Keithley 2002 Repair Manual

Troubleshooting
2-70
2.11.17 Regulator and switching tests
Test 401.1 — Regulator
Type
Pass/Fail
Fault message Regulator
Description COMMON is routed to the ACF line through U428 (SHORT control line is pulled low). ACF
then goes to multiplexer U414 pin 8 and follows the same path to the A/D buffer as the 400 level
tests. U226 is set up for X1 gain.
Drawing reference Analog Board; 2002-100
Components U403, U414, U418, and associated components.
Bit patterns
Test 402.1 — Frequency switch
Type
Pass/Fail
Fault message Frequency switch
Description U433 (DAC B) is set up to output 4.48V at PRECOMP+, U430 pin 1. The operation of the fre-
quency switch, U425 (FREQ control line pulled low), is verified by dividing the PRECOMP+
voltage by the ratio of R491 and R440. The on resistance of U425 (about 25Ω between pins 2
and 3 must also be added to R440 as this value is also part of the ratio). Again, as in the 400 level
tests, this voltage is routed to the A/D buffer, and U226 is set up for X1 gain.
Drawing reference Analog Board; 2002-100
Components U403, U425, U430, U433, and associated components.
Bit pattern* Register
—U400—
01111011
—U811—
00001101
—U224—
00010111
—U432—
00010111
—U810—
00000011
—U206—
01110000
—U203—
10001110
—U411—
10111011
—U809—
11100111
—U207—
11001111
—U221—
11101001
—U406—
00000101
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