Keithley 2002 Repair Manual

Troubleshooting
2-53
Bit patterns
Test 302.3 — Ohms LO to ADGND
Type
Pass/Fail
Fault message Ohms LO to ADGND
Description Common is switched through the parallel combination of R313 and R314 and U242 pins 10 to
11, through R311 and to pin 3 of U253. U253 is the buffer for ADGND. ADGND buffer with
Ohms LO signal is connected to the bottom of the parallel combination of R285 and R286. To
ensure stability of the circuit, X1 gain is achieved by closing U227 pins 2 to 3 with /X1 low.
R274 is in the feedback path of U226. Pin 3 of U226 is also pulled to common through U222
pin 4 and R259.
Drawing reference Analog Board; 2002-100
Components U222, U226,U227, U242, U253, 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—
00010111
—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.
Bit pattern* Register
—U400—
01111011
—U811—
00001101
—U224—
00010111
—U432—
10000000
—U810—
00000011
—U206—
01110000
—U203—
10001110
—U411—
11111011
—U809—
11100111
—U207—
00011011
—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