Teac FD-55 Series, Maintenance Manual

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(a) Confirmation and adjustment of the disk rotational speed. Speed is
adjusted by the variable resistor R1 on the PCBA DD motor servo.
Note: Some types of DD motor Ass'y have not the variable resistor Rl
for rotation speed adjustment. In such a DD motor Ass ry , no
adjustment is required and the rotation speed is determined by an
oscillation frequency of the ceramic oscillator mounted on the
PCBA DD motor servo.
(b) Confirmation and adjustment of the index burst timing. Burst timing
is adjusted by the fixing screws of the PCBA front OPT.
TP4 (Index)
n • .....
J
n
Index
interval
Pulse width
(Fig.315) Typical waveform of TP4 (Speed observation)
Items
FD-55A ^ P FD-55G
Index interval 200±3ms 166.7±2.5ms
Pulse width
2 'v 5:. 5ms 1 'v 8ms
Burst delay 200± 200ys 165±165ys
(Table 303) Index timing
TP4 (Index)
TP7 or 8
/
f-AAAA . . - ...
(Pre-amp. output)
a
vvv
Index burst delay
(Fig.316) Typical waveform of TP4 (Burst timing observation)
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