Fukuda Denshi FX-7302, Руководство по обслуживанию

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Chapter 2
2 - 34
Inspection of electrical performance/characteristics
1.Sensitivity
(1) Check that the recorded amplitude is within 10
±
0.2 mm after 1 mV
of voltage is added to the unit by the standard voltage generator.
The [1mV] key signal, which is an internal signal, is not appropriate to
be used for sensitivity inspection.
(2)
Change the sensitivity selector switch to 1/2, 1/4, and 2, and check
that standard sensitivity is within
±
5%.
2.Time constant
Apply 1 mV of standard voltage and check that it takes from 3.2 to 3.84
seconds for the amplitude (of the wave 3.2 seconds after dropping
exponentially) to reach 37% of the amplitude obtained after the standard
voltage is added (after 0.04 seconds).
3.Frequency characteristics
Using a sine wave generator, add sine wave voltage to the input of the
Electrocardiograph via 27 k
Ω
of resistance.
Equating 100% to a 10-mm amplitude at 10 Hz for the test voltage, check
that 0.14 Hz to 75 Hz is at least 90%, 150 Hz is at least 70%, and 0.05 Hz
to 150 Hz is within the range of 70% to 105%.
4. Common mode rejection
In the measurement circuit shown below, set the sensitivity to 2, open S1,
and close the other switches; then, while switching the lead, record the
fluctuation. Repeat this until Sn, measure the maximum fluctuation, and
check that the fluctuation on the recording paper is 4.0 mmp-p or less.
R
R
R
R
Sine wave
generator
for testing
(20Vrms)
100p
Ground potential
C1
C2
Electro-
cardiography
C
C
C
C
S1
S2
Sn
R
L
N
C6
F
C1
Protective shield
R=51K Ω
C=0.047pF
C1+C2=100pF
NOTE