Keithley 2002 Repair Manual page 89

Troubleshooting
Bit patterns
Test 405.3 — Small positive DAC V for X10 gain comparison
Type
Fault message
Description
Components
Bit patterns
Test 405.4 — Absolute value X10 gain (non-inverting)
Type
Fault message
Description
Drawing reference
2-76
—U811—
00001101
—U224—
00010111
—U400— —U432—
01011100 10001101
*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 +0.190 VDC at PRECOMP+. This sig-
nal 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 405.4.
Analog Board; 2002-100
—U811—
00001101
—U224—
00010111
—U400— —U432—
01011011 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.
Pass/Fail
Absolute value gain = 10
DAC U433 and op amp pair U430 are set up to generate +0.190 VDC at PRECOMP+. This sig-
nal follows the same path as test 405.2.
Analog Board; 2002-100
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
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