Keithley 2002 Repair Manual page 90

Components
Bit patterns
Test 405.5 — Small negative DAC V for X10 gain comparison
Type
Fault message
Description
Drawing reference
Bit patterns
U403, U408, U412, U414, U417, U419, U430, U433, and associated components.
—U811—
00001101
—U224—
00010111
—U400— —U432—
01011100 10000101
*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.
Circuit Exercise
None
DAC U433 and op amp pair U430 are set up to generate -0.210 VDC at PRECOMP+. This signal
follows the same path as test 405.1. This test has the same purpose as test 405.1, but the new test
value is used for test 405.6.
Analog Board; 2002-100
—U811—
00001101
—U224—
00010111
—U400— —U432—
01011011 01111011
*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—
01110000
—U203—
10001110
—U411—
11111111
Q Q Q Q
87654321 87654321
Bit pattern*
—U810—
00000011
—U206—
01110000
—U203—
10001110
—U411—
11011111
Q Q Q Q
87654321 87654321
Troubleshooting
Register
—U809— AD_STB
11100111
—U207— MUX_STB
11001111
—U221— R1_STB
11101001
—U406— R2_STB
01001111
Register
—U809— AD_STB
11100111
—U207— MUX_STB
11001111
—U221— R1_STB
11101001
—U406— R2_STB
01001111
2-77