Keithley 2002 Repair Manual

Troubleshooting
2-51
2.11.8 Temperature sensor test
Test 301.1 — Temperature sensor
Type
Pass/Fail
Fault message Temperature sensor
Description The temperature sensor is U205. Pin 1 of U205 is switched through U222 pin 12 to pin 3 of
U226. The X1 gain is achieved by closing U227 pins 2 to 3 with /X1 low. R274 is in the feedback
path of U226. The output of U205 is approximately 10mV per degree Celsius. For example, if
the ambient temperature is 25°C, the output would be 250mV. The measurement at the A/D con-
verter is therefore dependent on the ambient temperature. For the purpose of this test, the limits
of the measurement are 400mV ±400mV. These limits account for the entire specified range of
operating environments.
Drawing reference Analog Board; 2002-100
Components U205 and associated components.
Bit patterns
Bit pattern* Register
—U400—
01111011
—U811—
00001101
—U224—
00010111
—U432—
10000000
—U810—
00000011
—U206—
01110000
—U203—
10001110
—U411—
11111011
—U809—
11100111
—U207—
00001111
—U221—
11101001
—U406—
00000100
AD_STB
MUX_STB
R1_STB
R2_STB
*Bits associated with register IC terminals as follows:
QQQQQQQQ
87654321 87654321 87654321 87654321
IC pins: Q8=11, Q7=12, Q6=13, Q5=14, Q4=7, Q3=6, Q2=5, Q1=4.

Keithley 2002 Specifications

General

Brand	Keithley
Model	2002
Category	Multimeter
Language	English