Fault case：Philips HD15 Ultrasound System
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Update time : 2021-03-19 13:50:53
The HD15 ultrasound cannot be turned on. After pressing the power button, HD15 cannot start normally. Check the equipment failure, and find that the host starts and then stops when starting up, and the display is blank.
First check the power supply, the wall socket voltage is normal, and the voltage entering the main power supply of the device is also normal. Make sure that the fault lies in the HD15 device itself.
The power supply principle of HD15 is that AC current passes through the main power supply of the equipment and then enters the ATX power supply at the back end. After the ATX power supply receives the power-on signal, it passes the electricity to the PC motherboard, and the PC motherboard passes the electricity to the back-end ACB circuit through the front and rear interface boards and cables. Then the ACB circuit board will transmit the trigger signal back to the main power supply. After the main power supply receives the trigger signal, the display and the front end are finally activated, and the entire device can operate normally.
According to the power supply principle of HD15, the ATX power supply at the back end starts normally after booting, but it stops and the display is black. It is judged that the device has not been fully started. At this time, the problems of ATX power supply and trigger signal switch can be ruled out. Consider the following problems. aspect:
① The interface board and connection of the back-end PC are faulty;
② There is a problem with the front-end circuit board, and the trigger signal cannot be transmitted to the main power supply;
③ The main power supply and accessories are problematic, and the trigger signal cannot trigger the main power supply.
Check that the interface board and wiring are normal, no looseness or damage; connect the NPOWER ON pin on the front circuit board to the metal casing of the device, force the power supply to operate, and the fault still exists.
After troubleshooting the first two problems, it was determined that the fault should lie in the main power supply and accessories. Therefore, the main power supply of the HD15 device was disassembled, and the appearance of the components on the power board was carefully checked. At this time, a slight bulging phenomenon was found in a capacitor It is suspected that the capacitor is the cause of the failure. After removing the capacitor and measuring with a multimeter, it is found that the capacitor is abnormally charged and discharged. After replacing the capacitor with the same specification and re-welding, the test main power supply is normal, and the equipment failure is repaired.