Three Cases of Troubleshooting and Repairing the Mindray DC-8 Color Ultrasound Diagnostic System

Malfunction 1

1.1 Malfunction Phenomenon

After the device was normally powered on and started, there was no image in the middle part of the probe's synchronous area. After multiple attempts of unplugging and replugging the probe and restarting the device, the malfunction remained unchanged, and there were no prompts or error messages.

1.2 Malfunction Analysis and Troubleshooting

Based on the malfunction phenomenon and personal repair experience, judgment was made using the following methods:
First, the probe was replaced to other slots, and the malfunction phenomenon remained the same, thus excluding the probe slot malfunction. Then, it was checked whether other probes also had missing images. It was found that the middle part of the image of a convex array probe was completely missing, and two parts of the image of a linear array probe were missing. Since the probability of two probes malfunctioning simultaneously is extremely low, probe malfunction can be basically ruled out.
Second, based on the malfunction phenomenon, it may be caused by the malfunction of the ultrasonic transmitting board, the ultrasonic receiving board, and the image signal processing board. However, it is difficult to determine which board caused the malfunction. The self-test function of the ultrasonic device can be used for auxiliary detection and judgment. Click the "Maintenance" item in the "Preset" menu, open the "Maintenance" menu, click "Self-test" to perform a system self-test. The self-test reported a signal processing board error. After replacing the signal processing board, the device returned to normal.

Malfunction 2

2.1 Malfunction Phenomenon

Using an abdominal convex array probe on the DC-8, unclear white-spot interference appeared in both Color and B modes. At the same time, it was found that when the hand touched the probe, the interference would be significantly stronger and unevenly distributed. Using other probes for exchange testing revealed no interference. The interference may be caused by unreliable power grids and ground wires.

2.2 Malfunction Analysis and Troubleshooting

Due to the high sensitivity of the ultrasonic device probe and the wide frequency band of the whole machine circuit, the ultrasonic device is very susceptible to various power or electromagnetic field interferences during use.

Based on experience, the common ways that external interference enters the ultrasonic device are as follows: First, it is introduced through the probe, poorly shielded cables, connectors, and the casing; second, it is introduced through the power grid. The interference source can be found using the elimination method.

First, other electrical appliances sharing the same socket with the DC-8 ultrasonic device were unplugged, and it was powered on individually. The interference source weakened, but still existed. After connecting a reliable ground wire, the interference was significantly reduced. After moving the device to another department in a distant location, it was found that the interference was completely eliminated. Based on the above phenomena, it can be basically confirmed that the interference was introduced into the device through the probe and casing from the spatial interference.

Secondly, all electrical equipment in the ultrasound department, including servers, workstations, air conditioners, fans, dehumidifiers, and fluorescent lights, were checked one by one by turning them off. During the check, it is necessary to unplug the power cord supplying power to the device to ensure that the device is completely shut down, because some devices still have components working after turning off the device switch. After thoroughly checking the power supply of all electrical equipment in the ultrasound department, there was no sign of the interference being eliminated.

Finally, considering that there were many and disorderly electrical equipment around the ultrasound department, the same method was used to check the electrical equipment in the surrounding departments. It was eventually discovered that the fluorescent lights used for lighting in the adjacent department were causing interference to the device. After turning off the fluorescent lights, the interference disappeared. Finally, the fluorescent lights with the same Model were replaced in the ultrasound department, and the device returned to normal use.

Malfunction 3

3.1 Malfunction Phenomenon

The operating physician reported that while collecting images from patients, the device suddenly lost power and shut down, and then could no longer be started. Apart from this, there were no other abnormal phenomena, such as sparks or a burning smell. During on-site inspection, it was found that: When the AC power was connected, the AC indicator light was on normally. After pressing the power button, the AC indicator light was normally on, and the power key indicator light was normally on, but the hard disk indicator light did not respond. The monitor indicator light first turned green, then off, and then orange. Checking the power indicator lights on the back of the device showed that after powering on, the 12V indicator light was on, while the 5V and 3.3V indicator lights were off.

3.2 Malfunction Analysis and Troubleshooting

Based on the phenomenon and repair experience, it was initially judged as a power module malfunction, so an attempt was made to replace the power module circuit board to confirm the cause of the malfunction. Since there was another DC-8 ultrasound device that was working normally, parts could be exchanged to help find the problem. However, after replacing the board, it was found that replacing the AC-DC power module and the power board could not solve the malfunction, and the malfunction phenomenon after replacing the circuit board was exactly the same as before, thus ruling out power module malfunction. Later, the system was minimized to troubleshoot the malfunction. The front casing and connecting board of the device were removed, and the motherboard cables were unplugged. Only the power input cable, monitor power cable, signal cable, and control panel signal cable were left. Under this condition, the machine started normally. Then, other power cables were plugged in one by one. It was found that when the control panel power cable was plugged in, the device could not start, indicating that an internal short circuit on the control panel caused the malfunction, resulting in the power module not outputting +5V and 3.3V, and the whole machine could not start normally. After replacing the internal components of the control panel, the device returned to normal.

Summary

Mindray DC-8 color ultrasonic diagnostic instrument, as a high-performance flagship product of Mindray Company, plays an increasingly important role in hospital clinical medical work. Through the analysis and solution of the 3 malfunctions of the DC-8 mentioned above, we can better understand the working principle, structural composition, and potential malfunction risks of the machine during use. This improves the repair ability of maintenance personnel, saves a lot of costs for hospitals to a certain extent, and prolongs the service life of the machine. It can also provide repair ideas for other colleagues when encountering similar problems. At the same time, as an important tool for auxiliary examination in hospitals, daily maintenance should be strictly carried out in accordance with relevant requirements, ensuring normal and stable power supply of the equipment, the temperature and humidity of the working environment meet the requirements, the grounding resistance meets the requirements, strictly operate in accordance with the equipment usage requirements, regularly maintain the probe, and dust the whole machine, to maintain the good operation of the equipment and prolong the service life of the machine.

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