Photon: SOS+1 / Extremly hot / short

Troubleshooting
1

Hi,
the story goes like that: I powered a 128x64 OLED Display by the Photon’s 3v3 pin, together with a I2C temperature sensor. Everything was powered with a (now presumably) faulty wall power supply that should have given the board 5V over the VIN pin.
The system worked for about 20 minutes, that’s when I noticed that the display doesn’t show anything new and the LED wasn’t breathing blue anymore, just a static blue at this time (like frozen). I immediately disconnected it from power and noticed that the whole board was extremly hot.

I repowered it with another power supply connected to the micro USB. The device starts with SOS+1, when I try starting it in safe mode it just restarts to SOS+1. However, DFU mode works.
I then conncted it to my laptop doing “particle update”/“particle flash --usb tinker” which tells me that both operations where “successful”, but the photon still restarts only in SOS+1. I then notice, that my device still gets extremy hot: Measured between 3V3 and GND there seems to be a short, but there is no short between VIN and GND (the pins I first used to power the device) and the both outer micro USB pads (what should be +5V and GND).

Is there anything I can do or did I fry it for good?

Thanks for your help
Marc

2

If you have a 3v3 supply, you can fit it directly to the Photon and see if it works.

1 Like
3

Let us know if Kenneth’s fix helps @shnytzl.

4

I don’t have a 3v3 power supply, I tried powering it with an Arduino through its 3v3, but that didn’t work, voltage breaks down to around 2v.

5

Sounds like the Photon is damaged.

You might want to remove all the circuitry and only power up the Photon just to be sure.

6

Removing everything else was the first thing I did. I ordered a replacement RT8008 DC-DC converter, how are my chances this will fix it?

7

The Uno supply can only provide 50ma which may explain why you are seeing a 2v level. You really need to test the Photon with a 300-500ma supply. If the STM32 is blown, a new RT8008 won't help.

8

If you haven’t got a reliable 3.3V source another Photon can give you enough current off the 3v3 pin for testing.

9

Thanks for that tip! Unfortunately the photon in question starts in SOS+1, so I guess it is dead... Should I try the new RT8008 or is that futile?

10

SOS+1 does indicate that at least some life is left in it :wink:
You could unsolder the supposedly frazzled regulator and try 3v3 power and DFU mode

particle update
particle flash --usb tinker

You could also try to reflash the bootloader - binaries should be available on GitHub.

11

Unsoldered and tried to update and flash the tinker script, both operations were “successful”, but the Photon itself keeps restarting in SOS+1. Didn’t try the bootloader binaries yet.