Operating instructions

October 1990
6 - 1
Section 6 Alignment
This section contains information necessary when performing the routine
maintenance and occasional adjustment procedures necessary to keep the
MTR-90III in peak operating condition. Many adjustments are seldom, if
ever, necessary, such as those for the brakes, tape lifters, and servos. Other
adjustments, such as head azimuth, will be necessary when playing tapes
made on other machines. Whether or not maintenance seems to be needed,
it is a good practice to check all adjustments periodically. The schedule will
depend on the amount and type of use to which the MTR-90III is subjected,
but a minimum of once every 6 months or 1,000 hours of operation is
recommended.
6.1 Transport Alignment ............................................... 6-2
6.1.1 Transport Deck Plate ............................................. 6-2
6.1.1.1 Opening and Closing the Transport Deck ................... 6-2
6.1.1.2 Removing the Transport Deck Plate ........................ 6-3
6.1.1.3 Reinstalling the Transport Deck Plate ...................... 6-4
6.1.2 Head Geometry .................................................. 6-4
6.1.2.1 Reproduce Head Azimuth .................................. 6-5
6.1.2.2 Record Head Azimuth ......................................6-5
6.1.3 Swing Arm Travel ................................................ 6-6
6.1.4 Fast Forward/Rewind Damping Solenoid Adjustment .............. 6-7
6.1.5 Swing Arm Adjustment ........................................... 6-8
6.1.6 Tape Lifter Mechanism ........................................... 6-8
6.1.7 Brakes .......................................................... 6-10
6.1.8 Reel Turntable Height ........................................... 6-11
6.1.9 Reel Tension Servo Adjustments ................................ 6-12
6.1.9.1 Upper and Lower Limit Adjustment of Reel Tension ....... 6-12
6.1.9.2 Preliminary Center Position and Gain Adjustments ........ 6-13
6.1.9.3 Tape Tension Check ...................................... 6-13
6.1.9.4 Reel Motor Tracking with Capstan ........................ 6-14
6.1.9.5 Fine Adjustment of Position and Gain ..................... 6-15
6.1.9.6 Reel Size Detector Adjustment ............................ 6-15
6.1.10 Capstan Servo Adjustments .................................... 6-16
6.1.10.1 Capstan Tachometer Adjustment ........................ 6-16
6.1.10.2 Adjustment of CAPSTAN CONTROL PCB Assembly ....... 6-17
6.1.10.3 Fast Wind Speed Adjustment ............................ 6-17
6.1.11 Adjustment of TRANSPORT CONTROL PCB Assembly .......... 6-19
6.1.12 Adjustment of MASTER CPU PCB Assembly .................... 6-19
6.1.13 VU Meter Calibration ........................................... 6-19
6.2 Audio Alignment .................................................. 6-20
6.2.1 Reproduce Amp Alignment ...................................... 6-20
6.2.2 Sync Amp Alignment ............................................ 6-21
6.2.3 Bias Alignment .................................................. 6-21
6.2.4 Record Alignment ............................................... 6-22
6.2.5 Record Phase Compensation .................................... 6-23
6.2.6 Erase Current Adjustment ....................................... 6-24
6.2.7 Gain Structure .................................................. 6-24