Fukuda Denshi CARDIMAX FX-7202, Service Manual

Page: 43 / 160

Maintenance
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Safety inspections (6 items)
Safety-related testing methods and measurement equipment are prescribed
in safety test standards. At the actual sites where medical treatment is being
given, however, it can be extremely difficult to verify that everything meets
the standards. For this reason, when performing inspections, set up and
make acceptance determinations using the methods described below.
WARNING
If, during a safety inspection, a value that exceeds the allowable limit is
confirmed, immediately stop using the given unit; then replace the
defective part or make proper repairs. Failure to repair the unit can lead to
a serious accident.
Before checking the leakage current
There are a number of conditions for measuring leak current. For the
measured values, however, use the maximum values that are obtained.
When checking, it is also important to make comparisons with past
measured values to confirm that there are no large differences.
To measure the leakage current, use leakage current gauges (electronic
voltmeters and digital voltmeters), impedance for measurement, power
switch box, and similar equipment.
Impedance for measurement
The impedance will have a structure such as that shown below.
R1
R2
C1
V
R1 :10k ± 5% (No lead)
R2 :1k ± 1% (No lead)
C1 :0.015µF ± 5% (No lead)
V :Voltmeter
By measuring the voltage at both ends of the impedance, you can find the
leakage current.
Voltmeter
Because digital voltmeters are required to indicate true effective values for
composite waveform from DC to 1 MHz, it is recommended that you use a
voltmeter whose performance meets the prescribed standard as closely as
possible.
For use during maintenance and inspection in the field, you can use a
commercially available digital voltmeter instead. However, check the
frequency band of the voltmeter you plan to use ahead of time. To measure
a leakage current that exceeds the measurable frequency band, use it with
care paying attention to the indication on the voltmeter.