Omega 871A, Руководство пользователя

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TABLE 3-1
MODEL 871A AND MODEL 872A
CONTROLS AND INDICATORS
ITEM CONTROL/INDICATOR FUNCTION
1. ON/OFF switch Turns unit on or off.
2. Scale and range selector Allows user to select: ºF or ºC scale,
any of four possible thermocouple
ranges, and 1.0º or 0.1º resolution.
3. Thermocouple selector Allows user to read either of two
thermocouples by simply turning
the dial.
4. Thermocouple input jacks Allows direct connection of two
thermocouples to the unit via an
OMEGA miniature male connector.
5. Analog output jack, The analog output is a nonlinearized,
+mV OUT and -mV OUT cold junction compensated, amplified
thermocouple output. (Not isolated
from selected TC input.) Use a
recorder to monitor temperature or
a sensitive DMM to make higher
resolution reading. Refer to mV
output specifications for mV output
to temperature ratios.
6. Low battery indicator When the battery level is low, BAT
will appear in upper left corner of
the display. Battery should then be
replaced to avoid error erroneous
readings due to battery failure.
7. Overrange/open When an overrange indication or
thermocouple indication open thermocouple condition exits,
a 1 followed by blanked digits will
appear in the display.
4
Circuit Description
Desig.
R116** R116, R122, and U109 are a
selected set
R117 Thick Film Resistor Network
R118* Resistor, 150 k
Ω
, 5%, 1/4W,
Comp
R118** Resistor, 5.6 k
Ω
, 5%, 1/4W,
Comp
R119 Thick Film Resistor Network
R120 Resistor, 10 k
Ω
, 5%, 1/4W,
Comp
R121** Resistor, 10.0 k
Ω
, 6.1%, Metal
Film
R122*† Resistor , Selected, 5%, 1/4W,
Comp
R122** R116, R122, and U109 are a
selected set
R123* Resistor, 324 k
Ω
, 1%, 1/8W, Mtf.
R123** Resistor, 316 k
Ω
, 1%, 1/8W, Mtf.
R124** Resistor, 10.0
Ω
, 0.1%, Metal
film
R126* Resistor, 10 k
Ω
, 0.1%, MF
R127* Resistor, 9.9 k
Ω
, 0.1%, MF
R128* Resistor, 4.7 k
Ω
, 5%, 1/4 W,
Comp
S101 Switch, Rotary
S102 Switch, Rotary
S103 Switch, SPDT, ON-OFF
TC-1, 2 TC Cable
Circuit Description
Desig.
U101 3
1
⁄2 Digit Single Chip A/D
Converter
U102 Dual Synchronous Up Counter
U103, U104* Low Power JFET Input Op Amp
U103, U104** Dual JFET Input Op Amp
U105 COS/MOS Quad Bilateral Switch
U106 CMOS Quad Exclusive OR Gate
U107 Dual “D” Type Flip-Flop
U108 14 Stage Binary Counter
U109* Linear Op Amp
U109** R116, R222, and U109 are a
selected set
U110* Current Source
U110** R115 and U110 are a
selected set
U111 Quad, 2 Input NOR Gate
U112 COS/MOS Divide by “N”
Counter
U113 Quad, 2 Input, AND Gate
U114 Analog Multiplexer
Y101 Resonator, 360 kHz
† Value selected during calibration at factory.
* For Model 871A only
** For Model 872A only
To order parts, specify model and circuit designation.
5.1 PARTS LIST (continued)
17
R120
R127
Jumper
R124
Jumper
R121
R118A
COMPONENT LAYOUT FOR MODEL 871A
COMPONENT LAYOUT FOR MODEL 872A