When repair B ultrasound, there are lots of faults which we cann’t ensure. After detailed examination, you maybe make a judgment and do a further maintenance.

Fault phenomena

B ultrasound, the host machine work normally, frozen unit does not work and make B ultrasound image can’t freeze and can’t measure.

The freez unit is a separate device and connect with host machine. Disconnect with cable and charge freeze device alone and find no lighting of frozen device indicator, but the fan can work; Then open device shell and find that there are three parts are consist of that in unit interior: Power, Input/output substrate and memory, so you can ensure that memory boards is damaged. After preliminary examination, -5V can produce circuit on memory boards, clock frequency has circuit, buffer circuit and memory circuits. In addition, there are many small capacitances on board. Under electricity state, use multimeter to measure every test point voltage on board as following: TP12.03v, TP23.13V, TP31.45V, TP41.59v TP53.05V, TP61.98V, TP7-5V. Then replace the board and test, numerical value is the same; After that, you can use oscilloscope to observe crystals working condition, waveforms output is normal. It recoveries the possibility of causing fault of -5V producing circuit and clock circuit. But buffer, memory working state isn’t easy to ensure; The following is that spare board and check the small capacitances of the board, so use multimeter to measure and find that there are some capacitances short circuit; Then examine them in turn one by one. At last, replace the damaged one and the machine can work normally.

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