AG-TL750E, AG-TL750B - Panasonic Provideo Service Manual (repair manual). Page 3

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SAFETY PRECAUTIONS........................................................5

1.1 DISASSEMBLY OF MAJOR PARTS.............................1-1

1.1.1 Disassembly Flow Chart ........................................1-1
1.1.2 Replacing the Fuse................................................1-1
1.1.3 Removing the Top Cover.......................................1-1
1.1.4 Removing the Front Panel Assembly.....................1-1
1.1.5 Removing the Bottom Cover..................................1-2
1.1.6 Removing the Cassette Housing Assembly ...........1-2
1.1.7 Removing the Mechanism Assembly.....................1-2

1.2 DIAGNOSTICS OF MAJOR PC BOARDS ....................1-3

1.2.1 Diagnosing the MAIN and DECK TERMINAL

Boards ................................................................1-3

1.2.2 Diagnosing the FRONT 1 and FRONT 2 Boards ...1-3
1.2.3 Diagnosing the SW REG. Board............................1-3
1.2.4 Diagnosing the P/R Board .....................................1-4
1.2.5 Replacing the Lithium Battery................................1-4

1.3 SERVICE MENU...........................................................1-5

1.3.1 Menu Configuration and Operation Procedure.......1-5
1.3.2 Function ................................................................1-6
1.3.3 Hour meter ............................................................1-6
1.3.4 Emergency history.................................................1-6
1.3.5 Mecha check mode ...............................................1-8

1.4 LITHIUM BACKUP BATTERY.......................................1-10

1.4.1 Battery Replacement Caution ................................1-10
1.4.2 Time/Date Backup.................................................1-10

1.5 EEPROM ......................................................................1-10
1.6 CIRCUIT PROTECTORS..............................................1-10
1.7 RESETTING THE MICROCOMPUTER

IN CASE OF A RUNAWAY........................................1-10

2.1 BEFORE MAKING REPAIR/ADJUSTMENT .................2-1

2.1.1 Precautions ...........................................................2-1
2.1.2 How to unload the cassette tape manually ............2-1
2.1.3 Special tools Required for Adjustment ...................2-1
2.1.4 Specifications of alignment tape ............................2-1

2.2 MAINTENANCE AND CHECK ......................................2-2

2.2.1 Location of main mechanical parts ........................2-2
2.2.2 Maintenance of main parts and periodical

reference ............................................................2-3

2.2.3 Cleaning ................................................................2-4
2.2.4 Lubrication.............................................................2-4

2.3 REPLACEMENT OF MAIN PARTS...............................2-4

2.3.1 Before removing ....................................................2-4
2.3.2 How to set to the mechanism assembly position ...2-4
2.3.3 Upper drum assembly ...........................................2-4
2.3.4 Brush assembly.....................................................2-5
2.3.5 Cleaner roller assembly .........................................2-5
2.3.6 Pinch roller arm assembly .....................................2-5
2.3.7 Tension band assembly.........................................2-5
2.3.8 Capstan motor, Capstan brake arm assembly.......2-6
2.3.9 Drum assembly .....................................................2-6
2.3.10 Clutch unit (S, T), Control plate, Reel disk (S, T) .2-7
2.3.11 Full-erase head....................................................2-9
2.3.12 A/C head assembly .............................................2-9
2.3.13 Belt (Loading) ......................................................2-9
2.3.14 Belt (Capstan, Housing).......................................2-10
2.3.15 Idler assembly .....................................................2-10
2.3.16 Sub brake assembly (T).......................................2-10
2.3.17 Sub brake assembly (S) ......................................2-10
2.3.18 Pole base assembly (S, T)...................................2-11
2.3.19 Guide flange (S, T) ..............................................2-11
2.3.20 Guide arm assembly............................................2-12
2.3.21 Loading motor, Motor pulley ................................2-12
2.3.22 Rotary encoder, Control cam ...............................2-12
2.3.23 Slide plate, Main brake assembly (S, T) ..............2-13
2.3.24 Slit disk (S, T) ......................................................2-14
2.3.25 Guide rail, Loading arm assembly (S, T)..............2-14
2.3.26 Pulley assembly ..................................................2-15
2.3.27 Worm gear assembly ..........................................2-16

2.4 HOW TO MOUNT THE MAIN PARTS

(Mechanism Phase Adjustment) ................................2-16

2.4.1 Before parts assembling ........................................2-16
2.4.2 Loading arm assembly (S, T).................................2-16
2.4.3 Rotary encoder, Change lever, Control cam ..........2-17
2.4.4 Slide plate..............................................................2-17
2.4.5 Control plate ..........................................................2-17

2.5 INTERCHANGEABILITY ADJUSTMENT ......................2-18

2.5.1 FM waveform linearity check/adjustment ...............2-18
2.5.2 A/C head assembly height, Azimuth

check/adjustment................................................2-19

2.5.3 A/C (Audio Control) head

phase (X value) check/adjustment ......................2-20

2.5.4 Tension arm position check/adjustment.................2-21
2.5.5 Take-up torque check ............................................2-21
2.5.6 Tape transport system check/adjustment ..............2-21

3.1 PRECAUTIONS BEFORE PROCEEDING

TO ELECTRICAL ADJUSTMENTS............................3-1

3.2 EQUIPMENT REQUIRED FOR

ELECTRICAL ADJUSTMENTS .................................3-1

3.2.1 Measuring Instruments Required for Adjustments .3-1
3.2.2 Tools to be Prepared .............................................3-1
3.2.3 Signals Required for Adjustments..........................3-1

3.3 SERVICE MODES USED IN ADJUSTMENTS..............3-1

3.3.1 SERVO ADJUST MODE Setting Method...............3-1
3.3.2 EVR ADJUST MODE Setting Method....................3-1

3.4 SERVO ADJUSTMENTS ..............................................3-2
3.5 VIDEO ADJUSTMENTS................................................3-4

4.1 OVERALL WIRING DIAGRAMS ...................................4-3
4.2 SYSCON/SERVO BLOCK DIAGRAM ...........................4-4
4.3 VIDEO BLOCK DIAGRAM ............................................4-5
4.4 AUDIO BLOCK DIAGRAM ............................................4-6
4.5 MAIN BOARD SCHEMATIC DIAGRAMS......................4-7

4.5.1 SYSCON/SERVO..................................................4-7
4.5.2 VIDEO (1/3)...........................................................4-8
4.5.3 VIDEO (2/3)...........................................................4-9
4.5.4 VIDEO (3/3)...........................................................4-10
4.5.5 AUDIO ...................................................................4-11
4.5.6 REGULATOR ........................................................4-12

4.6 MAIN/COME MIX CIRCUIT BOARDS ...........................4-13
4.7 DECK TERMINAL BOARD SCHEMATIC DIAGRAM ....4-14
4.8 DECK TERMINAL CIRCUIT BOARD ............................4-15
4.9 FRONT1,2 BOARD SCHEMATIC DIAGRAM................4-16
4.10 FRONT1 CIRCUIT BOARD.........................................4-17
4.11 FRONT2 CIRCUIT BOARD.........................................4-17
4.12 SW REG. BOARD SCHEMATIC DIAGRAM ...............4-18
4.13 SW REG. CIRCUIT BOARD .......................................4-19
4.14 P/R BOARD SCHEMATIC DIAGRAMS.......................4-20

4.14.1 VIDEO .................................................................4-20
4.14.2 AUDIO .................................................................4-21

4.15 P/R CIRCUIT BOARD .................................................4-22
4.16 CONNECT BOARD SCHEMATIC DIAGRAM..............4-23
4.17 CONNECT CIRCUIT BOARD .....................................4-23
4.18 SENSOR BOARD SCHEMATIC DIAGRAM ................4-23
4.19 SENSOR CIRCUIT BOARD ........................................4-23

5.1 CABINET & CHASSIS ASSEMBLY ..............................5-2
5.2 MECHANISM ASSEMBLY ............................................5-4
5.3 PACKING ASSEMBLY..................................................5-6

ELECTRICAL REPLACEMENT PARTS LIST..........................5-8