.2 FL6A
1-2. Video Output (R/P) Vp-p 0.8 1.0 1.2
1-3. Video S/N Y (R/P) dB 40 45
1-4. Video Color S/N AM (R/P) dB 37 41 SP Mode
1-5. Video Color S/N PM (R/P) dB 30 36 SP Mode
1-6. Resolution (PB) Line 230 245 SP Mode
2. Servo
2-1. Jitter Low µsec 0.07 0.12 SP Mode
2-2. Wow & Flutter % 0.3 0.5 SP Mode
3. Normal Audio
3-1. Output (PB) dBV -9 -6 -3 SP Mode
3-2. Output (R/P) dBV -9 -6 -1.5 SP Mode
3-3. S/N (R/P) dB 36 41 SP Mode
3-4. Distortion (R/P) % 1.0 4.0 SP Mode
3-5. Freq. resp (R/P) at 200Hz dB -7 -4 SP Mode
(-20dB ref. 1kHz) at 6kHz dB -10 -4 SP Mode
SP Mode,
W/O Burst
4. Tuner
4-1. Video output Vp-p 0.8 1.0 1.2 E-E Mode
4-2. Video S/N dB 39 42 E-E Mode
4-3. Audio output dB -10 -6 -2 E-E Mode
4-4. Audio S/N dB 40 46 E-E Mode
5. Hi-Fi Audio
5-1. Output dBV -12 -8 -4 SP Mode
5-2. Dynamic Range dB 70 85 SP Mode
5-3. Freq. resp (6dB B.W) Hz 20 ~ 20K SP Mode
Note: Nominal specs represent the design specs. All units should be able to approximate these – some will exceed and some may drop slightly below these specs. Limit specs represent the absolute worst condition that still might be considered acceptable; In no case should a unit fail to meet limit specs.
1-1-1 HM4N0SP

IMPORTANT SAFETY PRECAUTIONS

Product Safety Notice
Some electrical and mechanical parts have special safety-related characteristics which are often not evi­dent from visual inspection, nor can the protection they give necessarily be obtained by replacing them with components rated for higher voltage, wattage, etc. Parts that have special safety characteristics are identified by a ! on schematics and in parts lists. Use of a substitute replacement that does not have the same safety characteristics as the recommended replacement part might create shock, fire, and/or other hazards. The Product’s Safety is under review continu­ously and new instructions are issued whenever appropriate. Prior to shipment from the factory, our products are carefully inspected to confirm with the recognized product safety and electrical codes of the countries in which they are to be sold. However, in order to maintain such compliance, it is equally impor­tant to implement the following precautions when a set is being serviced.
Precautions during Servicing
A. Parts identified by the ! symbol are critical for
safety. Replace only with part number specified.
B. In addition to safety, other parts and assemblies
are specified for conformance with regulations applying to spurious radiation. These must also be replaced only with specified replacements. Examples: RF converters, RF cables, noise block­ing capacitors, and noise blocking filters, etc.
C. Use specified internal wiring. Note especially:
1)Wires covered with PVC tubing
2)Double insulated wires
3)High voltage leads
D. Use specified insulating materials for hazardous
live parts. Note especially:
1)Insulation tape
2)PVC tubing
3)Spacers
4)Insulators for transistors
E. When replacing AC primary side components
(transformers, power cord, etc.), wrap ends of wires securely about the terminals before solder­ing.
F. Observe that the wires do not contact heat produc-
ing parts (heatsinks, oxide metal film resistors, fus­ible resistors, etc.).
G. Check that replaced wires do not contact sharp
edges or pointed parts.
H. When a power cord has been replaced, check that
5 - 6 kg of force in any direction will not loosen it.
I. Also check areas surrounding repaired locations.
J. Be careful that foreign objects (screws, solder
droplets, etc.) do not remain inside the set.
K. Crimp type wire connector
The power transformer uses crimp type connectors which connect the power cord and the primary side of the transformer. When replacing the transformer, follow these steps carefully and precisely to pre­vent shock hazards. Replacement procedure
1)Remove the old connector by cutting the wires at a point close to the connector.
Important: Do not re-use a connector. (Discard it.)
2)Strip about 15 mm of the insulation from the ends of the wires. If the wires are stranded, twist the strands to avoid frayed conductors.
3)Align the lengths of the wires to be connected. Insert the wires fully into the connector.
4)Use a crimping tool to crimp the metal sleeve at its center. Be sure to crimp fully to the complete clo­sure of the tool.
L. When connecting or disconnecting the internal
connectors, first, disconnect the AC plug from the AC outlet.
1-2-1 U31P_ISP
Safety Check after Servicing
Examine the area surrounding the repaired location for damage or deterioration. Observe that screws, parts, and wires have been returned to their original positions. Afterwards, do the following tests and con­firm the specified values to verify compliance with safety standards.
1. Clearance Distance
When replacing primary circuit components, confirm specified clearance distance (d) and (d’) between sol­dered terminals, and between terminals and surround­ing metallic parts. (See Fig. 1)
Table 1 : Ratings for selected area
AC Line Voltage Clearance Distance (d), (d’)
220 to 240 V
Note: This table is unofficial and for reference only.
Be sure to confirm the precise values.
3mm(d)
6 mm(d’)
2. Leakage Current Test
Confirm the specified (or lower) leakage current between B (earth ground, power cord plug prongs) and externally exposed accessible parts (RF termi­nals, antenna terminals, video and audio input and output terminals, microphone jacks, earphone jacks, etc.) is lower than or equal to the specified value in the table below.
Measuring Method (Power ON) :
Insert load Z between B (earth ground, power cord plug prongs) and exposed accessible parts. Use an AC voltmeter to measure across the terminals of load Z. See Fig. 2 and the following table.
Chassis or Secondary Conductor
Primary Circuit
d' d
Exposed Accessible Part
Z
One side of
B
Power Cord Plug Prongs
AC Voltmeter (High Impedance)
Fig. 1
Fig. 2
Table 2: Leakage current ratings for selected areas
AC Line Voltage Load Z Leakage Current (i)
2kRES.
Connected in
parallel
220 to 240 V
50k RES.
Connected in
parallel
Note: This table is unofficial and for reference only. Be sure to confirm the precise values.
i0.7mA AC Peak
i2mA DC
i0.7mA AC Peak
i2mA DC
1-2-2 U31P_ISP
One side of power cord plug
prongs (B) to:
RF or
Antenna terminals
A/V Input, Output

STANDARD NOTES FOR SERVICING

Circuit Board Indications
1. The output pin of the 3 pin Regulator ICs is indicated as shown.
Top View
Out
2. For other ICs, pin 1 and every fifth pin are indicated as shown.
Pin 1
3. The 1st pin of every male connector is indicated as shown.
Pin 1
Input
In
Bottom View
5
10
Pb (Lead) Free Solder
When soldering, be sure to use the Pb free solder.
How to Remove / Install Flat Pack-IC
1. Removal
With Hot-Air Flat Pack-IC Desoldering Machine:
1. Prepare the hot-air flat pack-IC desoldering machine, then apply hot air to the Flat Pack-IC (about 5 to 6 seconds). (Fig. S-1-1)
Fig. S-1-1
2. Remove the flat pack-IC with tweezers while applying the hot air.
3. Bottom of the flat pack-IC is fixed with glue to the CBA; when removing entire flat pack-IC, first apply soldering iron to center of the flat pack-IC and heat up. Then remove (glue will be melted). (Fig. S-1-6)
4. Release the flat pack-IC from the CBA using tweezers. (Fig. S-1-6)
CAUTION:
1. The Flat Pack-IC shape may differ by models. Use an appropriate hot-air flat pack-IC desoldering machine, whose shape matches that of the Flat Pack-IC.
2. Do not supply hot air to the chip parts around the flat pack-IC for over 6 seconds because damage to the chip parts may occur. Put masking tape around the flat pack-IC to protect other parts from damage. (Fig. S-1-2)
1-3-1 VCRP_SN
3. The flat pack-IC on the CBA is affixed with glue, so be careful not to break or damage the foil of each pin or the solder lands under the IC when removing it.
With Soldering Iron:
1. Using desoldering braid, remove the solder from all pins of the flat pack-IC. When you use solder flux which is applied to all pins of the flat pack-IC, you can remove it easily. (Fig. S-1-3)
CBA
Masking Tape
Tweezers
Hot-air Flat Pack-IC Desoldering Machine
Flat Pack-IC
Fig. S-1-2
Flat Pack-IC
Desoldering Braid
Soldering Iron
Fig. S-1-3
2. Lift each lead of the flat pack-IC upward one by one, using a sharp pin or wire to which solder will not adhere (iron wire). When heating the pins, use a fine tip soldering iron or a hot air desoldering machine. (Fig. S-1-4)
Sharp Pin
Fine Tip Soldering Iron
3. Bottom of the flat pack-IC is fixed with glue to the CBA; when removing entire flat pack-IC, first apply soldering iron to center of the flat pack-IC and heat up. Then remove (glue will be melted). (Fig. S-1-6)
4. Release the flat pack-IC from the CBA using tweezers. (Fig. S-1-6)
Fig. S-1-4
1-3-2 VCRP_SN
With Iron Wire:
1. Using desoldering braid, remove the solder from all pins of the flat pack-IC. When you use solder flux which is applied to all pins of the flat pack-IC, you can remove it easily. (Fig. S-1-3)
2. Affix the wire to a workbench or solid mounting point, as shown in Fig. S-1-5.
3. While heating the pins using a fine tip soldering iron or hot air blower, pull up the wire as the solder melts so as to lift the IC leads from the CBA contact pads as shown in Fig. S-1-5.
4. Bottom of the flat pack-IC is fixed with glue to the CBA; when removing entire flat pack-IC, first apply soldering iron to center of the flat pack-IC and heat up. Then remove (glue will be melted). (Fig. S-1-6)
5. Release the flat pack-IC from the CBA using tweezers. (Fig. S-1-6)
Note: When using a soldering iron, care must be
taken to ensure that the flat pack-IC is not being held by glue. When the flat pack-IC is removed from the CBA, handle it gently because it may be damaged if force is applied.
Hot Air Blower
2. Installation
1. Using desoldering braid, remove the solder from the foil of each pin of the flat pack-IC on the CBA so you can install a replacement flat pack-IC more easily.
2. The “” mark on the flat pack-IC indicates pin 1. (See Fig. S-1-7.) Be sure this mark matches the 1 on the PCB when positioning for installation. Then presolder the four corners of the flat pack-IC. (See Fig. S-1-8.)
3. Solder all pins of the flat pack-IC. Be sure that none of the pins have solder bridges.
Example :
Pin 1 of the Flat Pack-IC is indicated by a " " mark.
Fig. S-1-7
To Solid Mounting Point
CBA
Tweezers
Iron Wire
Soldering Iron
Fig. S-1-5
Fine Tip Soldering Iron
Flat Pack-IC
or
Presolder
Flat Pack-IC
CBA
Fig. S-1-8
Fig. S-1-6
1-3-3 VCRP_SN
Instructions for Handling Semi­conductors
Electrostatic breakdown of the semi-conductors may occur due to a potential difference caused by electrostatic charge during unpacking or repair work.
1. Ground for Human Body
Be sure to wear a grounding band (1 M) that is properly grounded to remove any static electricity that may be charged on the body.
2. Ground for Workbench
Be sure to place a conductive sheet or copper plate with proper grounding (1 M) on the workbench or other surface, where the semi-conductors are to be placed. Because the static electricity charge on clothing will not escape through the body grounding band, be careful to avoid contacting semi-conductors with your clothing.
<Incorrect>
<Correct>
1M
CBA
Grounding Band
1M
CBA
Conductive Sheet or Copper Plate
1-3-4 VCRP_SN

PREPARATION FOR SERVICING

How to Enter the Service Mode
About Optical Sensors
Caution:
An optical sensor system is used for the Tape Start and End Sensors on this equipment. Carefully read and follow the instructions below. Otherwise the unit may operate erratically.
What to do for preparation
Insert a tape into the Deck Mechanism Assembly and press the PLAY button. The tape will be loaded into the Deck Mechanism Assembly. Make sure the power is on, connect TP507 (S-INH) to GND. This will stop the function of Tape Start Sensor, Tape End Sensor and Reel Sensors. (If these TPs are connected before plugging in the unit, the function of the sensors will stay valid.) See Fig. 1.
Note: Because the Tape End Sensors are inactive, do not run a tape all the way to the start or the end of the tape to avoid tape damage.
Q505
Q504
TP507
S-INH
Fig. 1
1-4-1 HM4N0PFS

CABINET DISASSEMBLY INSTRUCTIONS

1. Disassembly Flowchart
This flowchart indicates the disassembly steps to gain access to item(s) to be serviced. When reassembling, follow the steps in reverse order. Bend, route, and dress the cables as they were originally.
[1] Top Case
[2] Front Assembly
[3] VCR Chassis Unit
[4] Jack CBA
[5] Deck Assembly
[6] Main CBA
[7] Cylinder Shield
[8] Jack Board
2. Disassembly Method
REMOVAL
ID/
LOC
.No.
PART
REMOVE/*UNHOOK/
Fig.
UNLOCK/RELEASE/
No.
UNPLUG/DESOLDER
Note
(1): Identification (location) No. of parts in the figures (2): Name of the part (3): Figure Number for reference (4): Identification of parts to be removed, unhooked,
unlocked, released, unplugged, unclamped, or desoldered. P=Spring, L=Locking Tab, S=Screw, CN=Connector *=Unhook, Unlock, Release, Unplug, or Desolder e.g. 2(S-2) = two Screws (S-2), 2(L-2) = two Locking Tabs (L-2)
(5): Refer to “Reference Notes.”
Reference Notes
CAUTION: Locking Tabs (L-1) and (L-2) are fragile. Be careful not to break them.
1. Remove five Screws (S-2), three Screws (S-3) and
Screw (S-4). Then, slowly lift the VCR Chassis Unit (Deck Assembly, Jack CBA and Main CBA) up.
2. When reassembling, solder wire jumpers as shown
in Fig. D5.
3. Before installing the Deck Assembly, be sure to
place the pin of LD-SW on Main CBA as shown in Fig. D6. Then, install the Deck Assembly while aligning the hole of Cam Gear with the pin of LD­SW, the shaft of Cam Gear with the hole of LD-SW as shown in Fig. D6.
[1] Top Case D1 7(S-1) -
Front
[2]
Assembly
VCR Chassis
[3]
Unit
[4] Jack CBA D4 Desolder, (S-5) -
Deck
[5]
Assembly
[6] Main CBA D5 ---------- -
Cylinder
[7]
Shield
[8] Jack Board D5 *(L-3) -
(1)
(2)
D2 *3(L-1),*4(L-2) -
D3 5(S-2), 3(S-3), (S-4) 1
D5
2(S-6), Desolder 2,3
D6
D5 (S-7) -
(3)
(4)
(S-1)
(S-1)
[1] Top Case
(S-1)
(5)
Fig. D1
1-5-1 HM4N0DC
(L-2)
[2] Front Assembly
(S-2)
(S-3)
[3]VCR Chassis Unit
(L-1)
(S-3)
(S-2)
(L-2)
(S-2)
[4] Jack CBA
(S-5)
Desolder
Fig. D4
Fig. D2
(S-4)
(S-3)
(S-2)
Fig. D3
1-5-2 HM4N0DC
[7] Cylinder Shield
FE Head
Cylinder Assembly
(S-7)
ACE Head Assembly
Pin
SW507 LD-SW
[6] Main CBA
[8] Jack Board
(L-3)
From
From FE Head
Cylinder Assembly
(S-6)
TOP VIEW
From ACE Head Assembly
[5] Deck Assembly
[6] Main CBA
(S-6)
From Capstan Motor Assembly
Lead with blue stripe
[5] Deck Assembly
Shaft
Hole
LD-SW
Cam Gear
Hole
Pin
[6] Main CBA
Fig. D6
Printing
Lead with white stripe
Lead connections of Deck Assembly and Main CBA
Lead with blue stripe
Desolder from bottom
side
Fig. D5
1-5-3 HM4N0DC

ELECTRICAL ADJUSTMENT INSTRUCTIONS

General Note: "CBA" is an abbreviation for "Circuit Board Assembly."
NOTE:
1.Electrical adjustments are required after replacing circuit components and certain mechanical parts. It is important to do these adjustments only after all repairs and replacements have been com­pleted. Also, do not attempt these adjustments unless the proper equipment is available.
2.To perform these alignment / confirmation proce­dures, make sure that the tracking control is set in the center position: Press either "CHANNEL L5??" or "CHANNEL K" button on the remote control unit first, then the "PLAY" button (Front Panel only).
Test Equipment Required
1.Oscilloscope: Dual-trace with 10:1 probe, V-Range: 0.001~50V/Div., F-Range: DC~AC-20MHz
2.Alignment Tape (FL6A)
Head Switching Position Adjustment
Purpose:
To determine the Head Switching position during playback.
Symptom of Misadjustment:
May cause Head Switching noise or vertical jitter in the picture.
Test point Adj.Point Mode Input
J23(V-OUT)
TP502(RF-SW)
GND
Tape
FL6A Oscilloscope
Connections of Measurement Equipment
Main CBA
VR501
(Switching Point)
(MAIN CBA)
Measurement
Equipment
J23
GND
TP502
PLAY
(SP)
6.5H±1H
(416µs±64µs)
Oscilloscope
-----
Spec.
CH1 CH2 Trig. (+)
Figure 1
EXT. Syncronize Trigger Point
CH1
CH2
Reference Notes: Playback the Alignment tape and adjust VR501 so that the V-sync front edge of the CH1 video output wave­form is at the 6.5H±1H (416µs±64µs) delayed position from the rising edge of the CH2 head switching pulse waveform.
1.0H
6.5H+/-1H (416µs+/-64µs)
Switching Pulse
0.5H V-Syn c
1-6-1 FEGVCREA

HOW TO INITIALIZE THE VCR

To put the program back at the factory-default, initialize the VCR as the following procedure.
1. Make sure that no timer programming is set. If not, reset all timer programming.
2. Turn the power off.
3. Press the [STOP/EJECT] button and [CHANNEL K] button on the unit simultaneously for at least 2 seconds. Upon completion of the initialization of the EEPROM, “ ” mark on the display turns on a light.
4. Release the [STOP/EJECT] button and [CHANNEL K] button to complete this mode.
1-7-1 HM410INT

FUNCTION INDICATOR SYMBOLS

Note:
The following symbols will appear on the indicator panel to indicate the current mode or operation of the VCR. On-screen modes will also be momentarily displayed on the tv screen when you press the operation buttons.
Display panel
MODE INDICATOR ACTIVE
POWER ON " PWR." ON
CASSETTE "IN" CASSETTE "OUT"
CLOCK " 88:88 " ON
REC " REC " ON
REC PAUSE " REC " Blinks at 0.8Hz interval
T- R E C , O T R
RF OUT RF out channel number is displayed on the indicator panel.
S-INH condition All modes Blinks at 0.8Hz interval
All lighting mode All characters ON
" " " "
" "
ON OFF
ON (T-REC OFF,T-REC incomplete Blinks at 0.8Hz interval)
1-8-1 HM4N0FIS
TV screen
Note:
OSD for mechanical error will be displayed for 5 sec. after the mechanical error occurs.
Cause Indicator Active
When reel or capstan mechanism is not functioning correctly
When tape loading mechanism is not functioning correctly
When cassette loading mechanism is not functioning correctly
When the drum is not working properly
P-ON Power safety detection
When reel or capstan mechanism is not functioning correctly
A
R
When tape loading mechanism is not functioning cor­rectly
A R” is displayed on a TV screen. (Refer to Fig. 1.)
A T” is displayed on a TV screen. (Refer to Fig. 2.)
A C” is displayed on a TV screen. (Refer to Fig. 3.)
A D” is displayed on a TV screen. (Refer to Fig. 4.)
A P” is displayed on a TV screen. (Refer to Fig. 5.)
Fig. 1
When the drum is not working properly
A
D
P-ON Power safety detection
Fig. 4
A
T
Fig. 2
When cassette loading mechanism is not functioning correctly
A
C
Fig. 3
A
P
Fig. 5
1-8-2 HM4N0FIS
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