Two Cases of Aloka SSD-5500 Ultrasound Repair

Ultrasound diagnosis has advantages such as wide application areas and no radiation accumulation, and has become an indispensable medical device in clinical diagnosis. The ALOKA SSD-5500 color Doppler diagnostic instrument (hereinafter referred to as ultrasound) has 12-bit digital acoustic imaging, 182 dB system dynamic range, high-frame-rate multiple beam processing, and enhanced pure harmonic detection (EPureHD) and other advanced technologies, and has been widely used in domestic hospitals.

The instrument suddenly crashed during use, and after restarting, it reported a "CPU error." The system could not enter the normal ultrasound diagnostic interface, and the malfunction persisted after multiple restarts.

1.2

Because the data processing platform of this machine is based on Microsoft's Windows operating system, when this malfunction occurs, the first consideration is that the CPU and hard disk drive (HDD), which are directly related to system startup, have malfunctioned.

During the restart process, it was found that the hard disk indicator light on the control panel did not flash, and there was no sound of the hard disk reading after the system started, indicating that there was no data exchange between the CPU and the hard disk. It was suspected to be a CPU malfunction. The CPU chip on the motherboard was not found to be heating up. Next, the motherboard memory stick was replaced, and each group of cables was re-plugged. After powering on, the malfunction persisted. After removing the CPU board for observation, no obvious burning or damage to components caused by insufficient heat dissipation was found. It was initially judged that the CPU motherboard was damaged.

Due to the high degree of integration of this motherboard chip, the motherboard could not be repaired. After replacing it with the same Model motherboard (number: EP521800AA), the device started normally and entered the ultrasound diagnostic interface, and the malfunction was resolved.

During the device's self-test startup, the screen displayed an error message: "Drive voltage abnormality."

2.2

According to the error message, it was suspected that the power supply circuit board was damaged. First, the power supply box was cleaned of dust, and the power supply cables were re-plugged. After powering on, the malfunction persisted.

The ultrasound power system is generally divided into digital power supply, analog power supply, and pulse power supply. The digital power supply powers the digital circuit board and computer image processing system; the analog power supply powers the circuits for receiving ultrasound pulse signals, amplification, phase control, and video amplification; the pulse power supply provides program-controlled high voltage (PHV) for the ultrasound probe's transmitting circuit, approximately 100Voc. The voltage level is related to the detection depth, resolution, and number of levels of the emitted pulses of the ultrasound equipment.

The measurement of the power supply board voltages ±5Voc, ±12Voc, +40Voe, etc., were all normal. When measuring at the TP6 measurement point, no voltage was measured, while the normal voltage should be +6Voc. After observation, when the ultrasound probe was unplugged from the device, the screen no longer displayed the error message "Drive voltage abnormality." Because the ultrasound probe requires a working voltage of about 100V for ultrasound excitation, the TP6 measurement point is actually the measurement point for the ultrasound excitation working voltage.

It was considered to use the substitution method to narrow down the fault range. After replacing the image processing board of this Model (number: EP487150BE), the malfunction was resolved.

3. Summary

For the management of ultrasound diagnostic instruments, preventive maintenance management should be strengthened first, focusing on daily maintenance and upkeep, providing the instrument with a stable power supply, paying special attention to regularly cleaning the instrument's filter screens and dust from components, maintaining the stability of the equipment's operating environment temperature and humidity, controlling the temperature to 15～33℃, humidity <90%, and leaving a 15cm gap for the equipment placement to ensure good heat dissipation. By implementing scientific and reasonable preventive maintenance measures, the occurrence of malfunctions can be reduced as much as possible, improving the utilization rate and integrity rate of ultrasound diagnostic instruments, and extending the service life of the equipment.

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