Keithley 2520, Service Manual, Page: 82 / 137

4-10 Troubleshooting Model 2520 Pulsed Laser Diode Test System Service Manual
Power supply
Figure 4-3 shows a block diagram of the Model 2520 power supply system. The supply
has two separate power transformers, T1 and T2, as well as both regulated and unregu-
lated supply voltages.
Unregulated circuits include the -8VF1 supply and -25VF1 supply that powers the output
stage. Regulated circuits include ±5VFA, ±12VF, +12VD, and ±25VF supplies to power
the various circuits throughout the instrument.
Figure 4-3
Power supply block diagram
Analog Circuits
± 5V
+5VD
Line In
Line
Filter
Digital
Circuits
Digital
Supply
Power
Transformers
100-240V AC
Analog Supplies
± 25V
±
25V
Current
Source
Output
Stage
± 12V ± 8V
+12VD