How to repair a 'dead' GE Siemens Aloca ultrasound machine?

The "freeze" failures of GE Siemens Aloka and other ultrasound equipment are similar to the "freeze" failures often encountered in computers. Sometimes, turning the machine off and then on again will restore normal operation. However, sometimes the "freeze" phenomenon cannot be eliminated by any emergency measures. In such cases, professional GE Siemens Aloka ultrasound repair personnel should be contacted.

Fault Phenomenon 1:Power-on self-test fails, and the machine cannot start.。

After opening the front cover of the machine and applying power, the DC operating voltage is measured. The VP2 voltage is +3.8V, while the normal value is VP2 = +5V. Because this power supply is related to the ultrasound front-end board and channel board, the probe is unplugged and the machine is powered on again, but it still fails to start. Checking the machine's front-end channel boards CB0-CB8 (eight in total), four of them are unplugged, and the machine powers on and self-test passes, detecting VP2 = +5V unchanged. When more than five front-end channel boards are restored, the machine is started, and the VP2 voltage is below 4.5V, sometimes as low as 4.3V, the machine's self-test fails, and a "freeze" fault occurs.

Analysis of the cause: Is the "freeze" problem caused by poor load capacity of the VP2 DC +5V power supply?

Contacting Philips manufacturer, borrowing a new power supply box, testing VP2 = +5V unchanged, the machine self-test passes, works normally, and the "freeze" fault is eliminated. Therefore, it is considered that this fault is caused by poor load capacity of the VP2 power supply, causing a large voltage drop of the +5V power supply during power-on, which leads to power-on self-test failure and a "freeze" fault.

 Fault Phenomenon 2: Image "freeze", operation keys unusable.

After turning off and then on again, the machine fails to start, and the monitor screen is "gray", i.e., there is no display.

Using the ultrasound maintenance backup boot disk cannot eliminate the "freeze" fault.

Checking all DC operating voltages inside the machine, all are normal. Suspecting machine software failure, but when reinstalling the machine software, it always stops halfway through the installation and does not proceed, so it cannot solve the "freeze" problem. Finally, the machine's motherboard was checked, and after checking by replacement, it was found that the memory stick on the motherboard had a problem, and after replacing a memory stick, the machine's "freeze" fault was eliminated.

The machine's self-test and operation are normal after power-on. The cause of the "freeze" fault is damage to the motherboard memory stick.

Summary: This repair experience tells us that sometimes dealing with "freeze" problems requires more comprehensive and even complex thinking.

Fault Phenomenon 3: The machine frequently freezes irregularly during normal operation.。

Sometimes, turning off the machine and restarting it restores normal operation. However, sometimes when restarting the machine, it still freezes. Sometimes when the "freeze" fault occurs, waiting for a while allows the machine to automatically recover to normal.

Initially, the problem was considered to be complex, and measures were taken in areas of suspicion, but none could eliminate the "freeze" fault. Later, during random observation, it was found that during normal operation, the machine "freezes" the image. After measurement, pressing the freeze button again to release the "frozen" image, but the machine cannot return to the real-time check state. Several experiments showed that after the image freezes and the necessary measurements are taken, further operation checks cannot be performed, so it is suspected that there is a problem with the machine's freeze button.

Opening the cover for inspection revealed that the machine's freeze button, due to frequent operation, had cracks in the phosphor bronze片 of the button, causing a change in the elasticity of the button switch. During normal machine operation, pressing the freeze button closes the switch, the image freezes, and releasing the button should immediately open the switch for other operations. However, due to the crack in the phosphor bronze片 of this switch and insufficient elasticity, when the external force on the button switch is released, the contact point does not immediately bounce open, but bounces open very slowly. The time taken for this bounce-open process is sometimes short and sometimes long, and during this time, other function keys are unusable, resulting in a "freeze" fault.

Solution:Due to cracks in the phosphor bronze片 of the switch and poor switch bounce, the switch can no longer be used. Because this switch is quite special and cannot be purchased on the market, a less frequently used switch was found from another position on the keyboard and replaced. Since then, the machine's "freeze" fault has never reappeared.

This information is sourced from the internet. Please contact us for removal if there is any infringement.