'Arduino Mega Custom Board (PCB)' does not turn on even after 5 minutes of powering on

'Arduino Mega Custom Board (PCB)' does not turn on even after 5 minutes of powering on.

Even if I don't speak English, please forgive me.

  1. I made an Arduino Mega. With your own PCB,
    (Reference link)
    https://www.instructables.com/DIY-Bare-Minimum-Arduino-Mega-2560/

  2. If the PCB is placed on the ground and power is applied, it will not turn on.
    Using the support, the PCB must be floated in the air to turn on.
    I don't know why. I want to know.

  3. When the CP2102 is connected in the PCB board, it turns on immediately. Even if the PCB is on the ground, it works just fine.
    I don't know why. I want to know.

Please help me.

Have you photos about your system, power connected and so on.
"Using the support, the PCB must be floated in the air to turn on." This could mean a short circuit below your board, or your board is broken and needs to lifted just right to work. But this is all quess work, without seeing the board.

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Is it possible you had a small piece of metal loose on the board and in the process knocked it off.

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If it's a PCB problem,

When the CP2102 is connected in the PCB board, it turns on immediately. Even if the PCB is on the ground, it works just fine.

This part is not explained.

Why does it work when I connect the CP2102 cable?

If it's a PCB problem,

When the CP2102 is connected in the PCB board, it turns on immediately. Even if the PCB is on the ground, it works just fine.

This part is not explained.

Why does it work when I connect the CP2102 cable?

@myksj, your topic has been moved to a more suitable location on the forum; not sure why you think that this relates to Avrdude, stk500 or Bootloader.

Maybe because it provides a missing ground connection?

Show your schematic and (as asked in the first reply), photos (in focus, reasonably sized) of your setup.

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Thanks.

This is picture.


Remove all power wires and so on, so that there is no power on your board, then measure all ground points with ohm meter if they are connected together. Hold the board good and bad positions. You should see some difference.
Then repeat the same with +5V.

What material is your table made of. Metal is bad here.

One more thing. What kind of power supply you have. Is it possible that it has too much noise for your board to work. Or reset does not work. Try holding the reset pin down a moment, does your board start then.