- 7 -
4.3.3 A/D conversion and display output circuit: The output voltage from the pin 3 of
N419 passes through N420B where it is amplified and sent to the opposite-phase
terminal of N420A. N420A composes a voltage comparer. We'll discuss its detailed
working process according the voltage comparing characteristics (When the in-phase
end's voltage is higher than that of the opposite-phase end, the output is the positive
power. When the in-phase end's voltage is lower than that of the opposite-phase end,
the output is the negative power.) and the figure 4.
When the opposite-phase end has a DC voltage representing 35Hz signal amplitude,
the output of N420A is a low level close to the negative power supply. At the same time,
+5V provides conditions for V436 to be conductive and a high level from the collector
of V436 charges C530. The positive end's voltage of C530 (i.e. the in-phase end of
N420A) is increasing gradually. When the voltage reach that of the opposite-phase
end, the voltage comparer will overturn. Therefore, N420 sends out a high level close
to the positive power supply voltage. When the comparer overturns, CPU will
terminate the 35Hz level selection and switch to the next frequency 100Hz. During the
switch interval, an instantaneous high level from the pin 1 of CPU makes V435
conductive and the voltage of C530 will be released. The in-phase end of N420A will
be charged from 0 level to 100Hz. When 100Hz charge is finished, it will switch to the
next frequency. The process is circulated under CPU's control. The charging time from
the 0 level to overturn represent current frequency's signal amplitude. The amplitude
is large, time is longer; the amplitude is small, time is shorter. We can conclude from
the above circuit working process: An analog series of DC level which has concrete
voltage value originally becomes two mode of 0 and 1. Its time period represents the
digital pulse of the original information. That is to say, it finishes the analog-to-digital
conversion process. The digital pulse sent out from the output terminal of N420A
reaches the pin 12 of CPU after opposite-phased by V437. And then CPU processes
it and sends it to front panel display IC N901 which will make dynamic spectrum
display on the display. As a matter of fact, every frequency is displayed sequentially.
However, what we see on the display screen is the working process all the spectrums
are displayed simultaneously due to every frequency display circulate very quickly.
V
T
3
5HZ
100HZ
Switch time interval
V
T
35HZ
100HZ
Charge time
Charge time
High level
discharge
(Figure 4)
- 20 -
127
CONNECTION
CORDS
¦ µ
0.6 SHAPED 10mm
W4,W6,W7,W9,W13,W17,W23,W25,W29,W31,W32,W35,
W40,W41,W44~W47,W54,W55,W62,W65,W80,W90,W97,
W103,W111,W112,W117,W121,W122,W133,W137,W142,
W143,W154,W163,W167,W168,W174,W177,W178,W180,
W181,W185,W186,W190,W207,W208,W209,W37
128
CONNECTION
CORDS
¦ µ
0.6 SHAPED 12.5mm
W57,W60,W67,W68,W70,W71,W77,W93,W104,
W120,W123,W124,W128,W130,W131,W144,W145,W148,
W204
129
CONNECTION
CORDS
¦ µ
0.6 SHAPED 15mm
W83,W85,W86,W107,W115,W126,W129,W146,W147,
W169~W173,W175,W176,W182,W183,W191,W201,W82
130
CONNECTION
CORDS
¦ µ
0.6 SHAPED 20mm
W33,W34,W48,W51,W114,W132,W134,W141,W166,W192,
W196,W200,W203
131 CABLE
20# 60mm BLACK WITH CHIP
SOLDER
GROUND WIRE
132 CABLE
18# 70mm BLACK
XJ1~XJ2
CABLE
22
£ £
80mm BLACK
XJ1~XJ2
133 FUSE TUBE
T6.3AL 250V
FL403,FL404
134 FUSE TUBE
T4AL 250V
FL405,FL401,FL402
135 FUSE HOLDER
BLX-2
FL405
136
RADIATOR
BOARD
30×16×16 AB207
SRQ401
137
LARGE
RADIATOR
267.5×91×70 AV210
CONNECTED TO THE MAIN AMPLIFICATION BOARD
138 FUSE HOLDER
0 FL401~FL404
139 SMALL CHIP
AB207
FIX TRIODE
140
ANGLE
ALUMINUM
90×23.2×30 AV210
POWER IC / LARGE RADIATOR
141
TAPPING
SCREW
BT 3×8 BLACK
2 FOR RADIATOR BOARD/MAIN AMPLIFICATION BOARD,
1 FOR N412/RADIATOR BOARD
142
TAPPING
SCREW
PB 3×12H COLOR ZINC
2 FOR SMALL CHIP/LARGE RADIATOR, 5 FOR ANGLE
ALUMINUM/LARGE RADIATOR
143
TAPPING
SCREW
PWT 3×8×8 COLOR ZINC
1 FOR MAIN AMPLIFICATION/RADIATOR, GROUNDED
144
TAPPING
SCREW
BT 3×8H COLOR ZINC
1 FOR MAIN AMPLIFICATION/RADIATOR, 3 FOR ANGLE
ALUMINUM/POWER IC
145
MACHINE
SCREW
PWM 3×16×8 COLOR ZINC
4 FOR POWER TUBE/LARGE RADIATOR
146 SCREW NUT
M3
147
SCREW
SPACER
¦ µ
3×7.2×0.5
148
SPRING
SPACER
¦ µ
3
149
INSULATION
RING
¦ µ
3×6×3
N413~N415
150 MICA SPACER
18
×
13
×
0. 1
151 MICA SPACER
22
×
19
×
0. 1
4 FOR POWER TUBE / RADIATOR
