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Related

Pi PWR off but others are on

wcypierre

Not sure if it is related (http://www.element14.com/community/message/171207/l/re-pi-wont-boot-with-noise-and-pwr-lit-only#171207), but it seems that another pi of mine is down too.

 

PWR is off, but the others like ACT, ethernet are all on. Any clues on what is going on?

  • I assume this is another RasPi B+ like the other one.  First-generation RasPi Model B had a very simple power LED that was driven directly by 3.3V through a resistor, so if 3.3V was a little low the LED still came on.  The Model B+ Power LED is also driven by 3.3V, but also has a precision reset circuit that turns off the Power LED if 5V falls below a threshold.  It may be power supply issue: see the RasPi Troubleshooting Wiki: http://elinux.org/R-Pi_Troubleshooting#Troubleshooting_power_problems

     

    It will be a lot easier to see what's going on when you get your multimeter.

     

    Here are the available RasPi schematics: https://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/README.md.  There are complete schematics for the original RasPi Model A/B (which use the same PC board) and a partial schematic for B+ which shows the 3.3V/1.8V switching regulator.  No published schematics for A+, RasPi 2, or Zero.

  • in reply to johnbeetem

    Both of it are B (Gen 1 B). For this one, I get the feel that the polyfuse has blown, so I'm leaving it off until I get my multimeter. What are the chances for a Gen 1 B to have its Power LED off but the rest are on?

  • in reply to wcypierre

    Slim to none.

     

    The power led is directly connected to IIRC, the 3.3V power line. If your PF is blown, the system cannot get any power (e.g. to power the act led), because it is the first component in the "power train". Similarly, IIRC, the other leds are ALSO powered from the 3.3V rails, so if there is no 3.3V, those leds cannot be lit either.

     

    This would imply that somehow your power led is blown. Weird situation! (I've never seen a led blow up completely unless you misuse it. They say 50000 hours of lifetime for a led, but in practice they dim a bit but still work fine).

  • in reply to rew

    Just to provide an update, after I've let it rest for a few days, I've tried to power it up again(since even the 100mbps network led is lit so I guess it may have a chance of getting it working). At first I was using a lower quality and longer cable and I wasn't able to ssh into it, but after I've replaced it with a shorter cable, it managed to boot!

     

    The PWR red led is still off though. Weird but I'm glad that it is back online. Will be monitoring it over the next few weeks.

  • in reply to wcypierre

    Thank you for updating us with your progress. image

  • in reply to wcypierre

    wcy pierre wrote:

     

    The PWR red led is still off though. Weird but I'm glad that it is back online. Will be monitoring it over the next few weeks.

    It could be that the PWR LED has died.  Unusual, but not unheard-of.  It's also possible that a PC board trace broke.  Since you have an original Model B you can get full schematics and check the voltage across the LED and its supposed-to-be-connected components.  With RasPi power off, you can check for PC board continuity with the Ohmmeter setting on your multimeter (when it arrives).