Why won't the cash register computer all-in-one turn on?

- Jan 13, 2020-

Troubleshoot the computer won't boot and the black screen.

Many times we will encounter the problem that the computer will not start after pressing the computer's power-on button without any power-on self-test or entering the operating system, which often makes users unable to handle and affect normal use. Here we do a simple analysis of common failure phenomena, analysis and solutions, hoping to help users who encounter such problems.

No response after pressing the power button

Symptom: Nothing is displayed on the screen after power-on, and no “dropping” sound from the motherboard speakers is heard.

Failure analysis: The internal BIOS data of the main board COMS chip is damaged and damaged by CIH virus or static electricity, and cannot be read. The system cannot complete the self-test during system startup, so it cannot be started.

Known solution: Contact the motherboard manufacturer to replace the new COMS chip or find the BIOS file provided by the motherboard manufacturer and write it with the writer.

Symptom: After pressing the power-on button, the optical drive light flashes, the power indicator light on the motherboard is on, and the power supply is normal, but there is no display on the screen and there is no "dropping" sound.

Fault analysis: This phenomenon occurs after the CPU is damaged. The BIOS first checks the CPU during the self-test. The CPU cannot pass the self-test if the CPU is damaged, and the computer cannot start.

Known solutions: Check whether the CPU is installed correctly, check whether the CPU core is damaged, use the replacement method to check whether the CPU is damaged, and if the CPU is damaged, replace the CPU.

Symptoms: No display or prompt at boot, motherboard power supply is normal, CPU is normal, fan is normal, but the screen is not displayed. There is also no "dropping" sound that passes the self-test.

Troubleshooting: After using the computer for more than 3 years, the battery voltage that powers the BIOS settings gradually decreases and data cannot be saved. In some motherboards using early chipset, self-tests will not be completed, and there is no problem with the motherboard hardware.

Known solution: Purchase a CR2032 lithium battery, replace the existing battery on the motherboard to complete the self-test normally, and then reset the BIOS parameters.

Symptom: After pressing the power button, the computer will automatically shut down immediately or there will be no response.

Failure analysis: In order to protect the CPU from being dissipated by the motherboard, some motherboard manufacturers may cause the CPU to burn out. When the CPU fan is not installed or the CPU fan power cable is not connected to the motherboard CFAN interface, or the CPU fan is connected to the SFAN Fan connector), it will not turn on.

Known solution: Connect the CPU fan to the power connector of the motherboard correctly, and confirm that it is connected to the three-core dedicated CPU fan connector of the CFAN next to the CPU.

Symptom: After pressing the power-on button, the self-test fails, the display does not show, and the indicator light is orange or flashing.

Failure analysis: During the self-test process, the graphics card fails the self-test and cannot complete the detection of the basic hardware and cannot be started.

Known solution: Check if the gold finger of the graphics card is oxidized or there is a large amount of dust in the AGP interface causing a short circuit. Wipe the gold finger with an eraser, and use a skin tiger to clean the dust in the AGP interface. At the same time, use the replacement method to eliminate the problem of damaged graphics card. If the graphics card is damaged, replace the graphics card.

Symptom: The self-test is not completed after the power is turned on, no "drop" sound is heard, and a continuous "drop-drop-drop ..." sound is issued at the same time.

Failure analysis: According to the description of the BIOS alarm sound provided by the BIOS manufacturer, the problem is usually caused by the memory, and the chance of memory damage is relatively small. Most of the problems are caused by memory oxidation or poor socket contact.

Known solution: First check if there are burnt marks on the gold finger, memory slot, chip, and PCB. If there is any suggestion, replace the memory. If not, use your eraser to gently wipe the gold finger and reinsert it into the memory slot.

Symptom: After power on, the power is normal, but the NUM indicator on the keyboard does not blink. Unable to complete self-test.

Failure analysis: The keyboard controller or I / O chip of the motherboard is damaged, and the self-test cannot be completed.

Known solution: Replace the I / O chip by the manufacturer and check the keyboard interface circuit.

Symptom: Pressing the power-on button does not respond, and the power and hard disk indicators are not on.

Failure analysis: By using a multimeter to check the output voltage of the power supply, it is found that 12V 5V 3.3V are abnormal, which is very different from the standard voltage, and there is a problem with the internal circuit of the power supply.

Known solution: After replacing the high-quality 300W power supply, the problem is solved.

Symptom: Remove all parts in the case and test it normally. When it is installed in the case, it cannot be turned on. Sometimes it can be turned on normally when the case is erected. However, it cannot be turned on after being laid flat.

Failure analysis: Some chassis are not standard, resulting in deformation of some motherboards or deformation of some boards. The bottom of the motherboard is in contact with the chassis, resulting in a short circuit, which makes it impossible to boot.

Known solution: Replace the case with good quality, and install each part with standard accessories.

Symptom: After turning on the power or pressing the power-on button, the power light flashes quickly. Nothing is displayed on the screen.

Fault analysis: Sometimes, the POWER and RESET of some poor-quality cases are easily stuck inside or short-circuited internally, causing the keys to be connected all the time, repeated power-on or restart, and the illusion of being unable to power on.

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