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Maintenance
7-15
Table 7-11
A/D converter checks
Step
Item/component
Required condition
Remarks
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
U127, pin 10
U127, pin 7
U127, pin 6
U127, pin 5
U127, pin 3
U127, pin 1
U135, pin 6
U138, pin 7
U137, pin 10
U137, pin 7
U126, pin 6
U135, pin 8
U136, pin 10
U126, pin 9
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
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.
Table 7-12
Preamplifier checks
Step
Item/component
Required condition
Remarks
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Range
Apply 190mV DC input
Apply 1.9V DC input
Apply 19V DC input
Apply 190V DC input
Function, range
Apply 1.9mA input
Range
Apply 19mA input
Range
Apply 190µA input
Function
Function
R304, pin 1
R304, pin 2
R304, pin 3
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
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.
Summary of Contents for 6512
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