Keithley 2700 Service Manual

Troubleshooting 4-9
Figure 4-3
Analog circuitry block diagram
INPUT HI
INPUT HI protection is provided by the SSP (Solid State Protection) circuit. The SSP is pri-
marily made up of Q101 and Q102. An overload condition opens Q101 and Q102, which dis-
connects the analog input signal from the rest of the analog circuit.
Note that for the 100VDC and 1000VDC ranges, Q101 and Q102 of the SSP are open. The
DC voltage signal is routed through the DCV Divider (Q114 and Q136 on) to the DCV switch-
ing circuit.
Scanner
Inputs
BUFCOM
Slot 1
INPUT
HI
SENSE
LO
Scanner Outputs
DCV
OHMS
DCV/100
Current
Shunts
K103, R158,
R205, R338
AC Switching
&
Gain
K102, U102, U103, U105,
U112, U118, U111, U110
SSP*
Q101, Q102
DCV
Divider
R117, Q109,
Q114, Q136
Ohms I-Source
Q119, Q123,
Q124, Q125, Q126,
U123, U133
DCV & Ohms
Switching
Q104, Q105
Q108, Q113
X1
Buffer
U113
Digital
Circuitry
(See Figure 4-2)
ADC
U165
A/D
MUX &
Gain
U129, U132
U163, U166
SENSE
HI
ACV,
FREQ
AMPS
DCA
ACA
Slot
Control
* Solid State Protection
X1
Buffer
U167
Front Terminals
Scanner Outputs
K101
Q120, CR114
Protection
R132, R139, R148,
R163, Q122, Q135,
VR119, VR120
Protection
R120, R121, R124,
R125, Q107, Q148,
VR119, VR120
Front Terminals
Scanner Outputs
Front Terminals
Scanner Outputs
Front Terminals
Scanner Outputs
Scanner
Inputs
Slot 2
S101
S101
S101
S101

Keithley 2700 Specifications

General

Type	Digital Multimeter
Measurement Functions	DC Voltage, AC Voltage, DC Current, AC Current, Resistance, Frequency, Temperature
DC Voltage Range	100 mV to 1000 V
AC Voltage Range	100 mV to 750 V
Frequency Range	3 Hz to 500 kHz
Temperature Range	-200°C to +1372°C
Display	Vacuum Fluorescent Display
Connectivity	IEEE-488, RS-232
Channels	10
Power Supply	100V to 240V AC, 45Hz to 66Hz
DC Current Range	10 µA to 3 A
AC Current Range	10 µA to 3 A
Temperature Measurement	Thermocouple, RTD