Keithley 2002 Repair Manual

Troubleshooting
2-67
2.11.16 Calibration/frequency compensation DAC tests
Test 400.1 — DAC output set to -4.36V
Type
Pass/Fail
Fault message
DAC output not -4.36V
Description
U433 (DAC B) and corresponding circuitry around U430 is configured by programming the
TRIG bits on the DAC to produce -4.36V at PRECOMP+ (pin 1 of U430). This signal is routed
through R491and U412 (DAC control line pulled low). This line, now called ACF, is selected by
multiplexer U414 and is routed out pin 8. It goes to buffer U403, through R462 (where the line
is now called ACV/A), through A/D MUX U222 to the U226 A/D buffer, which is set up for X1
gain.
Drawing reference
Analog Board; 2002-100
Components
U403, U430, U433, and associated components.
Bit patterns
Test 400.2 — DAC output set to -2.15V
Type
Pass/Fail
Fault message
DAC output not -2.15V
Description
This test is the same as test 400.1 except that U433 (DAC B) is configured to output -2.15V.
Drawing reference
Analog Board; 2002-100
Components
U403, U430, U433, and associated components.
Bit pattern* Register
—U400—
01011011
—U811—
00001101
—U224—
00010111
—U432—
00010111
—U810—
00000011
—U206—
01110000
—U203—
10001110
—U411—
11111011
—U809—
11100111
—U207—
11001111
—U221—
11101001
—U406—
00000100
AD_STB
MUX_STB
R1_STB
R2_STB
*Bits associated with register IC terminals as follows:
QQQQQQQQ
87654321 87654321 87654321 87654321
IC pins: Q8=11, Q7=12, Q6=13, Q5=14, Q4=7, Q3=6, Q2=5, Q1=4.

Keithley 2002 Specifications

General

Brand	Keithley
Model	2002
Category	Multimeter
Language	English