Keithley 6512 Instruction Manual page 124

Table 7-11
A/D converter checks
Step Item/component
1
2 U127, pin 10
3 U127, pin 7
4 U127, pin 6
5 U127, pin 5
6 U127, pin 3
7 U127, pin 1
8 U135, pin 6
9 U138, pin 7
10 U137, pin 10
11 U137, pin 7
12 U126, pin 6
13 U135, pin 8
14 U136, pin 10
15 U126, pin 9
Table 7-12
Preamplifier checks
Step Item/component
1 Range
2 Apply 190mV DC input
3 Apply 1.9V DC input
4 Apply 19V DC input
5 Apply 190V DC input
6 Function, range
7 Apply 1.9mA input
8 Range
9 Apply 19mA input
10 Range
11 Apply 190µA input
12 Function
13
14 Function
15 R304, pin 1
16 R304, pin 2
17 R304, pin 3
Required condition
Turn on power, select 2V range, and short input.
1.2288MHz gated clock
307.2kHz gated clock
153.6Hz gated clock
76.8kHz gated clock
38.4kHz gated clock
300Hz gated clock
+5 to ≈ 0V pulse train 3µsec every 22µsec
Integrator ramp
≈ 1.5V DC
Variable pulse train 0V to +5V
Variable pulse train 0V to +5V
Variable pulse train 0V to +5V
≈ 5msec positive-going pulse
100msec positive-going pulse
Required condition
Power-on, 200mV range, zero check off
190mV
1.9V
19V
190V
Select AMPS, 2mA range 1.9V
1.9V
Select 20mA range
1.9V
Select 190µA range
19V
Select VOLTS, enable zero check
0V
Select OHMS
10V, ±0.1V
1V, ±0.01V
0.1V, ±0.001V
Remarks
All A/D checks referenced to
analog common.
A/D clock.
A/D synchronous clock.
A/D synchronous clock.
A/D synchronous clock.
A/D synchronous clock.
A/D synchronous clock.
Charge balance synchroniza-
tion signal.
Comparator reference.
Comparator output.
Reference current generator.
A/D data output.
Control line for charge bal-
ance/single slope.
Integrator control line.
Remarks
Measure at PREAMP OUT and COM
unless otherwise noted.
Remove before selecting amps function.
Zero correct if necessary.
Referenced to PREAMP OUT.
Referenced to PREAMP OUT.
Referenced to PREAMP OUT.
Maintenance
7-15