Keithley 2002 Repair Manual page 100

Bit patterns
Test 408.3 — Setup for test 408.5 and A/D measurement for test 408.6
Type
Fault message
Description
Drawing reference
Bit patterns
—U811—
00001101
—U224—
00010111
—U400— —U432—
01111101 11111111
*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
In this phase, DAC A is programmed with 0s, and the output pin 2 is tied to C461. BUFF is ap-
plied to NET1 (R488) through R493. The divided voltage at pin 4 is tied to AC buffer Q418 and
U423 through U428 and Q422. The signal AMP IN is tied to the circuit through U425, U426, to
Q414. This phase sets up the conditions for the next phase. The voltage on C439 that is buffered
by Q409 (SELFTEST OUT) is tied to U414 pin 11. The output of U414 is tied to the A/D buffer
through buffer U403, R434, R462, and U222. The A/D buffer is configured in X1 gain. This
measurement is saved and used in a comparison in test 408.6.
Analog Board; 2002-100
—U811—
00001101
—U224—
00010111
—U400— —U432—
01111011 00000000
*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—
00111011
Q Q Q Q
87654321 87654321
Bit pattern*
—U810—
00000011
—U206—
01110000
—U203—
10001110
—U411—
00111011
Q Q Q Q
87654321 87654321
Troubleshooting
Register
—U809— AD_STB
11100111
—U207— MUX_STB
11001111
—U221— R1_STB
11101001
—U406— R2_STB
01101100
Register
—U809— AD_STB
11100111
—U207— MUX_STB
11001111
—U221— R1_STB
11101001
—U406— R2_STB
01101110
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