JVC HR-A37U Service Manual
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JVC HR-A37U Service Manual

Video cassette recorder
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SERVICE MANUAL
VIDEO CASSETTE RECORDER

SPECIFICATIONS

GENERAL
Power requirement
: AC 120 V~ , 60 Hz
Power consumption
[HR-A57U]
Po wer on
: 18 W
Power off
: 2.0 W
[HR-A37U]
Po wer on
: 16 W
Power off
: 2.0 W
T e mperature
Operating
: 5°C to 40°C (41°F to 104°F)
Stor age
: –20°C to 60°C (–4°F to140°F)
Operating position
: Horizontal only
Dimensions (W x H x D) : 360 mm x 94 mm x 247 mm
(14-3/16" x 3-3/4" x 9-3/4")
Weight
: 3.0 kg (6.6 lbs)
Format
: VHS NTSC sta ndard
Maximum recording time
SP
: 210 min. with ST-210 video cassette
EP
: 630 min. with ST-210 video cassette
VIDEO/AUDIO
Signa l s ystem
: NTS C-type color signal and E IA
monochrome signal, 525 lines/
60 fields
Recording/Pla yback
: DA-4 (Double Azimuth) head helical
system
sc an syste m
Signa l-to-noise ratio
: 45 dB
Horizontal resolution
: 230 lines
HR-A37U
(The specifications shown pertain specifically to the model HR-A57U/A37U)
Frequency range
[HR-A57U]
Normal audio
: 70 Hz to 10,000 Hz
Hi-Fi audio
: 20 Hz to 20,000 Hz
[HR-A37U]
Normal audio
: 70 Hz to 10,000 Hz
Input/Output
: R CA connectors (IN x 2, OUT x 1)
TUNER
Tuning system
: Frequency-synthesized tuner
Channel coverage
VHF
: Channels 2–13
UHF
: Channels 14–69
CATV
: 113 Channels
R F output
: Channel 3 or 4 (s witchable; preset to
Channel 3 when s hipped) 75 ohms,
unbalanced
TIMER
Clock reference
: Quartz
P rogram capacity
: 1-year programmable timer/
8 programs
Memory backup for timer is not supported.
ACCESSORIES
Pr ovided accessor ies
: R F cable (F- type),
Infrared remote control unit,
"AA" battery x 2
Specif ications shown are for SP mode unless s pecified otherwise.
E. & O.E. Des ign and specifications subject to change without
notice.
No.82836
December 2000

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Summary of Contents for JVC HR-A37U

  • Page 1: Specifications

    SERVICE MANUAL VIDEO CASSETTE RECORDER HR-A37U SPECIFICATIONS (The specifications shown pertain specifically to the model HR-A57U/A37U) Frequency range GENERAL [HR-A57U] Power requirement : AC 120 V~ , 60 Hz Normal audio : 70 Hz to 10,000 Hz Power consumption Hi-Fi audio...

  • Page 3: Table Of Contents

    (take-up side) and main brake assembly (supply side) ....2-13 2.2.21 Tension brake assembly, reel disk (supply side) and tension arm assembly ........2-14 The following table lists the differing points between Models (HR-A37U and HR-A37U(C)) in this series. MODEL HR-A37U HR-A37U(C)

  • Page 4: Important Safety Precautions

    Important Safety Precautions Prior to shipment from the factory, JVC products are strictly inspected to conform 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.
  • Page 5 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 original positions, Afterwards, perform the following tests and confirm the specified values in order to verify compli- ance with safety standards.

  • Page 7: Disassembly

    SECTION 1 DISASSEMBLY 1.3 DISASSEMBLY/ASSEMBLY METHOD 1.1 DISASSEMBLY FLOW CHART Step/ Fig. This flowchart lists the disassembling steps for the cabinet Part Name Point Note Loc No. parts and P.C. boards in order to gain access to item(s) to Top cover D1 2(S1a) - - - - - - - - - - - - - - - - - be serviced.
  • Page 8 Procedures for Lowering the Cassette holder assembly As the mechanism of this unit is integrated with the Housing assembly, the holder must be lowered and the two screws un- screwed when removing the Mechanism assembly. Fig. 2 (L2) Fig. 1 <Note 2b>...
  • Page 9 Note: • When installing the MECHA assembly, secure the screws (S4a) in the order of a , b . (S4a) (S4b) <Note 4a> Foil side <Note 3> (S4c) (L5a) (L5c) Q3002 End sensor <Note 4> (L4) Spacer <Note 4> (L5b) Note 1: •...

  • Page 10: Service Position

    1.5 Mechanism service mode This model has a unique function to enter the mechanism 1.4 Service position into every operation mode without loading of any cassette tape. This function is called the “Mechanism service mode”. This unit has been designed so that the Mechanism and Main board assemblies can be removed together from the chassis assembly.

  • Page 11: Emergency Display Function

    Notes: 1.7 Emergency display function • The EMG detail information <1><2> show the information This unit has a function for storing the history of the past two on the latest EMG. emergencies (EMG) and displaying them on each FDP (or It becomes “...

  • Page 12: Emg Content Description

    1.7.3 EMG content description Note: EMG contents “E08/E09” are for the model with Dynamic Drum (DD). CONTENT CAUSE E01: Loading EMG 1. The mechanism is locked in the middle of mode transition. When the mechanism mode cannot be changed to an- 2.

  • Page 13: Emg Detail Information <1

    1.7.4 EMG detail information <1> * 2 : Mechanism operation mode [Common table of MN* and M3*] The status (electrical operation mode) of the VCR and the sta- tus (mechanism operation mode/sensor information) of the Display Mechanism operation mode mechanism in the latest EMG can be confirmed based on the MN* M3* figure in EMG detail information <1>...

  • Page 14: Emg Detail Information <2

    3– : Mechanism sensor information Note: [Common table of MN*, HD* and M3*] • EMG detail information <2> is the reference information stored using the remaining tape detection function of the Mechanism sensor information Display MN* / HD* cassette tape. As a result, it may not identify cassette cor- REC safety Start S-VHS SW...

  • Page 15: Mechanism Adjustment

    SECTION 2 MECHANISM ADJUSTMENT 2.1 Before starting repair and adjustment 2.1.1 Precautions (1) Unplug the power cord plug of the VCR before using your Loading motor soldering iron. (2) Take care not to cause any damage to the conductor wires when plugging and unplugging the connectors. (3) Do not randomly handle the parts without identifying where the trouble is.

  • Page 16: Jigs And Tools Required For Adjustment

    2. In case of mechanical failure 2.1.4 Jigs and tools required for adjustment If you cannot remove the cassette tape which is loaded be- Roller driver A/C head positioning tool Torque gauge cause of any mechanical failure, manually remove it by tak- PTU94002 PTU94010 PUJ48075-2...

  • Page 17: Maintenance And Inspection

    2.1.5 Maintenance and inspection 1. Location of major mechanical parts In this chapter, the two mechanism speeds are described by comparing the speeds of the standard type and the high-speed FF/REW type. It is possible to distinguish between these two types of mechanism by the diameters of their capstan pulleys. The capstan pulley diameter for the standard type is approx.
  • Page 18 4. Suggested servicing schedule for main components The following table indicates the suggested period for such Guide rail Roller cam assembly service measures as cleaning,lubrication and replacement. In practice, the indicated periods will vary widely according to environmental and usage conditions.However, the indi- cated components should be inspected when a set is brought for service and the maintenance work performed if neces- sary.
  • Page 19 Symbols and numbers R4 R1 T9 T12 T11 B15 B12 B14 B13 B17 B21 B7 B8 B5 B4 B11 T14 T15 T13 T22 T24 T18 B19 Removal parts (Reference items) Replacement parts 2.2.3 Guide rail 2.2.3 Roller cam assembly 2.2.3 Cassette housing bracket 2.2.3 Opener guide 2.2.3 Door opener 2.2.3 Relay gear...

  • Page 20: Replacement Of Major Parts

    2.2 Replacement of major parts 2.2.3 Cassette holder assembly 1. How to remove 2.2.1 Before starting disassembling (Phase matching (1) Remove the guide rail and roller cam assembly. (See between mechanical parts) Fig.2-2-3a.) The mechanism of this unit is closely linked with the rotary (3 lugs on the guide rail and one lug on the roller cam encoder and system controller circuits.
  • Page 21 (5) While holding the left side of the cassette holder, lift the 2. How to install (Phase matching) cassette holder assembly so that the three legs on the (1) Insert the section (A) of the drive arm into the section (B) left side are all released.

  • Page 22: Pinch Roller Arm Assembly

    2.2.6 A/C head Notches Guide hole Notch 1. How to remove Relay gear (1) Remove the two screws (A) and remove the A/C head together with the head base. (2) When replacing only the A/C head, remove the three screws (B) while controlling the compression spring. Head base Screws(A) Drive gear...

  • Page 23: Capstan Motor

    2. How to install (Centering the mounting position) Loading motor board assembly When the capstan motor has once been removed and then reinstalled out of the initial correct position in the rotational Loading motor direction, the capstan motor current may be unstable during Lugs operation in high or low temperatures.

  • Page 24: Rotary Encoder

    2.2.10 Rotary encoder 2.2.12 Change lever assembly, direct gear, clutch gear and coupling gear 1. How to remove (1) Remove the screw (A) and remove the rotary encoder 1. How to remove by pulling it up. (See Fig. 2-2-10a.) (1) Release the two lugs of the rotary encoder guide in the arrow-indicated direction and remove the change lever assembly.

  • Page 25: Link Lever

    2.2.13 Link lever 2.2.14 Cassette gear, control cam and worm gear 1. How to remove 1. How to remove (1) Remove the two slit washers. (1) Remove the control cam by lifting it. (2) Remove the link lever by lifting it from the shaft retained (2) Open the two lugs of the cassette gear outward and pull by the slit washers.

  • Page 26: Loading Arm Gear (Supply Or Take-Up Side) And Loading Arm Gear Shaft

    (3) Install the control plate so that the section A of the load- (3) Turn the loading arm gear (take-up side) clockwise so ing arm gear shaft fits into the hole (A) of the control plate, that the notch of the loading arm gear (take-up side) is the section B of the control plate guide into the hole (B), in alignment with the projection of the loading arm gear and the control plate comes under the section C of the...

  • Page 27: Take-Up Lever,Take-Up Head And Control Plate Guide

    2.2.17 Take-up lever, take-up head and control plate guide (1) Remove the spring of the take-up lever from the main deck. Spring (2) Remove the lug (A) of the take-up lever from the main Sub brake assembly deck and pull out the take-up lever and the take-up head Lug(A) (take-up side) together.

  • Page 28: Tension Brake Assembly, Reel Disk (Supply Side) And Tension Arm Assembly

    2.2.21 Tension brake assembly, reel disk (supply side) 2.2.23 Stator assembly and tension arm assembly (1) Remove the flat cable. 1. How to remove (2) Remove the two screws (A), (B) and remove the lug wire. (1) Remove the three lugs of the tension brake assembly (3) Remove the stator assembly by lifting in the arrow-indi- from the main deck and pull them off.

  • Page 29: Upper Drum Assembly

    2.2.25 Upper drum assembly Notes: • To replace the upper drum assembly only may not be possible with some models. For upper drum assem- bly replacement, refer to the parts list. (When the parts number of the upper drum assembly is not listed on Lower drum assembly the parts list, then this cannot be replaced.) •...

  • Page 30: Compatibility Adjustment

    2.3 Compatibility adjustment pole base assembly (supply or take-up side). (7) Unload the cassette tape once, play back the alignment Notes: tape (A1) again and confirm the V.PB FM waveform. • Although compatibility adjustment is very important, (8) After adjustment, confirm that the tape wrinkling does not it is not necessary to perform this as part of the nor- occur at the roller upper or lower limits.

  • Page 31: Height And Tilt Of The A/C Head

    (4) Adjust the AUDIO OUT waveform and Control pulse waveform by turning the screws (1), (2) and (3) little by little until both waveforms reach maximum. The screw (1) and (3) are for adjustment of tilt and the screw (2) for azi- muth.

  • Page 32: Standard Tracking Preset

    [Perform adjustment steps (7) to (10) only for 2 Head (4) Set the VCR to the Auto adjust mode by transmitting the models equipped with LP mode.] code (F) twice from the Jig RCU. When the VCR enters the stop mode, the adjustment is completed. (7) Then play back the alignment tape (A2).
  • Page 33 Mechanism Timing Chart EJECT CASS- Mechanism mode CASS-INS FF/REW STOP SLOW/STILL PLAY Control plate mark HIGH C CH HIGH Rotary encoder B CH HIGH A CH Control cam angle 264. 318. 412. Rotary encoder 114. 150. 167. 178. 207. 218. 240.

  • Page 35: Electrical Adjustment

    SECTION 3 ELECTRICAL ADJUSTMENT 3.1.4 Switch settings and standard precautions Precaution The SW settings of the VCR and the standard precautions The following adjustment procedures are not only necessary for the electrical adjustments are as follows. after replacement of consumable mechanical parts or board assemblies, but are also provided as references to be re- •...

  • Page 36: Servo Circuit

    Servo circuit Note: • For FWD slow (+1/6x) playback, transmit the code “08” 3.2.1 Switching point from the Jig RCU to enter the slow playback mode, and Signal (A1) • Stairstep signal transmit the code “D0” for REV slow (–1/6x) mode. (A2) •...
  • Page 38 JVC SERVICE & ENGINEERING COMPANY OF AMERICA DIVISION OF JVC AMERICAS CORP. Head office 1700 Valley Road Wayne, New Jersey 07470-9976 (973)315-5000 (973)396-1000 East Coast 10 New Maple Avenue Pine Brook, New Jersey 07058-9641 705 Enterprise Street Aurora, Illinois 60504-8149...

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