Examples of color ultrasound equipment circuit board repair

In simple terms, ultrasound is a high-definition black and white B-ultrasound combined with color Doppler. Color Doppler ultrasound generally uses autocorrelation technology for Doppler signal processing, color-coding the blood flow signal obtained by autocorrelation technology, and then superimposing it in real-time on a two-dimensional image to form a color Doppler ultrasound blood flow image. Thus, color Doppler ultrasound (i.e., ultrasound) has the advantages of two-dimensional ultrasound structural images and provides rich information on hemodynamics. It has received widespread attention and welcome in practical applications and is lauded in the clinic as "non-invasive angiography."

Meanwhile, it has irreplaceable advantages over other imaging equipment in imaging examinations of various organs in the human body, such as the liver, gallbladder, kidneys, heart, and thyroid. It is characterized by simple and convenient operation, fast examination speed, and no damage to the human body. [Company Name] has accumulated rich experience in product maintenance, repair, and imitation development through long-term reverse technology research, and has long provided the transfer of complete sets of clone and technical data for two types of medical equipment products. In this article, [Company Name]'s engineers analyze the troubleshooting and troubleshooting skills of such instruments and equipment starting from several common circuit board faults in color ultrasound equipment, providing some reference for maintenance engineers.

Fault 1:

A 525 ultrasound machine. No matter whether the abdominal probe (C314G) is working in B mode or CFM mode, radial interference lines appear on the monitor screen from time to time, sometimes two, three, or more. The positions of these interference lines on the monitor screen are also random.

Fault Analysis:

This type of fault is relatively common when the ultrasound machine is working. There are four main reasons for this type of fault:

(1) External interference (including radio interference, high-frequency treatment machines, large motors, large UPS power supplies, and electromagnetic interference generated by large medical equipment during operation);

(2) Poor AC power supply/AC voltage regulator;

(3) Deteriorated probe performance, interference between chips during operation;

(4) Circuit board fault, such as faults in the transmission/reception control board, probe interface board, etc.

Troubleshooting:

First, determine which type of fault it is. This can be done by following the steps below. Turn on the instrument during lunch breaks or at night when everyone is resting and observe whether there are any interference lines on the monitor screen; move the instrument's placement direction or change locations and turn on the power again to observe the display on the monitor screen; observe the display on the screen when the instrument is connected to and not connected to the AC voltage regulator, and measure the voltage value of the AC power supply when the instrument is working with a multimeter. If there are radial interference lines in the above steps, it can generally be determined that it is not caused by external interference or poor AC power supply. Generally, ultrasound machines have two or three probes, some with four. Commonly used are 2.5MHz cardiac probes, 3.5MHz abdominal probes, and 7.5MHz/10MHz superficial probes.

Make these probes work in B mode and CFM mode respectively. If the 2.5MHz or/7.5MHz/10MHz probe works without interference lines, it can generally be determined that the 3.5MHz abdominal probe itself is faulty and needs to be replaced. If interference lines appear when several probes work separately, it can be suspected to be a circuit board fault. If it is a circuit board fault, the suspected faulty circuit boards (such as T/R controller, probe I/O, etc.) can only be replaced one by one to troubleshoot. Through the above steps, it is determined that C314G is faulty. After replacing this probe, the machine resumes normal operation, and no interference lines appear on the monitor screen.

Fault 2:

After turning on the power of a Toshiba 140A ultrasound machine, a fault code appears on the instrument monitor screen. Pressing other keys on the keyboard does not change the monitor screen, and the instrument cannot Enter normal working state.

Fault Analysis:

Because the fault code is a long string of numbers, there is no data available to check and the fault cannot be determined. Based on the fault phenomenon analysis, the circuit boards that may have faults include: CPU board, keyboard I/O interface board, PULSER board, and T/R control board, etc. Troubleshooting: Remove the suspected faulty boards from the motherboard one by one, turn on the instrument one by one, and observe the display on the monitor screen. This instrument has two PULSER boards. When the board numbered PM30-22554 (YWA2482×C) is removed from the instrument, and the instrument's power is turned on again, the instrument undergoes self-test and initialization for a few seconds before the ultrasound echo image appears on the monitor screen, and no fault code appears. If this board is inserted into the motherboard again and the instrument is powered on, the fault phenomenon remains, indicating that this board is the faulty board.

This board has five sets of input power supplies: VH, -10V, +12V, ±5V. When measuring the resistance between the +5V input terminal (i.e., the insertion terminal connecting the board to the motherboard) on this board and the 20th pin (+5V power input pin) of the T1733 integrated circuit on the board or the 5V power input pin of other integrated circuits (such as HC240, HC164, and HC564, etc.) with a multimeter's ohmmeter ×1Ω range, the resistance is infinite, indicating that the +5V power supply is not applied to these integrated circuits, causing these integrated circuits to not work.

When the CPU in the instrument communicates with this board, it detects a fault, and the instrument stops working. Following the +5V input terminal of the board, it was found that the +5V power supply is connected in series with the inductor (LCH15) and then connected to the +5V power input pin of the integrated circuit on the board. Careful observation revealed a small crack in the middle of the inductor (LCH15). Measurement with a multimeter's ohmmeter showed that the inductor was open. An inductor was made by winding a 0.5mm diameter knee wrap wire into a 3mm outer diameter, 3-5 turns to replace the inductor. At this time, measuring the +5V power supply input terminal and the +5V power supply input pins of all integrated circuits on the board with a multimeter's ×1Ω range showed that they were all connected. However, measuring the DC resistance between +5V and ground with a multimeter's ×1Ω range showed about 1Ω, indicating a short circuit between +5V and ground.

Because the +5V terminal is connected to dozens of integrated circuits and dozens of capacitors, damage to any one component will cause a short circuit. It is also impossible to unsolder and measure each component. The faulty component was quickly discovered using the following pressurization method. First, the +5V output terminal of an independent PC power supply is connected in series with a cement resistor of approximately 2Ω. Then, the other end of the cement resistor is connected to the input terminal of the inductor (LCH15), and a multimeter (in current mode) is connected in series with the +5V power supply output terminal. After turning on the PC power supply, the multimeter indicates a current of approximately 1A. Then, quickly touch each component on the board by hand. As a result, it was found that the surface temperature of the 74AC04F integrated circuit and the chip capacitor C651 was higher. Turn off the PC power supply, unsolder the capacitor, and measure the resistance between the two ends with a multimeter, which is approximately 1Ω. Then, measure the resistance between +5V and ground with a multimeter, which is a few hundred ohms. This indicates that the capacitor is shorted, causing the inductor (LCH15) to burn out, resulting in the board not receiving +5V power and the above-mentioned fault. After replacing the capacitor with the same Model, inserting the board into the motherboard, and turning on the power, the instrument returns to normal operation.

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