Ultrasound power supply fault repair

Ultrasound machines inevitably encounter malfunctions during prolonged operation. These malfunctions can lead to severe consequences and delays in patient treatment. Below, we will discuss how to repair power supply issues in ultrasound machines.

The power supply for an ultrasound machine is not like that of a typical electronic product. It requires high standards of data accuracy, precision, and stability. Therefore, its quality is particularly important: anti-interference, stability, power, and a complete set of electrical safety factors are all superior to other electronic products. This necessitates complex and intricate circuitry. Let's use the example of repairing a Fanfan ultrasound power supply to simplify and understand its complex ultrasound power supply circuit.

The 220V AC mains power passes through a noise filter. This filter removes high-frequency noise from the power supply. After rectification and filtering, a 300V DC voltage is obtained and divided into three paths: ① It is converted to approximately 110VAC using a DC/AC converter circuit to supply the PC and monitor. ② It supplies the PWM (Pulse Width Modulation) and PS-ON control circuits, combining with the power switch to control and adjust the switching circuit through power detection. ③ 300V passes through a push-pull switching circuit and a high-frequency switching transformer to the output circuit. Some even have an output transformer. Voltages such as +3.3V, ±5V, -5.3V, +11V, ±12(15)V, +60V, -140V are generated. Different models have different voltage parameters, while the high-voltage part is around ±100V--140V. For specific parameters of different brands and models, refer to the TEST points on the machine. This completes the entire power supply processing flow.

By simply dividing the functions, we can clearly analyze where the fault lies. We can check if the machine powers on, if the display shows anything, if the PC works normally, if there is output at ±3V, +5V, ±12(15)V, if there is a short circuit in the load, if there is high voltage after powering on, if the sampling protection circuit is working normally, if the PWM components have normal operating voltage, and if there is adjustment output. By combining methods such as using an oscilloscope, multimeter, external power supply, isolation method, and static measurement, successful ultrasound power supply repair is within reach.

There are countless malfunctions in ultrasound power supplies, and equally diverse repair methods. However, the highest level of skill lies in applying what you've learned to new situations.

Furthermore, the ultrasound power supply flow can be divided by load into: ① Supply to the digital processing circuit: for digital circuits and digital scan converters, mainly for computer image processing systems. The main voltage parameters are ±3V, +5V, ±12(15)V. This group has a relatively large load, so the required current and power are relatively large. ② Supply to the analog circuit: used to supply the ultrasound pulse amplification, phase, detection, and video amplification circuits for operational functions. The main voltage parameters are +5V, ±12V, etc. ③ Supply to the pulse circuit power supply: used to supply high voltage to the probe's transmitting circuit. The high voltage affects the detection depth and resolution. The main voltage parameters are approximately ±100V to ±130V.  

When repairing an ultrasound power supply, you can identify the fault location based on the three different functions above. By being bold, careful, and clear in your thinking, overcoming the complexities of ultrasound power supply repair will not be a problem.

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