The veterinary B-ultrasound has a fault phenomenon. After turning on the machine, the machine enters the veterinary B-ultrasound system normally, but there is no ultrasound image displayed in the ultrasound display area.

Carefully observe the fault phenomenon and find that there is a noise signal in the veterinary B-ultrasound image area. The gain can be adjusted accordingly and the image can be amplified normally. It can be judged that the problem lies before the beam synthesis of the ultrasonic signal, that is, the transmission and receiving part of the ultrasonic wave of the 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 for judgment is that the ultrasonic probe makes a buzzing sound, which shows that the ultrasonic probe is indeed working. Since there is no problem with the transmitting part, we will focus on the receiving part of the ultrasonic signal.

The reception of the ultrasonic signal of the veterinary B-ultrasound system is to amplify the ultrasonic signal received by the probe through the operational amplifier circuit and send it to the beam synthesis part. This fault is obviously that the beam synthesis part cannot receive the ultrasonic echo signal. After determining the fault location, we turned on the machine and found that there were 2 circuit boards at the front end of the machine, one was the TX board (transmitter board) and the other was the RX board (receiver board). Obviously, it should be caused by a fault in the RX board.

To troubleshoot the image fault in the veterinary B-ultrasound, remove the RX board and use a multimeter to measure the impedance of each voltage group to the ground. It was found that the impedance of -5V to the ground was only 4Ω, so it was determined that 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 MT8 816 was damaged. After replacing the IC of the same model and restarting the machine, the veterinary B-ultrasound image was restored and the machine worked normally.

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