Keithley 2400

4-5 Model 2400 Service Manual
Troubleshooting
2400-902-01 (G - Feb 2006)
There are four voltage ranges: 0.2V, 2V, 20V, and 200V. The feedback gain changes for only
the 20V and 200V ranges, resulting in three unique feedback gain values. A multiplexer directs
the voltage feedback, current feedback, reference, or ground signal to the A/D converter. An
opto-isolated interface provides control signals for both DACs, analog circuit control, and A/D
converter communication to the digital section.
V DAC
I DAC
Control
FB
V Clamp
I Clamp
IFB
VFB
-36
+220
Error
Amp
Output
Stage
Remote
VFB
IFB
+7
A/D MUX
S
Sense
Resistors
Protection
Protection
Output
HI
Output
LO
Guard
Out
Guard
Sense
S+
S-
O
O
O
-220
+36
+
-
Fi
gure 4-
1
A
nalog circuit block diagram