There was a malfunction in veterinary B-ultrasound. After starting up, the machine entered the veterinary B-ultrasound system normally, but there was no ultrasonic image display in the ultrasonic display area.

After careful observation of the fault phenomenon, it is found that there is noise signal in the ultrasonic image area of veterinary B-ultrasound, and the adjustment gain can be changed accordingly and the image can be enlarged normally. It can be judged that the problem is before the beam synthesis of ultrasonic signal, that is, the transmitting and receiving part of ultrasonic wave of veterinary B-ultrasound system.

According to this idea, it was also found in the observation that although there was no ultrasonic image signal, the veterinary B-ultrasound probe was still working. The basis of the judgment is that the ultrasonic probe emits a buzzing sound, which indicates that the ultrasonic probe is indeed working. Since the transmitting part is no problem, we will focus on the inspection site locked in the receiving part of the ultrasonic signal.

The ultrasonic signal received by the veterinary B-ultrasound system is amplified by the operation amplifier circuit and sent to the beam synthesizing part. The fault is obvious that the beam synthesis part can not receive the ultrasonic echo signal. After determining the fault location, we opened the machine and found that the front end of the machine has two circuit boards, one is TX board (transmitting board), the other is RX board (receiving board). Obviously, it must be caused by a fault in the RX board.

The image fault was removed in animal B-ultrasound. The RX board was removed and the ground impedance of each group of voltages was measured with a multimeter. It was found that the ground impedance of -5V was only 4Ω, so there was a problem with the -5V circuit. So we eliminated the relevant components one by one, removed the components related to -5V and measured the impedance one by one, and found that an IC model MT8816 was damaged. After replacing the IC of the same model and restarting the machine, the B-ultrasound image of the animal was restored and the machine worked normally.

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