Keithley 2002 Repair Manual page 101

Troubleshooting
Test 408.4 — Correction factor
Type
Fault message
Description
Drawing reference
Bit patterns
Test 408.5 — Signal stored for test 408.6
Type
Fault message
Description
Drawing reference
Bit patterns
2-88
Circuit Exercise
None
This test is the same as test 408.3 except that no measurement is taken.
Analog Board; 2002-100
—U811—
00001101
—U224—
00010111
—U400— —U432—
01111101 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.
Circuit Exercise
None
The SELFTEST control line turns ON Q425 and forces the voltage on NET1 (R488) to ground.
The response of R488 pin 4 is stored in C439. This test uses the same path as test 408.1 except
as follows: when the SELFTEST control line forces the divider voltage to zero, it also generates
a one-shot pulse 5µs after SELFTEST goes low. This pulse turns Q414 on and stores the voltage
on C439. The 5µs delay that controls U425 and Q414 is generated by U402. No measurement
is made during this phase.
Analog Board; 2002-100
—U811—
00001101
—U224—
00010111
—U400— —U432—
01111101 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
Register
—U809— AD_STB
11100111
—U207— MUX_STB
11001111
—U221— R1_STB
11101001
—U406— R2_STB
01101110
Register
—U809— AD_STB
11100111
—U207— MUX_STB
11001111
—U221— R1_STB
11101001
—U406— R2_STB
01101100