Keithley 2002 Repair Manual page 87

Troubleshooting
Test 404.4 — Absolute value X1 gain, +half-scale DAC
Type
Fault message
Description
Drawing reference
Components
Bit patterns
Test 404.5 — Absolute value X1 gain, +full-scale DAC
Type
Fault message
Description
Drawing reference
Components
Bit patterns
2-74
Pass/Fail
Absolute value gain = 1
DAC U433 and op amp pair U430 are set up to generate +2.33 VDC at PRECOMP+. This signal
follows the same path as test 404.3.
Analog Board; 2002-100
U403, U414, U417, U419, U428, U430, U433, and associated components.
—U811—
00001101
—U224—
00010111
—U400— —U432—
01011100 10111000
*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 = 1
DAC U433 and op amp pair U430 are set up to generate +4.48 VDC at PRECOMP+. This signal
follows the same path as test 404.3.
Analog Board; 2002-100
U403, U414, U417, U419, U428, U430, U433, and associated components.
—U811—
00001101
—U224—
00010111
—U400— —U432—
01011100 11101100
*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—
11111011
Q Q Q Q
87654321 87654321
Bit pattern*
—U810—
00000011
—U206—
01110000
—U203—
10001110
—U411—
11111011
Q Q Q Q
87654321 87654321
Register
—U809— AD_STB
11100111
—U207— MUX_STB
11001111
—U221— R1_STB
11101001
—U406— R2_STB
01001101
Register
—U809— AD_STB
11100111
—U207— MUX_STB
11001111
—U221— R1_STB
11101001
—U406— R2_STB
01001101