Table of Contents
Advertisement
SECTION 3
SERVICING INFORMATION
3.1 RECOMMENDED TEST EQUIPMENT
The recommended test equipment for calibration and performance verification
is given in Table 3, Test equipment other than recommended may be
substituted if specifications at least equal those given in Table 3.
Table 3. Recommended Test Equipment
ltem
Description
Specifications
Mfg.
Model
A
DMM
10µV resolution
Keithley
195
B
Voltage Source
100V DC
Keithley
230
C
Electrometer
1 µA resolution
Keithley
614
D
Scanner Mainframe
-
Keithley
705
3.2 CALIBRATION PROCEDURES
To calibrate the Model 7057A do the following procedure:
1. Remove the green wire on the Model 7057A
2. Connect DMM across R104 (6.151k(l resistor).
3. Adjust R101 for 175.92mV ±0. lmV.
4. Remove DMM and reconnect the green wire.
3.3 TEST OF CALIBRATION
Using RFL industries ail bath {or equivalent), submerge thermistor (on 7057A)
with temperature standard measuring device {Thermometrics S-10 probe or
equivalent) into the
oil. Allow
to stabilize and note the difference
(at
30°C).
The difference should be less than .2°C.
3.4 CHANNEL ISOLATION
A. Thls test
measures
the leakage resistance between two channels on the
board. One channel is to be open and the other closed. Set up the test cir-
cuit
shown in Figure
7.
8. Short the HI and LO connections
of
each channel on the Model 7057A. Do
not connect the channels together, just short the H! and LO terminals.
C. Sat the Model 705 to the Channel mode, Channel 2 and the Step mode.
Set the electrometer to Amps and program the Model 230 to output 100V.
Take the electrometer out of ZERO CHECK. Program the channel under
test as open and other channels as closed.
D.Take the reading on the electrometer. The reading should be less than
1 x 10-6A. Using Ohm's Law calculate the channel isolation. For example:
R
~
E/1
~
100V / 1 x 10-£A
~
1 x 108(). Due to the capacitance of the cir-
cuit, the offset current may be high until the capacitance of the circuit is
charged up. Wait until the readings se-ttle out.
E. Manually scan through channels 2 through 10 repeating step C and D for
each channel.
NOTE
Channel 1 ls the temperature reference channel.
21
Advertisement
Table of Contents
