Fluke 45 - Analog Simplified Schematic Diagram

45
Service Manual
2-8
K1
28 29 30 31 32 33 36 37 39
VDD
VDD
VCC
DIGR
DIGS
U4
U3
40
Y1
Digital Section
3.84 MHz
K2 K3
Relay
Drivers
U2
Current
Shunts
and
Protection
Input
Protection
C1
K3
ACV
AC mA
R4
Gain Control
1k
10k
1M
100K
DCV Lo/RRS Lo
mA output
mV DC all ohms diode test
amps
R8
mA Com V/Ω Hi
Ω
K2
DCV
Z1
Z1 10M
VDC/MΩ
3V
300 mV
1000V
300Ω
300V
3 kΩ
300 kΩ
3 0 kΩ
30V
Low
3
8765 2 68 61
11
13 14
Divider Switching
15 16 19 21 23
S2
S3
25
10A
amps output
RRS = Reference Resistor Sence
Ohms
Voltage
Source
To Reference Resistors
To ohms Source & RRS Hi
U1Analog
Measurement
Processor*
* Not all U1 switches are shown here.
Refer to the schematic diagram in Chapter 8.
RMS
Converter
AC Buffer
Serial Communication
S37
S18 S19
S81
RRS
Lo
RRS Lo
RRS Hi
DC Hi
S42
S38
S35
Frequency
Counter
A/D
A/D Lo
A/D Hi
56 51
Z3 A/D
Ref
52 56 59 60
Active
Filter
C21
C13C12
R22
VDD
VR1
C15
1.1V
qb02f.eps
Figure 2-2. Analog Simplified Schematic Diagram