Ohms Sense Tests - Keithley 2002 Repair Manual

Troubleshooting

2.11.29 Ohms sense tests

Test 600.1 — Ohms sense HI
Type
Fault message
Description
Drawing reference
Components
Bit patterns
2-110
Pass/Fail
Ohms sense HI
A 4-wire short on the input lines applies LO through the path of Q232 and Q231 (turned on by
control line 4WOHM), through Q243 to BUFFIN to the input buffer. BSCOM goes through
Q207 and Q208 to the A/D MUX U226. The gain is X1.
NOTE: The INPUTS and SENSE jacks must be externally shorted together to run this test.
Analog Board; 2002-100
Q207, Q208, Q231, Q232, Q243, and associated components.
—U811—
00001101
—U224—
00010111
—U400— —U432—
01111011 10000000
*Bits associated with register IC terminals as follows:
Q Q Q Q
87654321 87654321
IC pins: Q8=11, Q7=12, Q6=13, Q5=14, Q4=7, Q3=6, Q2=5, Q1=4.
Bit pattern*
—U810—
00000011
—U206—
01100000
—U203—
10101001
—U411—
11111011
Q Q Q Q
87654321 87654321
Register
—U809— AD_STB
11100111
—U207— MUX_STB
00001111
—U221— R1_STB
11100101
—U406— R2_STB
00000100