BASIC SERVICE TECHNICAL INFORMATION Real Time Video Cassette Recorder Contents 1. MAINTAINING AND CHECKING THE MECHANISM 1-1. REGULAR CHECKS AND MAINTENANCE ITEMS ... 2 1-2. SERVICE TOOLS AND CLEANING ... 3 2. AN OVERVIEW OF THE MECHANISM 2-1. NAMES OF THE MAIN PARTS ... 4 2-2.
1. MAINTAINING AND CHECKING THE MECHANISM 1-1. REGULAR CHECKS AND MAINTENANCE ITEMS To obtain full function and maximum performance from the set, and to stop it getting dirty or scratched, we recommend that you carry out the following mainte- nance procedures and regular checks. The maintenance checks described in the following section should also be carried out without fail after carrying out any repairs to the set.
VHJ-0008 SP colour bar 1kHz (normal) SP monoscope 7kHz or 6kHz (normal) VHJ-0009 SP sync signal 400Hz/7kHz (D-VCR) [DN-S704M] LEP sync signal (D-VCR) [DN-LE0] Used to adjust the tape path Used to adjust the height of the lever load assembly...
1-2-2. CLEANING 1. Cylinder (Drum) (See Fig.1-2-2) Moisten a chamois with methyl alcohol and clean the video head and the tape path surface of the cylinder. Be sure to wipe horizontally in relation to the video head. If you wipe vertically, or use excessive force, you can damage the video head.
Page 5
2-1-2. TOPVIEW Cylinder (Drum) Cylinder mounting Guide roller assembly T incline mounting assembly Full erase head S incline mounting assembly Guide roller assembly Tape end sensor BT lever assembly Tape sensor LED BT spring Band brake assembly Supply reel assembly S soft lever EP switch EP sw lever...
2-2. AN OVERVIEW OF THE MECHANISM MODES 2-2-1. MECHANISM MODE SWITCHING TABLE NOTE : The letters and figures enclosed in circles in the mechanism mode column are the codes on the crescent slide. Mechanism mode DATA EJECT Distinguished by whether the EP switch is ON or OFF.
Page 7
2-2-2. MOVEMENT CHECK LIST FOR THE MAIN PARTS OF THE MECHANISM Mechanism mode Principal parts T brake assembly S brake assembly T soft brake assembly S soft lever BT lever assembly BT spring Pinch roller lever assembly Clutch mounting assembly Load lever assembly Capstan brake assembly S and T incline mounting assembly...
3. DISASSEMBLING THE MAIN PARTS OF THE MECHANISM POINTS TO NOTE • When fitting the parts of the mechanism, refer to the "Assembly Notes", and proceed in the reverse of dis- assembly order. • Dis-assembly and assembly should be carried out in EJECT mode unless a movement mode is explicitly specified.
Screw 3-3. CASSETTE DRIVE MECHANISM 3-3-1.CASSETTE MECHANISM ASSEMBLY (See Figs.3-3-1 and 3-3-2) 1) Put the VCR into EJECT mode. 2) Remove the two screws 3) Lift up the back of the cassette mechanism assembly slightly, and remove the two hooks...
Page 10
3-3-2. CASSETTE DRIVE GEAR (See Fig.3-3-3) 1) Refer to section 3-3-1 and remove the cassette mecha- nism assembly. 2) Remove clamps , then remove the gear holder 3) Remove the clamp , then remove the pinion gear 4) Remove the clamp , then remove the lock gear ASSEMBLY NOTES: 1.
3-3-4.START RACK GEAR AND FRONT RACK GEAR (See Figs.3-3-5 and 3-3-6) 1) Remove the mechanism unit, referring to section 3-2. 2) Remove the cassette mechanism assembly, referring to section 3-3-1. 3) Remove the special screw . When you do this, slide the front rack gear assembly it stops, then take it off the shaft damage the shaft...
3-5. CYLINDER (DRUM) 3-5-1. UPPER CYLINDER ASSEMBLY (UPPER DRUM) (See Figs. 3-5-1, 3-5-2, 3-5-3,3-5-4) 1) Remove the two screws (See Fig.3-5-1). 2) First, tighten the handle removing tool (VHJ-0041), then screw the two long screws evenly into the two screw holes upper cylinder assembly (upper drum) 3-5-2).
Page 13
3-5-2. CYLINDER (DRUM) UNIT (See Fig.3-5-5) 1) Put the mechanism into EJECT mode. 2) Refer to section 3-2 and remove the VM-1/VP-1 PWB assembly 3) Refer to section 3-4 and remove the cleaner lever. 4) Remove the three screws scratch or soil the tape path surface of the cylinder (drum), lift the cylinder mounting ing it raised.
3-5-4. CYLINDER ASSEMBLY (See Fig.3-5-7) 1) Refer to sections 3-5-2 and 3-5-3, and remove the cylinder unit, the rotor, and the stator. 2) Remove the three screws assembly ASSEMBLY NOTES: 1. Be careful not to scratch or soil the top of the cylinder. After fitting the cylinder, clean the surface.
3-7. CAPSTAN MOTOR 3-7-1. CAPSTAN MOTOR (See Fig. 3-7-1) 1) Refer to section 3-2, then remove the mechanism unit. 2) Remove the reel belt 3) Remove the three screws and the capstan motor 4) Remove the heat transfer spacer motor or mechanism chassis.
3-8. LOADING MOTOR ASSEMBLY AND WORM GEAR ASSEMBLY (See Fig.3-8-1) 1) Refer to section 3-2 and remove the mechanism unit. 2) Remove the soldering on the lead wires loading motor assembly from the MC-1 PWB as- sembly. When you do this, be careful not to let the soldering iron touch any other parts.
Page 17
3-9-2.PINCH LIFT CAM AND PINCH CAM GEAR (See Figs.3-9-2 and 3-9-3) 1) Refer to section 3-2 and remove the mechanism unit. When you do this, make sure the mechanism is in EJECT mode. 2) Refer to section 3-9-1 and remove the pinch roller lever assembly.
3-10. L GUIDE ACT LEVER ASSEMBLY, LOAD LEVER ASSEMBLY AND STOPPER LEVER ASSEMBLY (See Fig.3-10-1) 1) Refer to section 3-3 and remove the cassette mecha- nism assembly. 2) Refer to sections 3-9-1 and 3-9-2 ,then remove the pinch roller lever assembly and the opener mount- ing.
3-12. REEL DRIVE MECHANISM 3-12-1.REEL BELT, REEL PULLEY, FRICTION GEAR ASSEMBLY AND CLUTCH CHANGE LEVER (See Fig.3-12-1) Refer to section 3-2 and remove the mechanism unit. Remove the reel belt from the reel pulley Take off the washer and remove the reel pulley Take off the washer and remove the friction gear assembly...
3-12-4.T SOFT BRAKE ASSEMBLY, TAKE UP REEL ASSEMBLY, T REEL GEAR (See Fig.3-12-4) 1) Remove the T soft spring 2) Remove the clamp , then remove the T soft brake assembly 3) Refer to section 3-12-2 and remove the clutch mount- ing assembly.
Page 21
3-13-2.BRAKE CONTROL LEVER AND BRAKE ACT LEVER ASSEMBLY (See Fig.3-13-2) 1) Refer to section 3-2 and remove the mechanism unit. 2) Refer to section 3-15 and remove the wheel gear 2. 3) Refer to sections 3-12-1, then remove the reel belt and the reel pulley.
3-14. GUIDES 3-14-1. GUIDE ROLLER ASSEMBLY (See Fig.3-14-1) 1) Unscrew the two screws . When you do this, be careful not to damage the cylinder or the video head. 2) Remove the two guide roller assemblies screwing them counterclockwise. ASSEMBLY NOTES: 1.
3-15. WHEEL GEAR 2, MAIN CAM AND MODE SWITCH (See Figs.3-15-1 and 3-15-2) 1) Refer to section 3-2 and remove the mechanism unit. When you do this, make sure the mechanism is in EJECT mode. 2) Remove the clamp , then remove the wheel gear 2 3) Remove the washer , then remove the main cam 4) After unscrewing the screw...
3-16. CRESCENT SLIDE (See Figs.3-16-1 and 3-16-2) 1) Refer to section 3-2 and remove the mechanism unit. When you do this, make sure the mechanism is in EJECT mode. 2) Refer to section 3-3-1 and remove the cassette mecha- nism assembly. 3) Refer to section 3-7-2 and remove the capstan brake assembly.
3-17. S LOAD GEAR, T LOAD GEAR, S LOAD LEVER ASSEMBLY AND T LOAD LEVER ASSEMBLY (See Figs.3-17-1, 3-17-2 and 3-17-3) 1) Refer to section 3-16 and remove the crescent slide. 2) Refer to section 3-14-2 and remove the S and T incline mounting assemblies.
3-18. TAPE SENSORS, REEL SENSOR AND EP SW LEVER 3-18-1 TAPE TOP SENSOR AND TAPE END SENSOR (See Fig.3-18-1) 1) Refer to section 3-2 and remove the mechanism unit. 2) Refer to section 3-3-1 and remove the cassette mechanism assembly. 3) Remove the soldering from the MC-1 PWB assembly, then remove the photo diodes .
4. MECHANISM CHECKS AND ADJUSTMENTS 4-1. REEL TABLE TORQUE CHECK 1)With the power switch turned OFF, stick black vinyl tape over the photo diodes of the tape sensors. Then turn the power switch ON. Front loading will begin. Refer to section 3-2 and Fig.3-2-2, and release the locks of the tray lock lever and the lid opener lever.
4-3. TAPE PATH ADJUSTMENT In normal circumstances, the tape path system does not need to be adjusted. However, after removing or replac- ing one of the parts shown in Fig.4-3-1, you should check and adjust the tape path. The adjustment of the tape path is carried out while monitoring the envelope waveform of the video head output, using an oscilloscope.
Page 29
4-3-3.GUIDE ROLLER HEIGHT ADJUSTMENT (See Figs.4-3-3 and 4-3-4) 1) Playback the Alignment Tape (VHJ-0118) and check that the envelope waveform is at its maximum at the tracking centre. Then, after loosening the S guide roller and the T guide roller by rotating them counterclockwise, tighten them in turn until the enve- lope waveform becomes flat.
Page 30
4-3-4. AUDIO R/P HEAD (ACE HEAD) HEIGHT ADJUSTMENT, AZIMUTH ADJUSTMENT AND HORIZONTAL POSITION ADJUSTMENT NOTE: For the audio output waveform, observe the analog wave- form. Connect the oscilloscope appropriately according to CP-1 BOARD (AD-A) ACE HEAD ADJUSTMENT in the Circuit Diagram Part. For DTL-4800, DTL-4800P, the CN308 pin on the CP-1 board is the test point.
Page 31
4-3-5. CHECKING AFTER ADJUSTMENT 1) Play the alignment tape (VHJ-0119) and check that the envelope waveform is activated immediately and that there are no fluctuations in the envelope wave- form. 2) Load a cassette tape (ST-180) and use it to record and replay.
Page 32
SANYO Electric Co., Ltd. Osaka, Japan Sep/'00/2300 SU...