Sony BVH-2000, Operation And Maintenance Manual

Page: 303 / 505

(5-5-3. DT-04/-05 Board)
21. Head Wobbling Detector
In addition to the wobbling components, the PB RF signal
DT also contains resonance and
other components as well as delay and mechanical distortion
created by wobbling the bimorph leaf. Therefore, the status of
the actual DT head tracing is detected from the output of the
strain gauge which is mounted
on the bimorph leaf.
The strain gauge signal from the head drum is to IC
3 while the output of the integrator IC IN -1 is supplied to IC IL-
2, the two signals are subtracted,
the slope waves are removed,
HEAD WOBBLING DETECTOR
(t:::
o::
t:{:
}Ci1
1e21
JUMP
CD
INTEGRATOR
z
o
i=
«
a:
w
CL
o
LL
o
r
a:
o
w
I
l-
ui
®ST GAUGE
the undesirable components are filtered out by the high -pass
filter and the into the
multiplexer IC2K of the tracking error detector as the FILT ST
(Filtered Strain Gauge) signal.
In order to incorrect of the
head, the current rushing into the integrator is detected by Je2l.
When exceeds
±
120 mV, 1I is turned off and the FIL T ST
signal output is inhibited.
ERROR
G)INTEGRATOR
®ST GAUGE
®FILT
22. Tracking Error Detector
This circuit serves to multiply the envelope signal from the
EQ board and the FILT ST signal from the head wobbling
detector and to detect the error.
The RF envelope signal from the EQ board is sampled by
IC 1M-IS at the timing of the PB H signal, it is further amplified
by approximately 30 dB by and it is to
multiplier IC2K through the high -pass filter IC 11. The tracking
error is sent to the output of the IC2K. fact,
TRACKING ERROR DETECTOR
the neighboring double of the are filtered
out by the high-pass filters IC2M, the frequencies mainly
imbalance in the are filtered out the
notch filter IC2N, and the remaining signal is output to the
bimorph drive signal generator.
FILT ST-~- ....
IC2K
CAR
SIG
RF ENVELOPE
-..--------------l-.l
(From EO Board) ...... _-~
PB H
(SAMPLING PULSE)
DYNAMIC TRACKING SYSTEM
5-5-12 BVH-2000(U/C)/PS/PM
BVH-2180(U/C)/PS/PM