I recently got a new Raspberry Pi 3 Model B+ and I managed to flash the OS. But the problem seems to happen when I try to boot it. I do not have the official adapter, but I tried the following:

  1. with a USB to Micro USB Power supply by connecting the USB to my Mac.

  2. I had another power adapter that I was using on my mobile phones. It is rated at OUTOUT: 5V 1A

With both the options, I get a constant red light after a couple of seconds of connecting the Pi to the power source. Is this some problem with the Power source? How can I resolve this? I have tried to flash my card atleast 5 times, but to no success. I then came to the conclusion that this could be a problem with the Power source. Can anyone throw some suggestions on how I can make this work?

  • 5V at 1A is sufficient as long as there are no power-hungry USB devices. Perhaps not even a WiFi adapter. Certainly no Arduino expecting power. 2.5A would be better, in any case. I'm not sure what this question is asking. For instance, why is a couple of seconds distressing? Also, the crux: Does the thing boot? The more information you supply in your question, the better the answers it will attract. (from review) – SDsolar Apr 21 '18 at 0:01
  • You seem to think the red LED is a problem; this means voltage is OK. You CANNOT power a Pi from USB on a PC. Some just supply 5V, which should be limited to 500mA. The Mac will only supply 100mA unless a higher current is negotiated, which the Pi CANNOT. If the 1A PSU is an Apple it will run a Pi3 B+ (without peripherals). – Milliways Apr 21 '18 at 1:37
  • I'm not sure what this constant red light is about? Is it because of the Power Source? How can I verify what is going on in the Pi when I boot it up? – sparkr Apr 21 '18 at 4:04

Seems there is no problem at all with your Raspberry Pi. A constant red light, the PWR led, indicates that your raspi is properly powered up. With a bad power supply it would flash below 4,63 V. So you do not have to worry about your power supply with 1 A output. It's enough in this case. For further information look What do system LEDs signify?. With a display and keyboard attached you should see that your raspi properly boots up.

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As pointed out earlier the problem is not with the power supply. 1 A is enough to run a RPi.

Here are some ways to revive a RPi

  • Try the pin method
    sometimes the SD-card reader on the pi gets deformed over time, so applying some pressure on the SD-card with a pin or folded paper could work, also cleaning it with a brush works sometimes.
    refer to this for further explanationhow a deformed SD-card looks

  • You could try booting from an USB(assuming your USB ports are in a good shape)
    Flash a USB disk or you can just insert your SD-card into a SD-card reader
    Since you are using a RPi-3b+ you only need to write
    In config.txt then try booting.

    If it doesn't work(USB disk doesn't get powered) then measure the voltage between PP-2 and PP-27 or PP-7 and PP-27 ideally it should be around 5V if it isn't then you could connect PP-2 and PP-27 like this guy or you could replace C97 and U13 like done over here.


    if USB does get powered but you cant boot then either
    the Device is not supported or
    the the Device takes longer than 2 second to power up or respond.

    Here are some supported USB Drives
  • Sandisk Cruzer Fit 16GB
  • Sandisk Cruzer Blade 16Gb
  • Samsung 32GB USB 3.0 drive
  • MeCo 16GB USB 3.0

    If you are not using one of these its still okay since there is a good chance that your USB is supported.

  • If all fails
    If Nothing works then probably your RPi is RIP, if it is really dead then it will not read any MSD(Mass Storage Device) give any HDMI output and have a cold Soc,some 5V GPIO sources may work, like for a fan.
    If your pi isn't cold then there is some is some CPU activity but no storage to read so in this case you should replace the SD-card slot or USB slots however its risky and might damage your pi, though it is worth a try since a working pi is better than a dead one.

Conclusion: you must remember that a RPi is a small computer the size of a credit card for $35 not some super-expensive gaming rig, if it is dead then toss into a bin or replace it. Don't waste your time tinkering with a Expensive red LED.

Hope this helps!

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Buy a better power source. The recommendation is that a Raspberry Pi 3 B+ needs a power source rated for 5V at 2.5A so one that is only going to output 1A is definitely not enough. Standard USB ports only provide 500mA (USB 2) or 900mA (USB 3).

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  • 3
    You DEFINITELY CAN run a Pi3B+ with a decent 1A supply - I do it regularly. Just don't expect to power any peripherals. Of course most PSU are NOT decent, and the cables are even worse. See Raspberry Pi Power Limitations – Milliways Apr 21 '18 at 1:41

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