Keithley 2002 Repair Manual

Troubleshooting
2-55
2.11.10 Input buffer tests
Test 303.1 — Input buffer
Type
Pass/Fail
Fault message Input buffer
Description This is the first test in the series that actually takes a measurement from the BUFFIN line by us-
ing the R1_STB default condition described earlier (see the discussion on default state in para-
graph 2.11.5). Common is switched through U244 pin 11 to 10, through Q226, the lower leg of
the R335, R339, R341, R346 series parallel combination, through Q242 to BUFFIN. BUFFIN
goes into the bootstrap supply and U245 input buffer (including the U249 servo). The input buff-
er output, BSCOM, goes through Q207 and Q208 to pin 3 of U226. The A/D MUX gain is X1.
Drawing reference Analog Board; 2002-100
Components U226, U244, U245, and associated components.
Bit patterns
Bit pattern* Register
—U400—
01111011
—U811—
00001101
—U224—
00010111
—U432—
10000000
—U810—
00000011
—U206—
01100000
—U203—
10001110
—U411—
11111011
—U809—
11100111
—U207—
00001111
—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