Keithley 2000 Repair Manual

Digital circuitry
Refer to Figure 2-2 for the following discussion on digital circuitry.
Table 2-1
Power supply circuits
Supply Rectifier Filter Regulator
+5VD
+37V
+15V
-15V
+5V, +5VRL
CR104
CR116, CR117
CR102
CR102
CR103
C128, C156
C104, C108
C148
C131
C146
U144
U101
U125
U119
U124
Figure 2-2
Digital circuitry
block diagram
Analog
Circuitry
(See Figure 2-3)
NVRAM
U136
ROM
U156, U157
RAM
U151, U152
XADTX
XADCLK
XADTS
XADRX
O
P
T
O
I
S
O
ADTX
ADCLK
ADTS
ADRXB
68306
µP
U135
Scan Control
Keypad
Display Board
Controller
Display
DS401
XTAL
Y101
Trigger
U146, U164
Trigger
Link
TRIG IN
TRIG OUT
AT101
U150
U155
IN
OUT
RS-232
U159
Data IN
Data OUT
GPIB
RS-232
Port
IEEE-488
Bus
U158, U160,
U161
U401
Troubleshooting 2-7

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