Keithley 2001 - Page 49

Troubleshooting
2-36
Test 201.2 – 7V reference
Pass/Fail
Cannot measure 7V at A/D IN.
This test turns on Q328 by setting /HIV low and turns on Q525 by setting /DIVIDER
low. Switches U317 (/REF pulled low) and U318 (/X1 pulled low) are closed and U808
is set for line cycle integration.
REF OUT (7V) is connected to the A/D buffer at x1 gain and is then applied to the A/
D converter. The A/D is triggered and the REF OUT counts are stored and compared
to a design REF OUT value.
U330, U329, U328 and associated resistors and capacitors.
DC_STB
Registers
R1_STB
Registers
R2_STB
Registers
U801 Q1: 0
Q2: 1
Q3: 1
Q4: 1
Q5: 1
Q6: 0
Q7: 0
Q8: 0
U307 Q1: 1
Q2: 1
Q3: 0
Q4: 1
Q5: 1
Q6: 1
Q7: 1
Q8: 1
U505 Q1: 0
Q2: 0
Q3: 1
Q4: 0
Q5: 0
Q6: 0
Q7: 0
Q8: 0
U800 Q1: 1
Q2: 1
Q3: 0
Q4: 0
Q5: 0
Q6: 0
Q7: 1
Q8: 1
U305 Q1: 1
Q2: 0
Q3: 1
Q4: 0
Q5: 0
Q6: 0
Q7: 1
Q8: 1
U500 Q1: 1
Q2: 1
Q3: 0
Q4: 1
Q5: 1
Q6: 1
Q7: 1
Q8: 1
U300 Q1: 1
Q2: 1
Q3: 0
Q4: 1
Q5: 1
Q6: 1
Q7: 1
Q8: 0
U302 Q1: 1
Q2: 1
Q3: 1
Q4: 1
Q5: 1
Q6: 1
Q7: 1
Q8: 0
U530 Q1: 0
Q2: 0
Q3: 0
Q4: 0
Q5: 0
Q6: 0
Q7: 0
Q8: 1
U303 Q1: 0
Q2: 1
Q3: 1
Q4: 1
Q5: 1
Q6: 1
Q7: X
Q8: X
U501 Q1: 1
Q2: 1
Q3: 0
Q4: 1
Q5: 1
Q6: 1
Q7: X
Q8: X
Note: Tables 2-10 through 2-12 provide functional descriptions of the register bits.
Type
Failure analysis
Description
High suspect
components
Bit pattern