HP 740B Operating And Service Manual page 88

Model 740B Section VII
F==============================MAIN LOOP ==============================::;]
-============LOW VOLTAGE
Ir
SECTION ===========~ --================HIGH VOLTAGE===================;]
Ir
SECTION
OVERLOAD
PROTECTION
IiiCl ,.... --,
~
O-I~
VDC
INPUT
FILTER
O-IOOO[VDC
PIC AI7
MODULATOR
0-1000
VDC
PIa
SI
RANGE
DIVIDER
A3
- LOW LEVEL
AMPLIFIER
PIO 51
. - PIO AI7
f----
OPE~~T~O~AL
DEMODULATOR FILTER
riVTOl
l!QQ.QYJ
PIO A5
PULSE WIDTH -
CONVERTER
PIO A7
POWER
SWITCH
DR IVER
----
POWER
SWITCH
PULSE
~ TRANSFORMER - - - -
8 RECTI FIER
FILTER
OUTPUT
FILTER
,....-----, I
DC OUTPUT
I
K I
OUTPUT --<0-1000
CONTROL VDC
ZERO
SET
o
f"iMVTOl
~
Pia
A5
20KHZ CLOCK
PIO
A3
OVERLOAD
DETECTOR
O-IVDC
H. V.
SECTION
FEEDBACK
DIVIDER
O-IOOOVOC
O-IOOOVDC
[
- - = t . . . . - ' - M _ O _ ~ _ / ~ . , L
. .. :_';_O_R .....
~~LD_E_:_~_~_U_~_~_T_0_R"-~>-M-'-6'---'---'
METER
FIUER
--===============METER ===============::;]
~ LOOP ~
AI3
REFERENCE
SUPPLY
52
SENSITIVITY
SWITCH
54-58
O-IVDC -
BIN;:;'MC.,o~ED
f -
IVDC
DIVIDER
--===.REFERENCE===~
~-
LOOP
~
+
FUNCTION
SWITCH
51
FUNCTION
SWITCH
51
,-------------------------i--<:>-O-,--0-
I31MJ
I
I
I
I
I
I
I
I
I
I
O-IVDC
MAIN LOOP
FEEDBACK
DIVIDER
1I000vi
0"'0--0--;---'
nMVl
l..!2....!Y.J
¢---+----::---::4:c:+--o-o--+----I
740B-D-0726A
METER LOOP
FEEDBACK
DIVIDER
Figure 7 -1. DC Voltmeter and Differential
Voltmeter Block Diagram
01794-1 7-3/7-4