GE LIGIQ Ultrasound Repair and Maintenance

1. Failure Case Analysis

1.1 Failure Case —

(1) Failure PhenomenonThe failure occurred during the first power-on in the morning. The machine powered on normally and could switch probes normally, then the failure occurred. The clipboard became larger, the set and run keys in the lower right corner of the display kept flashing, the buttons and the touch screen were unresponsive. Pressing the power-off button popped up a system unresponsive display box, and it could not be selected via the touch screen or mouse, only the left and right keys could be used for selection. Restarting or ignoring shutdown could not be selected, then it entered a white interface with a logo, and forced shutdown was unresponsive. Finally, only the power could be unplugged. After restarting, it was normal.
The failure occurred intermittently. Sometimes it occurred for two consecutive days, sometimes it occurred every two weeks. The failures all occurred after the first power-on in the morning; the machine started normally at other times.

(2) Failure Analysis and TroubleshootingThe error log was copied out, and the CSD test was entered. The tests all passed. The front-end and back-end connection lines were checked, and the front-end and back-end hardware were unplugged and plugged in. The software and settings were backed up, and the system was reinstalled. The touch screen and trackball were replaced. According to the error log, a large number of trackball and touch screen errors were found. Relevant logs were searched for according to the failure time, but there were no relevant error records during the failure period. After careful verification, many infos about TrballBut and TouchPush were found at the failure time point. Combined with the fact that the trackball's set and run keys in the lower right corner of the display kept flashing during the failure, the location of the failure could be determined. The machine kept responding to the trackball and Touchpanel, causing a crash. It was just that it was not treated as an error in the error log, so the failure was resolved after replacing the trackball and touch screen. By analyzing the OP Panel schematic diagram in the manual, it can be known that the touch screen and trackball are both connected to a 5V USB Hub on the Maincontrol board of the operation panel. Therefore, the USB Hub may have caused the failure.

1.2 Failure Case Two

(1) Failure Phenomenon.Since the machine was installed, the machine has repeatedly failed to start. It can be restored to normal by restarting the machine multiple times.

(2) Failure Analysis and Troubleshooting.First, check that the mains power supply is normal. The machine standby light is on (yellow). Attempt to power on, but it fails to power on, and there is no sound of the cooling fan rotating.

Open the case, disconnect the front-end and back-end signals, supply power to the back-end separately, and observe the back-end status. It was found that there was no response after pressing the power button. Turn off the back-end power switch, wait 3s, then turn it on. The power fan and CPU fan rotate for 1-2s and then suddenly stop, still unable to power on. Wiping the memory stick is also ineffective.
Remove the plug-ins on the motherboard (including the graphics card, acquisition card, optical drive, and hard disk, etc.), leaving only the power supply and start plug, forming a minimized startup device. After restarting the back-end power supply, the result is the same, without any changes. This indicates that the failure is in the back-end motherboard.
Remove the CPU and memory power supply plugs (4-pin 12V) on the motherboard. Turn on the power supply again, and the power and CPU fans rotate normally, indicating that the back-end power supply has no problem. After reinstalling the CPU, it is ineffective. Remove the motherboard and observe the power supply circuit (capacitors, chips, etc.) near the CPU. There is no bulging, leakage, or burning marks.
Remove the motherboard battery to discharge the COMS, reinstall the battery, plug in the 4-pin power supply plug, the fan rotates normally, is no longer protected, and the machine can start. But after shutting down again, it cannot start again. After discharging the COMS again, it can start again. Connect all the loads on the motherboard (including the front-end and back-end connections). Discharge the COMS before powering on, turn on the machine, and the startup is normal. After startup, the system will report time errors, etc., which is caused by the COMS restoring to the original settings, and it can normally Enter the ultrasound application software and operate normally.

This failure is a back-end motherboard failure, unrelated to the CPU, memory, etc. It can be started after discharging the COMS, indicating that there is a problem with the motherboard hardware.
The main reason for this is that the motherboard has an automatic detection function. When the CPU or power fan speed, voltage, or temperature of various accessories is abnormal, the motherboard will automatically take protective measures, resulting in the system being unable to start. After discharging the CMOS, the various parameter settings are restored to the initial state, and the system can start normally. The failure point of this motherboard is most likely the COMs chip or the quality problem of the south bridge chip. This method belongs to the "elimination method". When there are no replaceable spare parts, it has a certain effect on judging machine failures, but it should be applied flexibly according to the specific situation.

1.3 Failure Case Three

（1) Failure Phenomenon.No display on power-on, unable to power on. After unplugging the BIOS battery, the power-on is normal, but once the BIOS battery is plugged in, it can only start normally for the first time, and then it cannot start again.

(2) Failure Analysis and Troubleshooting.Multiple new BIOS batteries were replaced (the measured voltage is around 3.1V, and the power is sufficient), but the failure remained, ruling out the BIOS battery problem. The GE default BIOS settings were loaded, and the failure remained after restarting. The voltage values of various measurement points were measured to be normal. The software was reinstalled, and the failure remained, ruling out the software problem. Various loads were replugged, and the failure remained. After replacing the new SBC board, the failure remained. At this time, the troubleshooting was stuck. After carefully checking the connection lines on the motherboard, it was found that there was a loose connection between the Power on connector (green and black lines) and the connector. After processing, the power-on was normal.

After the motherboard is powered on, the system first uses the Power on self-test (POST) program to check various internal devices. The POST self-test process is roughly as follows: Power on — CPU — ROM — BIOS — System Clock — DMA — 64 KB RAM — IRQ — Graphics card, etc. The process before detecting the graphics card is called the key component test. If there is a problem with the key components, the computer will be in a suspended state, which is usually called a core failure. Therefore, this failure occurred in the core failure part.
When the start button (power switch) is pressed, the control of the system is handed over to the BIOS. Because the voltage is not stable at this time, the motherboard control chipset will send and maintain a Reset signal to the CPU to initialize the CPU and wait for the POWER GOOD signal (power ready signal) from the power supply.
When the power supply starts to provide stable power (the process from unstable to stable is only a short moment), the chipset will remove the Reset signal (if the Reset button on the computer panel is manually pressed to restart the machine, the chipset will remove the Reset signal when the button is released). The CPU immediately starts executing instructions from Address FEFFOH. This Address is within the Address range of the system BIOS. Whether it is Award BIOS or AMI BIOS, only a jump instruction is placed here, jumping to the real startup code in the system BIOS.
This indicates that the fault lies in the CPU RESET signal not being cleared, specifically, the POWER GOOD signal not returning, causing the device to hang. As for why it can boot without a battery but not with one, this needs to be analyzed based on the different power-on circuits of various motherboards. Some motherboards use the +3V from the CMOS battery as part of the power-on circuit; however, since the motherboard's circuit diagram is unavailable in the manual, it will not be analyzed here.

1.4 Case Study Four

(1) Failure PhenomenonThe machine occasionally freezes, and this problem has recurred repeatedly after six months of use. After pressing the power button, the fan spins and then stops; pressing it again results in the same phenomenon, until the 10th attempt, when it finally starts up.

(2) Failure Analysis and Troubleshooting.Short-circuiting the poweron pins on the motherboard directly yielded no response. This rules out problems with the control panel and RTB power-on circuits. The RTN output voltage was measured as normal, indicating that the RTP input is normal. To rule out problems with the motherboard itself, an external ATX power supply was connected and tested. The workstation's ATX power supply was removed, the machine was connected, and the red and white wires removed from the RTB were short-circuited. The machine's rear end powered on, but with a long beep alarm.
It was suspected that the lack of a graphics card power connector on the ATX power supply caused a graphics card alarm, so the graphics card was removed, and the motherboard was able to boot. After removing the graphics card, a burnt smell was detected, but no obvious burn marks were visible. Replacing the graphics card and RTP did not resolve the issue.
It was suspected that the RTP was DOA. After installing the original RTP, everything worked normally. The RTP provides 5V and 12V power to the graphics card; it is possible that a short circuit in the graphics card caused the RTP to self-protect. The burnt smell from the graphics card suggests that removing the graphics card to test whether the machine can boot normally would have made the repair process smoother.

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