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Fujitsu M255XK Customer Engineering Manual page 23

5 1/4" mini-flexible disk drive
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TPI TP2
Rud,lVrite
coil
Erase coil
eo.on (center tap)
-----------AO
Al
l....I'lrn....t.....L..I
Oiode Iwitch
At
F'-----1
1'-r-r"T"T"""'1"T'-r-'
SIDE 1
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~:f:ii
~:
I
I
I
I
Urite
driver
UD 0.1
VD
L ____________ _
AO-
IP4 IPS tP'3
J
GIlD
Low
YOltap
cletectioo
circuit
LYS
I
I
I
I
VGSO
I
-
---------~
Figure 3-3 Read/Write Circuits
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The read circuits includes a pre-amp, low pass .filter, differential amp, peak
detector, drop detector and read output driver.
Refer to the read circuit timing chart in Figure 3-4.
The micro-voltage level
signals induced into the Read/Write head during playback is amplified by a pre-
amp (a subtraction amplifier) and spurious noise components are removed by a low
pass filter. The amplified signal then goes to the differential amp.
The differential amp shifts the playback signal to the zero crossover position and
simultaneously applies the proper amount of compensation in accordance with the
difference in the frequency components. The signal is further amplified.
The output from the differential amp is converted into a square wave by the peak
detector, the bad influence of the saddle (which occurs during playback of the low-
frequency signal component approximately 125k Hertz) is eliminated by the drop
detector.
The read data signal is driven out of the drive by the read output driver circuit,
when Read Gate is true.
TS-021-013087 ••• 01
3-5

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