CIRCLUT DESCRIPTIONS
3
3 CIRCUIT DESCRIPTIONS
3.1 INTRODUCTION TO CIRCUIT
DESCRIPTION
3.1.1 General
This chapter prasants a laya rad description of the ScopeMeter circuitry. First the
ScopaM
star's
overall theory
of
operation
Is described, referring to the overall block diagram (section
3.2).
Tho next section gives
some Information conoeming the ScopeMeter’s data acquisition.
Then the circuits
on
both digital
(A1) and analog (A2) pnntad circuit twards (FOB) are described. After
a short introduction,
a
detailed
circuit description is given for each circuit pan.
The various
circuit
descriptions refer to the circuit diagrams in chapter
10.
NOTE: The large digital (A1) and analog (A2) printed circuit board diagrams are provided
as
separate drawings. Whenever a signal line continues on anofher drawing, it is indicated
by
the following
comment:
“FROM A
1
‘
—
> coming
from
the
digital
(A
1
)
drcuit (figure 10.2)
“TO A2a
“
—
> the signal continues on the first circuit diagram of the analog
A2
PCB
(figure 10.5)
3.1.2 Location
of electrical parts
The Item numbers of
C.,., R..„ V,.., H.... D... and K... have been divided Into groups. TTiese groups
relate to the functional parts on the PCBs:
Table 3. 1 Location of electrical parts.
Item number Furtctional part
PCB diagram
'
1200-1299
pP, Oigitaf ASIC and related circuitry
A1
1
A1
1300-1399
battery sense, RAM power, backlight A1 AT
I
1400-1499
1
LCD aryj related circuitry A1
A1
1SOO-1599 ON/OFF circuit
A1 A1
1600-1699
keypad
A1 A1
2100-2199
attenuator channel B
A2 A2a
2200-2299
attenuator channel A
A2 A2a
2300-2399
Analog ASiC and ADC
A2 A2aZb
2500-2599
battery charger
and power supply A2 A2c
2700-2799
EXTemal Input-Zoutpul circuitry
A2 A2b
2800-2899
generator
A2 A2b
2900-2999
analog control circuitry
A2 A2a
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