DUS 60 Digital Ultrasonic Diagnostic Imaging System Service Manual
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is too obvious (≥10%), when seriously, it can cause instantaneous malfunction.
Factitious malfunction caused by low responsibility of not maintaining in time or properly.
The device should be checked or maintained by the technicians to settle the malfunction, and
the followings are the brief introduction of basal step and method of maintenance.
There are four steps to check the malfunctions: observation, reason analysis, isolating
malfunction and eliminating malfunction.
6.5.1. Observation
The observation is to observe phenomena and to get to know the case. There must be something
abnormal when malfunction exists. Observing all kinds of normal and abnormal phenomenon to
offer proof for analyzing and judging malfunction. The overall and accurate knowledge for the
malfunction phenomenon will directly influence eliminating malfunction and the speed. Only
know the malfunction phenomenon accurately can you verdict the reason of the malfunction
correctly. It is not allowed to switch on repeatedly under some conditions. Even if the repeated
switching on is allowed, it is necessary to know the course of malfunction and the malfunction
phenomenon from the operator, because it is helpful to judge the malfunction part and reason, it
can reduce many unnecessary course for checking and examination.
If you are not familiar with the machine to be repaired, the scope for knowing should be wider,
such as the using period, the malfunction happened suddenly or accumulatively, the malfunction
is usual or occasional, whether it ever be checked, what parts have been changed, whether the
adjustable components of circuit has been changed etc.
If the device is new, then the malfunction is always occasional, such as the vibrating during the
shipment lead to the failure of plug-in package, or the malfunction because of the weak welding
of some single components. This type of malfunction can be eliminated through careful
adjustment or fixing the loose plug-in package. If the device has been used for many years,
always happen wasting malfunction. This mainly means that the deter operation of the circuit
components such as the capacity of the capacitance especially the electrolytic capacitance go to
decline, leakage even invalidation, the change of impedance, all kinds of transformer and loops
are affected with damp and went moldy, the damage of transistors and semiconductor integrated
circuit etc. This kind of malfunction must be analyzed carefully to be found.
6.5.2. Reason Analysis
Reason analysis is to analyze and define the reason of malfunction to offer theory instruction for
further isolating and finding the concrete parts existing malfunction. It is dangerous to start
working without analysis, especially for the complicated device. The same malfunction maybe
caused by different reasons, though PCB of B-mode ultrasound are soldered carefully, it is
difficult to disassemble the components, repeated soldering will lead to the injury of circuit and
components, even worsen the malfunction. Reason analysis should be based on observation,
analysis and abundant technical knowledge. The correct conclusion can only be got from
comprehensive consideration according to the operating principles of circuit, structure features
and the rule of malfunction. Firstly, all the possible reasons should be analyzed to confirm which
are the most possible and which are the less possible to cause the malfunction. After that the most
possible reasons will be checked to find the exact malfunction parts.
6.5.3. Isolating Malfunction
Isolating malfunction is to find the exact malfunction circuit and components through a certain
checking and examination. There are many ways to isolate malfunction, and will be introduced in
details. Isolating malfunction is base on the comprehension to the conditions and operating
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