Sharp VP 8, 37VT-26HGY Service Manual

SERVICE MANUAL

37VT-26H(GY)

SERVICE MANUAL

S99P337VT26H/

TV/VCR COMBINATION

TELEVIDEO

Chassis No. VP-8

37VT-26H(GY)

TV/VCR COMBINATION TELEVIDEO

Ë AIS (Automatic Instruction System) Ë ASS (Automatic Sorting System) Ë VPS/PDC (Video Program System / Program Delivery

Control)

Ë FASTEXT Ë VIDEO Plus+ Ë Post Cord Security Ë On Screen Digital Channel/Sound Level/Tuning Display,

Control (Contrast, Colour, Brightness, Tint, Sharpness, White temp) Symbol and Level

Ë Blue Back Off Timer Ë 52 Key, Wireless Remote Control Unit

MODEL 37VT-26H(GY)

» SPECIFICATIONS ................................................................................................................................................................................. 2

» IMPORTANT SERVICE NOTES............................................................................................................................................................ 3

» LOCATION OF USER'S CONTROL ...................................................................................................................................................... 4

» DISASSEMBLY AND REASSEMBLY .................................................................................................................................................... 6

» ADJUSTMENT OF THE TV ELECTRICAL CIRCUITRY ........................................................................................................................9

» PRECAUTIONS IN REASSEMBLING ................................................................................................................................................ 19

» FUNCTION OF MAJOR MECHANICAL PARTS ................................................................................................................................. 20

» ADJUSTMENT, REPLACEMENT AND ASSEMBLY OF MECHANICAL UNITS ................................................................................. 22

» ADJUSTMENT OF THE VCR ELECTRICAL CIRCUITRY ...................................................................................................................41

» MECHANISM OPERATION FLOWCHART AND TROUBLESHOOTING GUIDE ...............................................................................44

» CHASSIS LAYOUT .............................................................................................................................................................................. 63

» BLOCK DIAGRAM OF TV SECTION.................................................................................................................................................. 64

» BLOCK DIAGRAM OF VCR SECTION............................................................................................................................................... 66

» DESCRIPTION OF SCHEMATIC DIAGRAM ...................................................................................................................................... 75

» SOLID STATE DEVICE BASE DIAGRAM ........................................................................................................................................... 76

» WAVEFORMS .....................................................................................................................................................................................77

» SCHEMATIC DIAGRAM ...................................................................................................................................................................... 78

» PRINTED WIRING BOARD ASSEMBLIES......................................................................................................................................... 92

» REPLACEMENT PARTS LIST ............................................................................................................................................................ 99

» PACKING OF THE SET..................................................................................................................................................................... 115

MODEL

In the interests of user-safety (Required by safety regulations in some countries) the set should be restored to its original condition and only parts identical to those specified be used.

FEATURE

Ë Channel Skip Ë High Speed and Double Speed Video Search System

Ë DPSS (Digital Program Search System) Ë Quick Start Playback with Full Loading System Ë Digital Automatic Tracking Control Ë Automatic Playback Function Ë AHC (Automatic Head Cleaning System) Ë Sharp Super Picture Ë 345 Times Hi-Speed FF/REW

CONTENTS

37VT-26H(GY)

» PAL : 3 times/7 times (SP/LP) » NTSC : 3 times/5 times (SP/LP)

5 times/15 times (EP)

Page

WARNING

The chassis in this receiver is partially hot. Use an isolation transformer between the line cord plug and power receptacle, when servicing this chassis. To prevent electric shock, do not remove cover. No user – serviceable parts inside. Refer servicing to qualified service personnel.

SHARP CORPORATION

37VT-26H(GY)

OUTLINE OF THE PRODUCT

Receiving Broadcast Standard: I

Antenna Input Impedance: VHF/UHF;75 ohm Unbalanced (DIN)

TV SECTION

SPECIFICATIONS

Power Source: 220~240 V AC, 50 Hz

Power Consumption: 77 W

Receiving Channel: VHF; 1A~S36

UHF; S37~C57

Receiving System: Sound; 6.0 MHz

Colour; PAL

Video Signal: Input; 0.5-2.0 Vp-p/75 ohm (SCART/RCA)

Output; 1.0 Vp-p/75 ohm (SCART)

Audio Signal: Input; 0.5 Vrms/10k ohm (SCART/RCA)

Output; 0.5 Vrms/1k ohm (SCART) (54% MOD)

Temperature: Operation; 5°C to 40°C

Storage; -10°C to 60°C

Dimensions (Approx.): 378 mm (W) × 387 mm (H) × 384 mm (D)

Weight (Approx.): 12.7 kg

Cabinet Material: Plastic

Accessories: Operation Manual

Infrared Remote Control Unit Dry Batteries, Type AA (×2 pcs.)

Viewing Area: 33.54 cm Diagonal Measurement

Picture Power: 22.0 kV at 800 µA Beam Current

Speaker Output: 3.0 W at Max. (5×9 cm oval type ×1pc.)

Picture Tube: T ype; VB370BVBK1S-S (Tint T ube)

Heater; 6.3 V, 300 mA Focus; High Bi-Potential Electrostatic

VCR SECTION

Outline: VHS Video System Colour Video Cassette Recorder Format: VHS PAL/NTSC Standard

Video Recording System: Rotary Slant Azimuth 2-Head Helical Scan System

Luminance: FM Recording

Chrominance: Low Frequency Converted Direct Recording

Video Signal System: PAL/NTSC 3.58MHz Colour

Cassette Tape: VHS T ype Video Cassette T ape

Tape Width: 12.7 mm

Tape Speed: PAL ; 23.39 mm/s (SP), 11.70 mm/s (LP)

NTSC ; 33.35 mm/s (SP), 16.68 mm/s (LP·PB only), 11.12 mm/s (EP)

Recording/Playback Time: SP ; Max. 240 min (with E-240)

LP ; Max. 480 min (with E-240, PAL only) EP ; Max. 480 min (with T-160, NTSC only)

Number of Video Head: 4 pcs.

Note: The antenna must correspond to the new standard DIN 45325 (IEC 169-2) for combined UHF antenna with

75 ohm connector.

Specifications are subject to change without prior notice.

IMPORTANT SERVICE NOTES

Maintenance and repair of this receiver should be done by qualified service personnel only.

SERVICING OF HIGH VOLTAGE SYSTEM AND PICTURE TUBE

When servicing the high voltage system, remove static charge fr om it by connecting a 10k ohm Resistor in series with an insulated wire (such as a test probe) between picture tube dag and 2nd anode lead. (A C line cord should be disconnected from AC outlet.)

1. Picture tube in this receiver employs integral implosion protection.

2. Replace with tube of the same type number for continued safety.

3. Do not lift picture tube by the neck.

4. Handle the picture tube only when wearing shatterproof goggles and after discharging the high voltage completely.

37VT-26H(GY)

X-RAY

This receiver is designed so that any X-Ray radiation is kept to an absolute minimum. Since cer tain malfunctions or servicing may produce potentially hazardous radiation with prolonged exposure at close range, the following precautions should be observed:

1. When repairing the circuit, be sure not to increase the high voltage to more than 25.3 kV, (at beam 0 µA) for the set.

2. T o keep the set in a normal operation, be sure to make it function on 22.0 kV + 1.5 kV – 2.0 kV (at beam 800 µA) in the case of the set. The set has been factory – Adjusted to the above-mentioned high voltage. ∴ If there is a possibility that the high voltage fluctuates as a result of the repair s, never

forget to check for such high voltage after the work.

3. Do not substitute a picture tube with unauthorized types and/or brands which may cause excess X-ray radiation.

BEFORE RETURNING THE RECEIVER

Before returning the receiver to the user , perform the following saf ety checks.

1. Inspect all lead dress to make certain that leads are not pinched or that hardware is not lodged between the chassis and other metal parts in the receiver.

2. Inspect all protective devices such as non-metallic control knobs, insulating fishpapers, cabinet backs, adjustment and compartment covers or shields, isolation resistor-capacity networks, mechanical insulators etc.

37VT-26H(GY)

LOCATION OF USER'S CONTROL

LOCATION OF USER'S CONTROL (CONTINUED)

37VT-26H(GY)

DISASSEMBLY AND REASSEMBLY

1. Remove the 11 rear cover fixing screws and detach the rear cover.

2. Take out the anode cap, CRT PWB, connectors H, G and F, coating ground, SP chip, fixing screws and others.

3. Remove the Main PWB fixing screws and take out the Main PWB unit and the Power PWB.

4. Remove the 4 Power PWB fixing screws, and take out the Power PWB unit.

37VT-26H(GY)

DISASSEMBLY AND REASSEMBLY (CONTINUED)

5. Remove the 8 VCR fixing screws, and detach the shielding case.

6. Remove the 4 cassette housing control fixing screws, and detach the cassette housing control.

7. Remove the 7 mechanism chassis fixing screws, and detach the mechanism chassis from the Main PWB.

8. Remove the 3 Main PWB fixing screws, and detach the Main PWB.

9. Remove the 2 Tuner/Def and IF PWB fixing screws, and detach the Tuner/Def and IF PWB.

37VT-26H(GY)

DISASSEMBLY AND REASSEMBLY (CONTINUED)

For servicing any of the components inside, disconnect the lead dressing holder . Position the main PWB unit upright as shown below and connect the leads for starting the services.

Note: Fit the VCR unit the front cabinet with the front flap door tilted at 70~80°.

70~80°

ADJUSTMENT OF THE TV ELECTRICAL CIRCUITRY

ADJUSTMENT PRECAUTIONS

1. Calling the service mode

Get the service test points (TP2002 and TP2003) of the set short-circuited.

2. Getting out of the service mode

Get the above service test points open.

3. On-screen display in the service mode

A service mode item and its data appear in two lines at the lower left on the screen.

Top line : Service mode item (See below)

Bottom line : Data (See below)

37VT-26H(GY)

Service mode

Item Display Data Variable range DIRECT MODE → Adjustable in the DIRECT MODE V-AMPLITUDE V-AMP 0 ~ 127 R CUT OFF (0 ~ 255) V-LINEARITY V-LIN 0 ~ 31 G CUT OFF (0 ~ 255) V-OUT PHASE V-POS 0 ~ 7 B CUT OFF (0 ~ 255) H-POSITION H-POS 0 ~ 31 G DRIVE GAIN (0 ~ 255) BELL FILTER BELL 0 ~ 3 B DRIVE GAIN (0 ~ 255) R-Y BLACK OFFSET R-Y 0 ~ 15 B-Y BLACK OFFSET B-Y 0 ~ 15 Y-SUB CONTRAST CONT 0 ~ 31 SUB COLOUR COLOR 0 ~ 240 SUB BRIGHT BRI 0 ~ 150 SUB TINT TINT 0 ~ 37

Note :

Item selectable by the CH '" keys and data by the VOL '" keys (effective on both the remote controller and the set)

The numeric keys on the remote controller work as follows in the DIRECT mode only.

UP DOWN R CUT OFF 1 4 G CUT OFF 2 5 B CUT OFF 3 6 G DRIVE GAIN 7 B DRIVE GAIN 8 0

Õ

õ

Micon version display

Notes :

In all the other modes, these keys are used to select channels. In the DIRECT TUNING mode, these keys are used to enter data.

37VT-26H(GY)

Item-by-item control in the service mode

1. DIRECT mode F-B/W 0 - > 1 (forced B/W)

2. DIRECT mode + HOR. POS. mode DRV CNT 0 - > 1 (drive forced center)

3. R-Y Black Offset CONTRAST MAX (USER-CONTROL)

4. B-Y Black Offset CONTRAST MAX (USER-CONTROL)

5. SUB Tint MUTE MODE Y -MUTE

6. Unspecified items PICTURE NORMAL (CONT. BRI. COL.)

SUB-BRIGHT Initial value R.G.B. CUTOFF 0 (E2PROM data resumed when any of the “0” thru

“9” keys on the remote controller is pressed)

BRIGHT MAX (USER-CONTROL) COLOUR CENTER (USER-CONTROL) R-MONITOR SW 0 - > 1 (MONITOR OUT) MUTE MODE Y-MUTE

BRIGHT MAX (USER-CONTROL) COLOUR CENTER (USER-CONTROL) B-MONITOR SW 0 - > 1 (MONITOR OUT) MUTE MODE Y-MUTE

Note :

All the settings will be back to the initial ones when shifting into any other mode or getting out of the service mode.

Allocation of special keys in the service mode

`HORIZONTAL POSITION key CONFIRM (SET -> S-PICTURE) `Y-MUTE KEY SET `COLOUR MAX./MIN. select key TIMER ON/OFF `DIRECT TUNING MODE KEY RETURN `VCR SLOW TEST KEY PROG `NVM MODE KEY DISPLAY

Adjustment precautions

1) Basically follow the sequential order of adjustments. (Unless otherwise specified, follow the adjustment procedures.)

2) The “`”-marked steps in the adjustment procedures are automatically taken when in the service mode. Leave out these steps.

3) For adjustments in the service mode, it is necessary to have the remote controller at hand.

Trouble indicators

If the set is interrupted by the protectors, the following indicators work to identify a spot in trouble.

1) LED (red) flashing : Deflection system protector activated (high-voltage or beam vert, out protector)

2) REC LED flashing : IIC bus line error (VCJ or tuner, EEPROM, TEXT, PDC)

3) LED off : Power protector activated (+B line short-circuited)

Initial settings of EEPROM data

Initial settings of adjustment items

Item V ariable range Initial setting R CUT OFF 0 ~ 255 0 G CUT OFF 0 ~ 255 0 B CUT OFF 0 ~ 255 0 V-AMPLITUDE 50Hz 0 ~ 127 35 V-AMPLITUDE 60Hz 0 ~ 127 37 V-LINEARITY 50Hz 0 ~ 31 25 V-LINEARITY 60Hz 0 ~ 31 18 V-OUT PHASE 50Hz 0 ~ 7 05 V-OUT PHASE 60Hz 0 ~ 7 02 HORIZONTAL POSITION 50Hz 0 ~ 31 05 HORIZONTAL POSITION 60HZ 0 ~ 31 09 Y-SUB CONTRAST 0 ~ 31 0 SUB-COLOUR 0 ~ 240 91 SUB-BRIGHT 0 ~ 150 100 G-DRIVE GAIN 0 ~ 255 128 B-DRIVE GAIN 0 ~ 255 128 SUB-TINT 0 ~ 37 20 BELL FO 0 ~ 3 01 R-Y BLACK OFFSET 0 ~ 15 8 B-Y BLACK OFFSET 0 ~ 15 8

37VT-26H(GY)

PICTURE Adjust User setting

Initial setting : NORMAL (CONTRAST at 52, others at CENTER)

37VT-26H(GY)

A=B

ËË

PURITY ADJUSTMENT

1. PURITY ADJUSTMENT

1. First of all, let a beam current of over 400µA flow in the set to warm it up for 30 minutes or longer.

2. Keep the purity magnet in the zero magnetic field in advance. Roughly adjust the static convergence.

3. Receive the green-only colour signal. Adjust the beam current to about 500 µA.

4. Degauss the cathode ray tube enough with the degaussing coil.

ADJUSTMENT

Eastward magnetic field specified

1) Observe the beam landings “a” and “b”, as

shown in just the landings as specified. (

2) If the right and left landings are equally out-

ward, move the deflection yoke forward.

3) If the right or left landing is shifted to the right

or to the left, adjust the opening angle of the purity magnet.

4) Make sure the right and left beam landings are

just as specified about the screen center. Now check the cathode ray tube corners. Be sure that all the landings are at rank “B”.

5) If any other colour appears on the screen,

move the deflection yoke back and forth.

LANDING ERROR

» Outward: Mov e the deflection yoke forward. » Inward: Move the deflection y oke bac kward.

6) Receive the monoscope pattern signal.

RASTER ROTATION

7) Adjust the raster rotation to “0” eastward.

» Adjustment error : 0 ±2 mm

8) Tighten up the deflection coil screws.

» Tightening torque : 11±2 kg

Note : Each time the single-colour key is pressed,

the screen colour changes as follows.

Fig. A

, through a microscope. Ad-

Fig. B, Fig. C

Fig. A

)

Fig. B

Fig. C

Green-only screen

Red-only screen

Single-colour screen cleared

Blue-only screen

ËË

Wedge "a"

Lacqure

Wedge "b" Wedge "c"

Approx.100° Approx.100°

B G R

R G B

B G R

R G B

B G R

R G B

ËË

CONVERGENCE ADJUSTMENT

1. CONVERGENCE ADJUSTMENT (to be done after the purity adjustment)

1. Receive the crosshatch pattern signal.

2. Using the remote controller, call the Normal mode.

STATIC CONVERGENCE

1. Turn the 4-pole magnet to a proper opening an-

gle in order to superimpose the blue and red colours.

2. Turn the 6-pole magnet to a proper opening an-

gle in order to superimpose the green colour over the blue and red colours.

DYNAMIC CONVERGENCE

1. Adjust the convergence on the fringes of the

screen in the following steps.

» Fig. a : Drive the wedge at point “a” and

swing the deflection coil upward.

» Fig. b :Drive the wedges at points “b” and

“c” and swing the deflection coil downward.

» Fig. c : Drive the “c” wedge deeper and

swing the deflection coil rightward.

» Fig. d :Drive the “d” wedge deeper and

swing the deflection coil leftward.

2. Fix all the wedges on the cathode ray tube and

apply glass tape over them.

3. Apply lacquer to the deflection yoke lock screw,

magnet unit (purity, 4-pole and 6-pole magnets), and magnet unit lock screw.

Fig. a

Fig. c

37VT-26H(GY)

Fig. b

Fig. d

Finally receive the red-only and blue-only colour signals and make sure there is no other colour mixed on the screen.

4-pole magnet

6-pole magnet

Purity magnet

Fig. 1

CRT neck

Lacquer

37VT-26H(GY)

ËË

Ë CRT CUT-OFF, BACKGROUND AND SUB-CONTRAST ADJUSTMENT (1)

ËË

1. CRT CUT-OFF (I2C bus data adjustment)

1. Receive the monoscope pattern signal.

2. Put the set in the service mode and call up the DIRECT mode (DIRCT).

3. Set the screen control to 0/10 position.

4. Press the “CONFIRM” key on the remote controller to reach the horizontal centering mode. (S-PICTURE k ey on

the set)

5. Turn the screen control clockwise until the horizontal raster of the first glimmering colour becomes slightly

visible.

6. Adjust the cut-off data of the other two colours until the horizontal raster becomes whitish.

Note : The data can be turned up and down with the above keys.

» R CUT OFF UP “1” KEY » G CUT OFF DOWN “5” KEY » R CUT OFF DOWN “4” KEY » B CUT OFF UP “3” KEY » G CUT OFF UP “2” KEY » B CUT OFF DOWN “6” KEY

7. Turn the screen control counterclockwise until the horizontal raster disappears.

Note : Before starting this adjustment, warm up the unit for 30 min utes or longer at a beam current of over

600 µA.

8. Press the “CONFIRM” k e y on the remote controller to call up the NORMAL mode . (S-PICTURE key on the set)

SUB-BRIGHTNESS (I2C bus data adjustment)

9. Using the remote controller, call the SUB-BRIGHT setting mode (BRI). (Receive the crosshatch and gray scale

signal.)

10.Set the sub-brightness data so that the third black portion (1st to 5th counted from the left of the screen) of the

window pattern looks sinking.

Note : The service mode adjustment in the above steps 9. and 10. should be carried out after the white

balance and background adjustments.

11.Exit from the service mode.

2. WHITE BALANCE AND BACKGROUND (I2C bus data adjustment)

1. Receive the monoscope pattern signal.

2. Put the set in the service mode and call up the DIRECT mode (DIRCT).

3. Connect the beam ammeter between TP601 and TP602.

4. Using the sub-contrast control, roughly adjust the beam current to about 700 µA.

5. Adjust the G-drive and B-drive data to have a colour temperature of 9,000°K (white).

» 9,000°K x : 0.290

y : 0.284

(with a Minolta colour temperature meter CA-100)

Note : The data can be turned up and down with the above keys.

» G-DRIVE UP “7” KEY » B-DRIVE UP “8” KEY » G-DRIVE DOWN “

6. Adjust the contrast and brightness controls to have the beam current of 200 µA or so. Now check the back-

ground colour. If the colour temperature is not as specified, go back to No. 1 on the preceding page.

7. Exit from the service mode.

Note : Before starting this adjustment, warm up the unit for 30 min utes or longer at a beam current of over

600 µA.

Õ

” KEY » B-DRIVE DOWN “0” KEY

õ

ËË

CRT CUT-OFF, BACKGROUND AND SUB-CONTRAST ADJUSTMENT (2)

3. SUB-CONTRAST (I2C bus data adjustment)

1. Receive the crosshatch pattern signal.

2. Put the set in the service mode and select the SUB-CONTRAST mode (CONT).

3. Adjust the sub-contrast data to "0".

4. Exit from the service mode.

ËË

HORIZONTAL AND VERTICAL CIRCUIT ADJUSTMENT

1. SERVICE MODE DATA ADJUSTMENT

Put the set in the service mode.

Turn up or down the data for this adjustment.

I2C bus data adjustment » V-AMP 50 Hz

A) Select the V-AMP mode (V-AMP). Adjust the

overscan to 9% .

» V-LINEARITY - 50 Hz

B) Select the V-LIN mode (V-LIN). Adjust to get the

best linearity.

» V-OUT PHASE - 50 Hz (V-CENTER)

C) Select the V-OUT POS mode (V-POS). Align the

screen center with the cathode ray tube’s geometrical center.

» H-POS 50 Hz (H-CENTER)

D) Select the H-POS mode (H-POS). Make the dis-

tances “A” and “B” on both sides equal.

Exit from the service mode.

Note : The selected channels in parentheses have the following signals.

Monoscope pattern (50 Hz) signal

Fig.2

37VT-26H(GY)

For the V-AMP 60 Hz, V-LINEARITY 60 Hz, V-OUT PHASE 60 Hz, and H-POS 60 Hz adjustments, their corrected data are automatically entered when the corresponding 50-Hz mode adjustments are made. Chec k these data on the 60 Hz mode screen. Readjust any of them if required. (The 50 Hz and 60 Hz modes are selected on the screen.) Once the adjustment has been made in the 60 Hz mode, do not change it in the 50 Hz mode.

2. FOCUS ADJUSTMENT

1. Receive the monoscope pattern signal.

2. Make the PICTURE ADJUST setting to NORMAL.

3. Adjust the focus control so that the middle areas

between the pattern’s center and the screen’ s both ends be in the best focus.

Adjust point

Fig.3

37VT-26H(GY)

YCYG

To be at the same level

ËË

PAL CHROMA ADJUSTMENT

1. SUB-COLOUR ADJUSTMENT (I2C bus data adjustment)

1. Receive the PAL colour bar signal.

2. Put the set in the service mode.

3. Select the sub-colour mode (COL).

4. Connect the oscilloscope to TP1852 (RED cath-

ode). (Use a 10 : 1 probe.)

» Range: 20 V/div . » Sweep time: 20 µsec/div.

5. Adjust the sub-colour data so that the 75% white

and red portions of the PAL colour bar be at the same level. See

6. Exit from the service mode.

» When getting out of the SUB-COLOUR mode,

the sub-colour data turns up 15.

ËË

NTSC CHROMA ADJUSTMENT

Fig. 4

1. SUB-TINT ADJUSTMENT (I2C bus data adjustment)

1. Receive the NTSC colour bar signal.

2. Put the set in the service mode.

3. Select the SUB-TINT mode (TINT).

4. Connect the oscilloscope to TP802 (B-Y OUT).

» Range : 10 mV/div. (AC) » Sweep time :10 µsec/div.

(Use a 10 : 1 probe.)

5. Adjust the sub-tint data to obtain the wavef orm as

shown in

6. Exit from the service mode.

Fig. 5

Fig.4

GMGR

About 3 Vp-p

Fig.5

ËË

A/V INPUT AND OUTPUT CHECK (1)

1. VIDEO and AUDIO OUTPUT CHECK

1. Receive the E-69CH.

(100% white colour bar, 400 Hz, 100% modulation audio)

2. Terminate the video output with a 75Ω impedance. Make sure the out-

put is as specified (1.0 Vp-p ± 3 dB(0.71 – 1.41 Vp-p).

3. Terminate the audio output with a 10k ohm impedance. Mak e sure the

output is as specified (2.6 Vp-p ± 3 dB(1.84 – 3.67 Vp-p). » Make sure the video and audio signals from the tuner are outputted.

2. VIDEO and AUDIO INPUT CHECK

1. Receive the E-69CH.

2. Feed the video and audio signal via the A/V input jacks.

3. Using the CH '/" keys on the remote controller, change to the AV

mode and make sure the external video and audio outputs are accordingly given. (The AV mode can be picked up between 1CH and 0CH.) CH ' 99 → 0 → AV1 → AV2 → 1 → 2 CH " 2 → 1 → AV2 → AV1 → 0 → 99 » The AV mode may also be picked up using the TV/VIDEO key on

the remote controller. RF → AV1 → AV2 → RF

WAVEFORM & OTHER 21PIN SCART

VIDEO OUT 19 PIN AUDIO OUT 1, 3 PIN

SC401(REAR)........AV1

WAVEFORM & OTHER

SC401(REAR)........AV1

J1401(FRONT).......AV2

ËË

A/V INPUT AND OUTPUT CHECK (2)

21PIN Euro-SCART (REAR)

37VT-26H(GY)

2468101214161820

121 35791113151719

1. Audio right output

2. Audio right input

3. Audio left output

4. Commom earth for audio

5. Earth for blue

6. Audio left input

7. Blue input

8. Audio-video control

9. Earth for green

10. Not used

11. Green input

12. Not used

13. Earth for red

14. Not used

15. Red input

16. Red/Green/Blue control

17. Earth for video

18. Earth for Red/Green/Blue control

19. Video output

20. Video input

21. Plug shield

Fig.6

ËË

PROTECTOR PERFORMANCE CHECK

1. BEAM PROTECTOR

1. Receive the monoscope pattern signal.

2. Set the contrast control to maximum.

3. Set the brightness control to maximum.

4. Make a short-circuit between the collector and emitter of Q1801 and

make sure that the protector is activated and the stand-by mode is called. (The POWER LED indicator starts flashing in red.)

2. HIGH-VOLTAGE PROTECTOR

1. Receive the monoscope pattern signal.

2. Connect the bias box to TP603.

3. Adjust the bias box voltage to 20 V and mak e sure that the protector is

not activated.

Note : Normally about 19 V

4. Adjust the bias box voltage to 25 V and mak e sure that the protector is

activated.

3. OTHER PROTECTORS

» In checking the performance of other protectors — for example, the

one against shorting of smoothing electrolytic capacitor of +B line —, pay attention not to damage or deteriorate any related element.

ËË

FUNCTION CHECK (1) (VIDEO AND AUDIO)

1. CONTRAST KEY

1. Receive the mono scope pattern signal.

2. Using the PICTURE ADJUST control, select CON-

TRAST .

3. The contrast must be changeable with the +/- ke y .

R/C

2. COLOUR KEY

1. Receive the PAL colour bar signal.

2. Using the PICTURE ADJUST control, select COL-

OUR.

3. The colour must be changeable with the +/- key.

(There must be no colour at the MIN position.)

3. BRIGHTNESS KEY

1. Receive the monoscope pattern signal.

2. Using the PICTURE ADJUST control, select

BRIGHT.

3. The black level must be changeable with the +/-

key.

MENU KEY

→PICTURE ADJUST

→CONTRAST →COLOUR →BRIGHT →TINT →V-TONE →WHITE TEMP →NORMAL

37VT-26H(GY)

ËË

FUNCTION CHECK (2) (VIDEO AND AUDIO)

4. TINT KEY

1. Receive the NTSC colour bar signal. (AV2 input)

2. Using the PICTURE ADJUST control, select TINT.

3. The tint must be changeable toward green with the + key and toward red with the - key.

5. PIC-NORMAL KEY

1. With the PICTURE ADJUST control, select NORMAL. Make sure the following normal settings are displayed.

Here are the normal settings.

» Contrast : 52 » Colour : CENTER (0) » Brightness : CENTER (0) » Tint : CENTER (0) » Sharpness : CENTER (0) » White T emp : CENTER (0)

6. WHITE TEMP KEY

1. Receive the monoscope pattern signal.

2. Using the PICTURE ADJUST control, select WHITE TEMP.

3. The BACK GND must be changeable with the +/- k ey with the + k ey (The w arm direction with the + key, the cold

direction with the - key ).

7. V-TONE KEY

1. Receive the monoscope pattern signal.

2. Using the PICTURE ADJUST control, select V-TONE.

3. The sharpness must be changeable with the +/- key.

8. CHANNEL SIGH DISPLAY COLOUR

1. The display colour of all the channel (0 ~ 99) signs must be green (AFT on).

9. COLOUR SYSTEM KEY

1. Input PAL COLOUR BAR with AV 1, 2. Using the

COLOUR SYSTEM key, select a mode other than AUT O/P AL and mak e sure the colour system does not work properly.

2. When receive the E-69CH. PAL COLOUR BAR,

make sure the colour system work properly.

3. When receive the JA-8CH NTSC 3.58 COLOUR

BAR, make sure the colour system does not work properly .

R/C

MENU KEY

→COLOUR SYSTEM (Selection is possible only at the time of the AV mode.)

PRECAUTIONS IN REASSEMBLING

INSTALLING THE CASSETTE CONTROLLER

When the cassette controller is installed on the mechanism, the initial setting is essential condition. There are two initial setting methods, namely electrical and mechanical.

1. Electrical initial setting

Make a short-circuit between TP7701 and TP7702 then plug in the AC cord and be sure that the mechanism is back to its initial setting position (*1). Now install the cassette controller in position. (Conditions: When mechanism and PWB have been installed)

Pulley feed gear

Screwdriver

37VT-26H(GY)

2. Mechanical initial setting

Feed the pulley feed gear of loading motor with screw driver. After ascertaining the return to the initial set position (*1) install the cassette controller in the specified position. (This method is applied only for the mechanism.)

Casecon drive gear

Tilt mark (*1)

INSTALLING THE MECHANISM ON PWB

Lower vertically the mechanism, paying attention to the mechanism edge, and install the mechanism with due care so that the parts are not damaged. So as to fix the mechanism to the main PWB tighten up the two screws. (One for fixing the mechanism and the head amplifier shield, the other on the main PWB's soldering side and located near the loading motor.) Connect again the FFC cable (AA-MH, AD-ME, AH-MZ) between the mechanism and the main PWB.

END SENSOR

REC TIP SW

Drive angle of cassette control

PARTS WHICH NEED PARTICULAR CARE

When installing the mechanism chassis on the PWB unit, take care so as to prevent deformation due to contact of mechanism chassis with Rec tip switch (S7701), Start sensor (Q7703) and End sensor (Q7704).

AE CONNECTOR

AC CONNECTOR

AL CONNECTOR

START SENSOR

37VT-26H(GY)

FUNCTION OF MAJOR MECHANICAL PARTS (TOP VIEW)

1715

No. Function

1 Full erase head 2 Supply pole base ass'y 3 Tension arm ass'y 4 Idler wheel ass’y 5 Pinch drive lever ass’y 6 Supply reel disk 7 Supply main brake ass'y 8 Take-up main brake ass'y 9 Pinch drive cam

10 A/C Head ass’y

No. Function

11 Reverse guide lever ass'y 12 Casecon drive gear 13 Take-up reel disk 14 Pinch roller lever ass’y 15 Drum ass'y 16 Loading motor 17 Drum motor 18 Take-up pole base ass'y 27 Fixing guide

37VT-26H(GY)

FUNCTION OF MAJOR MECHANICAL PARTS (BOTTOM VIEW)

19 20

No. Function

19 Slow brake lever 20 Master cam 21 Capstan D.D. motor 22 Reel belt

No. Function

23 Clutch lever 24 Limiter pulley ass'y

(12) Casecon drive gear

26 Shifter

37VT-26H(GY)

ADJUSTMENT, REPLACEMENT AND ASSEMBLY OF MECHANICAL UNITS

The explanation given below relates to the on-site general service (field service) but it does not relates to the adjustment and replacement which need high-grade equipment, jigs and skill. For example, the drum assembling, replacement and adjustment service must be performed by the person who have finished the technical courses.

Note :

There is a function to cut off the high voltage of TV by taking the plug of P2002 off the socket SC2002 in Main PWB in order to check only VCR part including mechanism. So you can use this function in the case of checking and adjusting mechanism.

1. MECHANISM CONFIRMATION ADJUSTMENT JIG

So as to perform completely the mechanism adjustment prepare the following special jigs. So as to maintain the initial performance of the machine the maintenance and check are necessary. Utmost care must be taken so that the tape is not damaged. If adjustment needs any jig, be sure to use the required jig.

No. Jig ltem Part No. Code Configuration Remarks

1. Torque Cassette Meter JiGVHT-063 CZ

JiGTG0090 CM

Torque Gauge

JiGTG1200 CN

3. Torque Gauge Head JiGTH0006 AW

4. Torque Driver JiGTD1200 CB

Master Plane Jig and Reel Disk Height

5. Adjusting Jig

JiGRH0002 BR JiGMP0001 BY JiGSG2000 BS

Tension Gauge6.

JiGSG0300 BF

Pinch pressing force

7. JiGADP003 BK measuring jig

Reverse guide height

8. adjustment box driver

JiGDRiVER11055

This cassette torque meter is used for checking and adjusting the torque of take-up for measuring tape back tension.

These Jigs are used for checking and adjusting the torque of take-up and supply reel disks.

When fixing any part to the threaded hole using resin with screw, use the jig. (Specified torque 5 kg)

These Jigs are used for checking and adjusting the reel disk height.

There are two gauges used for the tension measurements, 300 g and

2.0 kg. This Jig is used with the tension

gauge. Rotary transformer clearance adjusting jig.

This Jig is used for height adjustment of the reverse guide (for reverse guide height adjustment).

Alignment Tape9. VROCPSV CK

Guide roller height

10. JiGDRiVERH-4 AP

adjustment driver

X value adjustment

11. JiGDRiVER-6 BM

gear driver Reverse Guide Height

12. JiGRVGH-F18 BU

Adjusting Jig

Video Audio Track

625 Monoscope and Color Bar

This screwdriver is used for adjusting the guide roller height.

For X value adjustment

6kHz

and

1kHz

49µm

This Jig is used for height adjustment of the reverse guide.

2. MAINTENANCE CHECK ITEMS AND EXECUTION TIME

Perform the maintenance with the regular intervals as follows so as to maintain the quality of machine.

37VT-26H(GY)

Maintained

Parts

Guide roller ass’y Sup guide shaft Reverse guide Slant pole on pole base Full erase head A/C head

Upper and lower drum ass’y

Capstan D.D. motor Pinch roller

Reel belt

500 hrs.

1000 hrs.

1500 hrs.

2000 hrs.

Possible symptom

encountered

Lateral noises Head occasionally blocked

Colour and beating Small sound or sound

distortion Poor S/N ratio, no colour

Poor flatness of the envelope with alignment tape

No tape running, uneven colour

No tape running, tape slack

No tape running, tape slack, no fast forward/ rewind motion

Remarks

Abnormal rotation or significant vibration requires replacement.

Clean tape contact part with the specified cleaning liquid.

Clean tape contact area with the specified cleaning liquid.

Clean rubber and rubber contact area with the specified cleaning liquid.

Tension band ass’y Loading motor

Idler ass’y Limiter pulley Supply/take-up main brake levers

Screen swaying Cassette not loaded or

unloaded No tape running, tape

slack

Tape slack

Replace the roller of the cleaner

AHC (Automatic Head Cleaner)

when it wears down. Just change the AHC roller assembly for new one.

NOTE : Part replacement. : Cleaning : Apply grease <Specified> Cleaning liquid Industrial ethyl alcohol

* This mechanism does not need electric adjustment with variable resistor. Check parts. If any deviation is found,

clean or replace parts.

Video head cleaning procedure

1. Apply one drop of cleaning liquid to the cleaning paper with the baby oiler.

2. Gently press the cleaning paper against the video head to fix your finger, and move the upper drum so that each head is passed to and fro 5 times (do not move the cleaning paper).

3. Wipe with the dry cleaning paper.

Notes :

• Use the commercially available ethanol of Class 1 as cleaning liquid.

• Since the video head may be damaged, do not move up and down the cleaning paper.

Gently press the cleaning paper to fix with your finger, and rotate the upper drum to clean. Move to and fro 5 times for each head. (Do not move the cleaning paper.)

Rotate the upper drum with one hand.

• Whenever the video head is cleaned, replace the cleaning paper.

• Do not apply this procedure for the parts other than the video head.

Parts Code Description Code ZPAPRA56-001E Cleaning Paper AW ZOiLR-02-24TE Babe Oiler (Spoit) AH

37VT-26H(GY)

3.REMOVING AND INSTALLING THE CASSETTE HOUSING

• Removal

1. In the cassette eject mode, remove the cassette.

2. Unplug the power cord.

3. Remove in the following numerical order.

a) Remove two screws 1. b) Slide and pull up the cassette housing control.

Notes:

1. When fitting the S/E sensor holder to the cassette controller frame L/R, take care.

2. Misengagement of teeth of casecon drive gear and drive angle gear causes malfunction. (The cassette cannot be set, load and ejection are repeated).

3. In the case when you use the magnet screw driver, never approach the magnet driver to the A/C head, FE head, and drum.

4. When installing or removing, take care so that the cassette housing control and tool do not contact the guide pin or drum.

5. After installing the cassette housing control once perform cassette loading operation.

4.TO RUN A TAPE WITHOUT THE CASSETTE

HOUSING CONTROL ASSEMBLY

1. Short-circuit TP7701 (J930) and TP7702 (J359).

2. Plug in the power cord.

3. Turn off the power switch.

(The pole bases move into U.L.position.)

4. Open the lid of a cassette tape by hand.

5. Hold the lid with two pieces of vinyl tape.

6. Set the cassette tape in the mechanism chassis.

7. Stabilize the cassette tape with a weight (500g) to

prevent floating.

8. Turn on the power switch.

9. Perform running test.

Figure 1-1.

• Reassembly

1. Before installing the cassette housing control, shortcircuit TP7701 (J930) and TP7702 (J359) provided at the left of the main PWB, press the eject button. The casecon drive gear turns and stops when the positioning mark appears. Engage two teeth of casecon drive gear with the three teeth of casecon drive angle gear, and set on the mechanism chassis as shown below.

Casecon drive gear

Casecon drive angle gear

500g

Weight to prevent float (500g)

Mechanism chassis

Figure 1-3.

Note:

The weight should not be more than 500g.

• To take out the cassette tape.

1. Turn off the power switch.

2. Take out the cassette tape.

Figure 1-2.

2. Install in the reverse order of removal.

37VT-26H(GY)

5.REEL DISK REPLACEMENT AND HEIGHT

CHECK

• Removal

1. Remove the cassette housing control assembly.

2. Pull the tension band out of the tension arm ass'y.

3. Remove the Supply/Take-up main brake ass'y.

4. Open the hook at the top of the reel disk, and remove the reel disk.

Note:

Take care so that the tension band ass'y and main brake ass'y (especially soft brake) are not deformed.

Tension arm ass'y

Supply main brake ass'y

Tension band ass'y

Supply reel disk

Take-up main brake ass'y

Take-up reel disk

Notes:

1. When installing the reel disk, take due care so that the tension band ass'y is not deformed and grease does no adhere.

2. Do not damage the Supply main brake ass'y. Be careful so that grease does not adhere to the brake surface.

• Reassembly (Take-up reel disk)

1. Clean the reel disk shaft and apply grease (SC-141) to it.

2. Align the phase of the reel disk to that of the reel relay gear and to install a new take-up reel disk onto the shaft.

3. Check the reel disk height and reassemble the takeup main brake ass'y.

Notes:

1. Take care so that the Take-up main brake ass'y is not damaged. Take care so that grease does not adhere the brake surface.

2. After reassembly, check the video search rewind back tension (see 10.), and check the brake torque (see 14.).

• Height checking and adjustment

Notes:

1. Set the master plane with due care so that it does not contact the drum.

2. When putting the master plane, shift the reverse guide a little in the loading direction. Care must be taken since excessive shift results in damage.

Figure 1-4.

Note:

When the tension band ass'y is pressed in the direction of the arrow for removal, the catch is hard to be deformed.

Figure 1-5.

• Reassembly (Supply reel disk)

1. Clean the reel disk shaft and apply grease (SC-141) to it.

2. Match the phases of reel disk and reel relay gear, and set the new reel disk.

3. After checking the reel disk height, wind the tension band ass'y around the reel disk, and insert into the hole of tension arm ass'y.

4. Assemble the Supply main brake ass'y.

Master plane

Reverse guide

Supply reel disk

Cassette lock release shaft

Take-up reel disk

Position pin

Figure 1-6.

Note:

Check that the reel disk is lower than part A but higher than part B. If the height is not correct, readjust the reel disk height by changing the poly-slider washer under the reel disk.

37VT-26H(GY)

Note:

Whenever replacing the reel disk, perform the height checking and adjustment.

Master plane

10 ± 0.2mm

Reel disk

Reel disk height adjusting jig

Mechanism chassis

Figure 1-7.

6. CHECKING AND ADJUSTMENT OF TAKE-UP

TORQUE IN FAST FORWARD MODE

• Remove the cassette housing control assembly.

• After short-circuiting TP7701 (J930) and TP7702 (J359) provided at the left on the main PWB, plug in the power cord, then turn on the power.

• Setting

1. Set a torque gauge to zero on the scale. Place it on the take-up reel disk.

2. Press the FF button.

3. To calculate the remaining capacity of the play back mode, slowly rotate the supply reel disk, and then shift it into the forward mode.

Notes:

1. Hold the torque gauge by hand so that it is not moved.

2. Do not keep the reel disk in lock state. Do not allow long-time measurement.

7. CHECKING AND ADJUSTMENT OF TAKE-

UP TORQUE IN REWIND MODE

• Remove the cassette housing control assembly.

• After short-circuiting TP7701 (J930) and TP7702 (J359) provided at the left on the main PWB, plug in the power cord, then turn on the power.

• Setting

1. Set a torque gauge to zero on the scale. Place it on the supply reel disk.

2. Press the rewind button.

3. To calculate the remaining capacity, slowly rotate the take-up reel disk, and then shift it into the rewind mode.

• Checking

1. Turn the torque gauge slowly (one rotation every 2 to 3 seconds) by hand in the CCW direction.

2. Make sure that the indication of torque gauge is not less than 30mN·m (306gf·cm).

Torque gauge

• Checking

1. Turn the torque gauge slowly (one rotation every 2 to 3 seconds) by hand in the CW direction.

2. Make sure that the indication of torque gauge is not less than 30mN·m (306gf·cm).

Torque gauge

30mN·m (306gf·cm) or more

Idler ass'y

The gauge is held at its maximum value. (Red mark)

Figure 1-8.

• Adjustment

1. If the FF winding-up torque is less than the specified value, clean the capstan D.D. motor pulley, reel belt, and limiter pulley with cleaning liquid, and check again.

2. If the torque is less than the set value, replace the reel belt.

30mN·m (306gf·cm) or more

CCW

The gauge is held at its maximum value. (Red mark)

Supply reel disk

Idler ass'y

Figure 1-9.

• Adjustment

1. If the rewind winding-up torque is less than the specified value, clean the capstan D.D. motor pulley, drive belt, and limiter pulley with cleaning liquid, rewind again, and check the winding-up torque.

2. If the winding-up torque is still out of range, replace the drive belt.

Notes:

1. Hold the torque gauge by hand so that it is not moved.

2. Do not keep the reel disk in lock state. Do not allow long-time measurement.

37VT-26H(GY)

8.CHECKING AND ADJUSTMENT OF TAKEUP TORQUE IN RECORD/PLAYBACK MODE

• Remove the cassette housing control assembly.

• After short-circuiting TP7701 (J930) and TP7702

(J359) provided at the left on the main PWB, plug in the power cord.

• Turn off the power switch.

• Open the cassette torque meter lid, and fix it with

tape.

• Load the cassette torque meter into the unit.

• Put the weight (500g) on the cassette torque

meter.

• Turn on the power switch.

• Press the REC button, and set LP picture record

mode.

Set value LP6.9 ± 2.5mN⋅m (70 ± 25gf⋅cm)

500g

9.CHECKING AND ADJUSTMENT OF TAKEUP TORQUE IN VIDEO SEARCH REWIND MODE

• Remove the cassette housing control assembly.

• After short-circuiting TP7701 (J930) and TP7702

(J359) provided at the left on the main PWB, plug in the power cord, then turn on the power.

• Setting

1. Press the playback button and rewind button to set

the video search rewinding mode.

• Checking

1. Place the torque gauge on the supply reel disk, and

turn it counterclockwise very slowly (one rotation every 1 to 2 seconds) and check that the torque is within the set value 14.0 ± 3.9mN⋅m. (144 ± 40gf⋅cm)

Torque gauge

CCW

Cassette torque meter

Figure 1-10.

• Checking

1. Make sure that value is within the setting 6.9±2.5mN·m (70±25gf·cm).

2. The winding-up torque fluctuates due to variation of rotation torque of limiter pulley ass'y. Read the center value of fluctuation as setting.

3. Set the LP record mode and make sure that the winding-up torque is within setting.

• Adjustment

1. If the playback winding-up torque is not within the setting, replace the limiter pulley assembly.

Note:

When the torque cassette is set, put a weight (500g) to prevent rise. When the cassette torque meter is taken out, turn off the power switch.

Supply reel disk

Figure 1-11.

Note:

Surely put the torque gauge on the reel disk to measure. If the torque gauge is raised, accurate measurement is impossible.

• Adjustment

1. If the rewinding playback winding-up torque is not within the setting, replace the limiter pulley assembly.

Note:

The winding-up torque fluctuates due to variation of rotation torque of supply reel disk. Read the center value of fluctuation as setting.

37VT-26H(GY)

10.CHECKING THE VIDEO SEARCH REWIND BACK TENSION

• Remove the cassette housing control assembly.

• After short-circuiting TP7701 (J930) and TP7702

(J359) provided at the left on the main PWB, plug in the power cord, then turn on the power.

• Checking

1. After pressing the play button, press the rewind

button, and set the video search rewind mode.

2. Place the torque gauge on the take-up reel disk, and

turn it counterclockwise very slowly (one rotation every 2 to 3 seconds) and check that the torque is within the set value 3.4±1.5mN⋅m (35±15gf⋅cm).

Torque gauge

CCW

Take-up reel disk

Figure 1-12.

Note:

Set the torque gauge securely on the take-up reel disk. If it is not secure, the measurement will be incorrect.

11. CHECKING THE PINCH ROLLER PRESSURE

• Remove the cassette housing control assembly.

• After short-circuiting TP7701 (J930) and TP7702

(J359) provided at the left on the main PWB, plug in the power cord, then turn on the power.

Pinch roller

Capstan shaft

Tension gauge adapter

Tension gauge

8.8 –11.8N (900 ~ 1,200gf)

Figure 1-13.

1. Detach the pinch roller from the capstan shaft. Do not separate excessively. Or the pinch lever and pinch double action lever may disengage.

2. Engage the tension gauge adapter with the pinch roller shaft, and pull in the arrow direction.

3. Gradually return the pinch roller, and measure the pulling force when the pinch roller contacts the capstan shaft.

4. Make sure that the measured value is within setting

8.8 to 11.8 N (900 to 1,200gf).

12. CHECKING AND ADJUSTMENT OF

TENSION POLE POSITION

• Remove the cassette housing control assembly.

• After short-circuiting TP7701 (J930) and TP7702 (J359) provided at the left on the main PWB, plug in the power cord.

• Setting

1. Turn off the power switch.

2. Open the cassette tape (E-180), and fix with tape.

3. Set the cassette tape in loading state.

4. Put the weight (500g) on the cassette tape.

5. Turn on the power switch.

6. Make the adjustment with the beginning of a E-180 tape.

(E-180)

• Checking

1. Press the play button to set the playback mode.

500g

Weight to prevent float (500g)

Figure 1-14.

37VT-26H(GY)

• Checking

1. Set a cassette tape, push the REC button to place the unit in the SP record mode. Now check the tension pole position.

2. Visually check to see if the right edge of the tension pole is within the 2.3 ± 0.25mm from the right edge of the Sup guide shaft.

Supply guide shaft

Tension pole

2.3 ± 0.25mm

Make the adjustment with the beginning of a E-180 tape.

Figure 1-15.

At left side from the center line

Tension pole adjuster adjusting range

Tension pole adjuster

90°

Figure 1-18.

Adjust so that the delta mark of tension pole adjuster is within 90° range (left, right).

13. CHECKING AND ADJUSTMENT OF RECORD/PLAYBACK BACK TENSION

• Remove the cassette housing control assembly.

2.3 ± 0.25mm

Figure 1-16.

Insert the slotted screwdriver in the tension pole adjuster, and rotate counterclockwise.

At right side from the center line

2.3 ± 0.25mm

Figure 1-17.

Insert the slotted screwdriver in the tension pole adjuster, and rotate clockwise.

• After short-circuiting TP7701 (J930) and TP7702

(J359) provided at the left on the main PWB, plug in the power cord.

• Setting

1. Turn off the power switch.

2. Open the torque cassette meter and fix with tape.

3. Set the cassette tape in loading state.

4. Put the weight (500g) on the cassette torque meter.

5. Turn on the power switch.

500g

Weight to prevent float (500g)

Cassette torque meter

Figure 1-19.

• Checking

1. Push the REC button to place the unit in the SP

record mode.

2. At this time ascertain that the back tension is within

the setting (36.5 to 52g·cm) by seeing the indication of torque cassette meter.

37VT-26H(GY)

• Adjustment

1. If the indication of torque cassette meter is lower than the setting, shift the tension spring engagement to the part A.

2. If the indication of torque cassette meter is higher than the setting, shift the tension spring engagement to the part B.

Tension arm

Tension spring

Figure 1-20.

14. CHECKING THE BRAKE TORQUE

• Checking the brake torque at the supply side

Torque gauge

CCW

• Checking the brake torque at the take-up side

Torque gauge

Take-up reel disk

CCW: 8.8~23.5mN⋅m (90~240gf⋅cm) CW: 4.9~11.8mN⋅m (50~120gf⋅cm)

CCW

Figure 1-22.

• Remove the cassette housing control assembly.

• After short-circuiting TP7701 (J930) and TP7702 (J359) provided at the left on the main PWB, plug in the power cord, then turn on the power.

Supply reel disk

CCW: 3.9~9.8mN⋅m (40~100gf⋅cm) CW: 8.8~23.5mN⋅m (90~240gf⋅cm)

Figure 1-21.

• Remove the cassette housing control assembly.

• After short-circuiting TP7701 (J930) and TP7702 (J359) provided at the left on the main PWB, plug in the power cord, then turn on the power.

• Setting

1. Set a torque gauge to zero on the scale. Place it on the supply reel disk.

2. Switch from the FF mode to the STOP mode.

3. Disconnect the power cord.

• Checking

Turn the torque gauge at a rate of about one turn/2 sec in the CW direction/CCW direction with respect to the supply reel disk so that the reel disk and torque gauge pointer rotate at equal speed, and make sure that the value is within the setting (CW direction: 8.8 to 23.5mN·m (90 to 240gf·cm); CCW direction: 3.9 to

9.8mN·m (40 to 100gf·cm).

• Setting

1. Switch from the FF mode to the STOP mode.

2. Disconnect the power cord.

3. Set a torque gauge to zero on the scale. Place it on the take-up reel disk.

• Checking

1. Turn the torque gauge at a rate of about one turn/2 sec in the CCW direction/CW direction so that the reel disk and torque gauge pointer rotates at equal speed and make sure that the value is within the setting (CCW direction: 8.8 to 23.5mN·m (90 to 240gf·cm), CW direction: 4.9 to 11.8 mN·m (50 to 120gf·cm).

2. Adjustment of the brake torque at the supply side and the take-up side

• Unless the supply side brake torque or take-up side brake torque is within the setting, clean the felt surface of reel disk (supply, take-up) brake lever, check again the brake torque.

• If value cannot be set within the setting yet, replace the main brake ass'y or main brake spring.

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