Technics RS-B965

RS-B965
a __1—__22____i— | g TROUBLESHOOTING OF
DIRECT DRIVE MOTOR
e OUTLINE OF THE DIRECT DRIVE MOTOR SYSTEM
The capstan motor is actuated by the DD motor digital! servo
system. The FG pulse is generated after the detection of
the zero crosspoint, and the reference signal generated from
the quartz oscillator is compared with this FG pulse.
From this comparison, the accelerated and reduced speed
pulses are generated, causing the driving coil to function.
Ov FG SIGNAL
ro ee FG PULSE
| | | | | | | CLOCK PULSE
SPEED UP PULSE AMP ORIVER
n
rt
SPEED DOWN PULSE
¢ TROUBLESHOOTING OF DIRECT DRIVE MOTOR
1. No power supply (+ 12V)
2. The Hail element has failed (Current does
not flow).
3. The ceramic (or crystal) does not oscillate.
Check Points
1. The motor does not
rotate.
¢ Check the voitage applied to the
connector.
¢ Check the DC potential on 10201
pins @~@.
* Check the waveform of I@201 pin (2.
* Check the conductance of the
coil. if normal, the resistances
between IC201 pins (@~d?,
@M~@B,
®~@®,
will
reach
200hms.'
¢ Check the waveform of IC-201 pins
Q~@D.
* Check the waveform of IC pin ©.
e Check if the FG coil is broken.
2. The motor does not rotate | 1. The coil is broken or not properly soldered.
properly. (When pressed, | 2. Output of the Hail element is not proper.
it stops at certain
angles. Sometimes it
does not rotate even if
power is ON.)
3. The motor is out of 1. The FG coil is broken.
control.
4. Abnormal wow 1. Same as those described for problem 2.
Note: Check the points marked with an asterisk (*) by removing the DD motor control P.C.B. and then connecting IC201
pin @ to GND with a lead wire. (After the DD motor control P.C.B. is removed, current will start flowing through
the coil, heating the IC.)
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