Keithley 2002

Troubleshooting
2-111
Test 600.2 — Ohms sense LO
Type
Pass/Fail
Fault message Ohms sense LO
Description A 4-wire short on the input lines applies LO through the SENSE_LO path of R360, U242 pins
15 to 14, to the ADGND MUX U253, then to the A/D MUX at U226. Common is routed through
U222 S1 to U226 pin 3. A/D MUX gain is X1.
NOTE: The INPUTS and SENSE jacks must be externally shorted together to run this test.
Drawing reference Analog Board; 2002-100
Components R360, U242, 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—
11111101
—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.