Tandberg TD 20 A Service Manual

Page 2

Contents

Page

General ....................................................................... 3

Dismantling the cabinet ......................................................... 3

Removing the black top cover .................................................... 3

Replacing the black top cover ................................................. 3

Removing the meter panel. . 4-

Replacing the meter panel. . 4
Mechanical checks and adjustments .................................................. 4

Checking the braking force ...................................................... 4-

Adjusting the braking force . . 5

Checking the pinch roller pressure ................................................. 5

Tape tension arms .....................

Changing the drive belt . . .......

Adjusting the thrustvbearing for the capstan .....

Changing the tapeeuountcr belt ...............

Changing the worm-gear motor. ..........

Changing the capstan motor i

Changing the reel motor ......................

Changing and adjusting the micvoswitch ............................................ l 1
Maintenance ................................................................... I 2

Cleaning the tape path .......................................................... 12

Degaussing ................................................................... l2

Lubrication .................................................................. l 2
Tape path adjustments and head adjustment ........................................... 13

Adjusting the tape path ......................................................... 13

Adjusting the parallelismt .............

Left tape tension arm . . . .............

'Iapc guide posts . . . .............

Pinch roller . . iiiii r . iiiiiiiiiii

Checking and ref justing the flutter rollcr ........

Head alignment with 'lantlbcrg test tapes, [our track .................................. )6

Head alignment without 'l'andberg tcst tapes, four track ................................ 17

Head alignment, two track ...................................................... 18
Record and playback curves, NAB .................................................. 19
Checking the record and playback curves, [EC ......................................... 20

Fault in the total response curve, one channel. . .

38 kHz filter in record amplifiers .........

PLOT/BOT sensor (end of tape/beginning of tap

Power On/Off circuit ......................

'l'MI sensor (tape motion indicator) ...........

Control circuit for reel motors ............

Wormegear motor ............................................................. 25
Logic Circuits .................................................................. 26

The a-synchmnous logic circuit ................................................... 27

The PROM control unit ......................................................... 27
Electrical adjustments ............................................................ 28
Circuit diagrams and PC. boards .................................................... 30