Figure 4.6.31 Read Write Bus Switch - Fujitsu M2361A Customer Engineering Manual

(5) Read operation
A read operation is initiated by enabling Read gate (Set read/write
command, Bus out bit 3). The analog read/write circuit is always in read
condition so long as the WENB signal is disabled.
The HIC outputs (DX, DY) are applied to the Read/Write Bus Switch IC
(MB4316), amplified, and then sent to Receiver (RB) circuit as shown in
Figure 4.6.31.
DX
To Head
Ie
DY
r
WRITE
- - - - I
r- -------------,
I
DRIVER
I I
AMPLIFIER
I
I L __
~
I
, TO
I
I
RV
I
I I
I I
I
I
I
I
I
.WENS
I
I I
L __________
R~yriteS~Switch
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
J
Figure 4.6.31 Read Write Bus Switch
The Receiver circuit output signal is then applied to the Automatic Gain
Control (AGC) circuit.
The AGC circuit consists of an AGC amplifier IC (MB43303), Equalizer
circuit, LPF (Low Pass Filter) circuit and Reak Detector IC (MB4311).
The AGC circuit develops the control voltage to the AGe amplifier and
holds AGC output amplitude (200 mVp-p) at a constant level. The output of
the AGC circuit is amplified to 2.0 Vp-p, and sent to the Pulse Shaper
circuit.
After going false of WGCTL, the read circuit is activated, however, a
read-transient which is caused by the DC unbalance of the read
pre-amplifier will occur. Therefore, Not Squelch Gate signal (NSQHG) is
enabled about 2~sec after the Write Gate Control signal (*WGCTL) goes
high. The NAQHG signal suppresses this read transient. The profile of
read after write transient wave form is shown in Figure 4.6.32.
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