Keithley 2000 Repair Manual

Tables 2-12 through 2-16 can be used to trace the analog signal through the A/D multiplexer
(U163) to the final amplifier stage. These tables show the MUX lines (S3, S4, S6, S7) that are
selected for measurement during the SIGNAL phase of the multiplexing cycle. Also included
are switching states of analog switches (U129) that set up the gain for the final amplifier stage
(U166).
Table 2-9
Ω 2/ Ω 4 reference switching
Range
U133
/.7V
U133
/7V
Q123 Q125 Q124 Q126 Q120
100 Ω
1k Ω
10k Ω
100k Ω
1M Ω
10M Ω
100M Ω
OFF
OFF
OFF
ON
ON
OFF
OFF
ON
ON
ON
OFF
OFF
ON
ON
ON
ON
OFF
OFF
OFF
OFF
OFF
ON
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
Table 2-10
DCA signal switching
Range K103
10mA
100mA
1A
3A
ON
OFF
OFF
OFF
Table 2-11
ACA signal switching
Range K103
U105
pin 16
U105
pin 1
U111
pin 16
U105
pin 8
U103
pin 16
U103
pin 1
1A
3A
OFF
OFF
ON
ON
ON
ON
OFF
ON
OFF
OFF
OFF
OFF
OFF
OFF
Troubleshooting 2-15

Keithley 2000 Specifications

General

Digits	6.5
DC Voltage Range	100 mV to 1000 V
AC Voltage Range	100 mV to 750 V
Resistance Range	100 Ω to 100 MΩ
Connectivity	IEEE-488 (GPIB)
Display Type	VFD