Keithley 2002 Repair Manual

Troubleshooting
2-58
2.11.12 20V range multiplexer tests
Test 305.1 — 20V range multiplexer REFHI
Type
Pass/Fail
Fault message 20V range MUX REFHI
Description Q201 is turned on, allowing 7.2V REFHI to be applied to the R240 divider. Q203 is always on
because its gate and source are tied together by R241. Since R240 divides by 2, 3.6V appears at
U217 pin 3. Because U217 is a unity-gain buffer, 3.6V also appears at R261, and U222 switches
pin 7 to pin 3 of U226. X1 gain is achieved by closing U227 pins 2 to 3 with /X1 low. R274 is
in the feedback path of U226.
Drawing reference Analog Board; 2002-100
Components Q201, U217, U222, U226, and associated components.
Bit patterns
Bit pattern* Register
—U400—
01111011
—U811—
00001101
—U224—
00010111
—U432—
10000000
—U810—
00000011
—U206—
01110010
—U203—
10001110
—U411—
11111011
—U809—
11100111
—U207—
01110111
—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

Resolution	8.5 digits
DC Voltage Accuracy	±0.0006%
Maximum DC Voltage	1000 V
Maximum AC Voltage	750 V
Maximum DC Current	3 A
Maximum AC Current	3 A
Connectivity	GPIB, RS-232
DC Voltage Range	100 mV to 1000 V
AC Voltage Range	100 mV to 750 V
Resistance Range	10 Ω to 1 GΩ
Model	2002
Category	Multimeter
Interface	GPIB, RS-232
AC Current Accuracy	±0.1%
Frequency Range	0.1Hz to 300kHz
Display	VFD
Type	Digital
Power Supply	100-240V AC, 50/60Hz
Current Range (DC)	100 μA to 3 A
Current Accuracy (DC)	±0.01%
Current Range (AC)	100 μA to 3 A
Current Accuracy (AC)	±0.1%
DC Current Range	100 μA to 3 A
AC Current Range	100 μA to 3 A