Tascam 122 Service Manual

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. TASCAM

TEAC Production Products

SERVICE MANUAL

122

MASTER CASSETTE DECK

Effective: April. 1981 310041

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122

TABLE OF CONTENTS

1. Specifications ..................... 3 6-4. Capstan assembly thrust ......... 44
2. Features and controls 6.5. Takeup torque ................ 44
2-1. Front panel features and controls . . 4 66. Fast forward and rewind torque . . . 44
2-2. Rear panel connections ......... 5 6-7. Pinch roller pressure ............ 44
3. Circuit description 6-8. Tape speed ................... 45
Control section 6-9. Wow and flutter ............... 45
3-1. System control IC ............. 6 7. Record/reproduce amplifier checks and
3-2. System control IC input/output adjustments
circuits . _. .................... 9 7-1. Reproduce output level setting . . . . 47
3-3. Solenoid drive circuit ........... 10 7-2. VU meter setting .............. 47
3-4. Reel motor drive circuit ......... 15 7-3. Reproduce frequency response . . . . 47
35. Capstan motor circuit ........... 18 7-4. Bias setting adjustment .......... 48
3-6. Tape-end detection circuit ....... 18 75. Record level .................. 48
3-7. Memory circuit ................ 20 7-6. Overall frequency response ....... 48
3.8, Power supply circuits ....... ', . _ _ 20 77. Overall signal-to-noise ratio ...... 49
3.9 Overall operation of the deck _____ 24 7-8. Overall distortion .............. 49
3 10. Muting circuits ................ 26 7- 9 Erasure ...................... 49
Amplifier section 7-10. Channel separation ............. 50
3-11. Reproduce circuit .............. 30 7 11- LED lighting 0f VU' meter (PEAK
3412. Monitor circuit ................ 32 indicator) .................... 50
3-13. Record circuits ................ 34 742- DOIbY NOiSE Reduction Effec'f - - - - 50
3-14. Dolby HX circuit .............. 37 743- DOibY HX Eff? --------------- 50
4. Parts location ..................... 41 7-14. Headphones output level ........ 51
5. Essential maintenance 7-15. Bias trap adjustment ............ 51
equipment/material ................ 42 7-16. BIAS/REC calibration check ..... 51
6. Electra-mechanical checks and adjustments 8. Exploded views and parts lists ........ 52
6-1. Head base plate positioning ...... 43 9. PC boards and parts lists ............. 58
6-2. Microswitch (A) assembly 10. Semiconductors lists ................ 67
clearance .................... 43 11. Assembling hardware coding lists ...... 68
6-3. Microswitch (B) assembly 12. Block-diagram .................... 69
clearance .................... 43
NOTES: 1. in the diagram of each PC board, its pattern surface is shown.
2. With certain exceptions, the reference numbers in the 100s, 300's
and 700s refer to the Lch, and those in the 200's, 400s and 800's
to the Rch.
3. Parts marked with A are safety critical components.
They must always be replaced with components specified by TEAC.
4. Service data are found where they are necessary.
Improvements may result in service data changes without notice.
0 Dolby Noise Reduction. System manufactured under license from Dolby
Laboratories Licensing Corporation.
0 Dolby and the double-D symbol are trademarks of Dolby Laboratories
Licensing Corporation.
48me 119) 345mm (13 - 5/8")
0 + o [ $5)
El 1: o e .-
P o / /_ :1 El a a o i E g a Q
Do (Moots: a: a , ,
o o D D + o a a Q ~03 s)

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