Keithley 2750 Service Manual

4-22 Troubleshooting Model 2750 Multimeter/Switch System Service Manual
Table 4-14 through Table 4-19 can be used to trace the analog signal through the A/D mul-
tiplexer (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).
Tab le 4- 14
DCV signal multiplexing and gain
Range
Signal
(U163)
U129
Pin 1
U129
Pin 8
U129
Pin 9
Gain
(U166)
100mV
1V
10V
100V
1000V
S4
S4
S4
S4
S4
OFF
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
OFF
OFF
OFF
100
10
1
10
1
Tab le 4- 15
ACV and ACA signal multiplexing and gain
Range
Signal
(U163)
U129
Pin 1
U129
Pin 8
U129
Pin 9
Gain
(U166)
All S3 ON OFF OFF 1
Tab le 4- 16
DCA signal multiplexing and gain
Range
Signal
(U163)
U129
Pin 1
U129
Pin 8
U129
Pin 9
Gain
(U166)
20mA
100mA
1A
3A
S6
S6
S6
S6
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
OFF
100

100
100
10

Keithley 2750 Specifications

General

Interface	GPIB, RS-232, Ethernet
Switching Speed	Up to 500 channels/second
Maximum Voltage	300V
Operating Temperature	0°C to 50°C
Measurement Functions	DCV, ACV, DCI, ACI, 2-wire Resistance, 4-wire Resistance, Frequency, Temperature
Resolution	6.5 digits
Current	1A
Maximum Current	1A