Icom IC-R7000 Service Manual page 20

4.4.4 RECORDING SPEECH CIRCUIT (LOGIC UNIT)
When the STOP signal from the MAIN UNIT is applied
to IC3(A), the output of IC3(A) becomes "LOW" for
approximately 1 sec. from the rise of the STOP signal.
When the [RECORDER-SPEECH] SWITCH is ON, after
1 sec. from the rise of the STOP signal (if the VSC
signal is "HIGH"), 05 and 04 are switched on, and
the SPKS signal is output.
5V
D7
EQ4C C13
STOP~------+----.----~
>'--H---.--.....---spKs
~
N
a:
Fig.12
5V
l!RECORDER-SPEECHJ
OFF
: o<J
I
I
I
L ___ _
I
DB~
[VSC)
OFF
4.4.5 SCAN SPEED CONTROL CIRCUIT (LOGIC UNIT)
This circuit accelerates the speed of the MEMORY
CHANNEL SCAN, SELECTED MODE SCAN and
SELECTED MEMORY SCAN.
By the PRIO signal, the output of IC16 remains
"HIGH" even while receiving the another frequency.
When 021 is switched ON by a PRIO or a PRO signal,
C7 is input in parallel with CS, and the clock fre-
quency will decrease.
5V
LOGIC UNIT! [SCAN-SPEED)
064
Fig.13
4·4·6 81 - 84, BH, BS AND VS SIGNALS
co:
ct::
isw2 UNIT
,....
~-----------
ii:
The LOGIC UNIT supplies following signals with the
PLL UNIT and RF UNIT.
RECEIVE FREQUENCY
SIGNALS
FRX [MHz]
B1 B2 B3 B4 BH BS
vs
25- 89.9999
H L L
1025-1089.9999
L H
90- 249.9999
L H
L
L L
1090-1249.999~
- -
250- 511.9999
L L H H L
1250-1511.9999
512- 761.9999
L L
L L
H
1512-1761.9999
H
-
H
-
762- 999.9999
L L
L
H L
1762-1999.9999
B1-B4, BH: BPF signals
BS: Band signal
VS: VCO selector signlal
Table 10
4-10
4·5 DISPLAY CIRCUIT (DISPLAY UNln
This circuit is consists of a fluorescent display tube
DS1, display tube drivers IC1, IC2 and a DC-DC con-
verter circuit.
4·5·1 FREQUENCY DISPLAY CIRCUIT
IC1 drives the display of frequencies while IC2 drives
the display of memory channels.
Signals from the LOGIC UNIT and the MAIN UNIT
control IC1 and IC2.
4·5·2 MODE DISPLAY CIRCUIT
IC2 allocates T3-T7 for five types of data, and IC2
send the segment data "1" to R19.
EXAMPLE:
The AND circuit of
"Q "
and "T7'' is configured with
R18 and R19. 05 and 010 are switched ON by the
timing of "T7" only when
"Q"
is at "HIGH", and
then the letter "SCAN" lights up.
5V
T7
R19
Fig. 14
4.5.3 PRIORITY DETECTOR CIRCUIT
Both the segment "c" and "d" are turned OFF
simultaneously only when DS1 displays the letter
"P". In this case, IC2 switches 014 OFF and IC2
sends the T1 signal to the LOGIC UNIT as a PRIO
signal.
a
I
g
1·
ef
d
v,
' \
Fig.15
R41
016
T1
014
IC2
c
PRIO
c
d
Fig. 16
4·6 KEYBOARD CIRCUIT (KEYBOARD UNIT)
This circuit consists of the keyboard circuit and the
remote control circuit.
The signals from photo-diode D28 are amplified by
IC1 and 01. 01 outputs the remote (REM) signal to
the LOGIC UNIT.