If you have a PI model A, A+ or Zero there is a special trick which can be used to check if such a PI is "dead":
Take your PI, with nothing in any slot or socket (yes, no SD-card is needed or wanted to do this test!). Take a (special) USB-A to USB-A cable (or a more normal micro-USB to USB-A for the zero) & connect it to your PC, plugging the other end of the cable into the Pi's USB port. If the PI is alive, your Windows PC will go ding for the presence of new hardware & you should see "BCM2708 Boot" in Device Manager. Or on linux, with a "ID 0a5c:2763 Broadcom Corp" message from dmesg. If you see that, so far so good, you know the PI is not dead.
You have a 3B+ so you cannot use that method.Tried the "Secret method" to check if my Pi was Dead... When plugged in, it did not "Ding" on windowsIf you have a PI model A, A+ or Zero there is a special trick which can be used to check if such a PI is "dead":
No prizes for guessing what I was guessing.
That won't work with a Pi 3B+ but if you have the skills and tools you can check to see if 3V3 is present on the GPIO power pins. If not, it seems it is another dead one.
No voltage from 3v3 Pin, 5V pin is showing constant 5v but nothing from 3v3. Guess its dead
I killed a 3B+ by accidentally shorting 3V3 pin 1 to the metal chip cover with RPi logo (GND). The RPi instantly went off.RaTTuS wrote: ↑Tue Aug 14, 2018 7:54 amyour warranty is still with the vendor
though adding a fan may have killed it in other ways
IMO it's possible the new power chip may have some issues in a batch - though warranty as before
any date marking on the board may be useful to the general issue
i'm not sure if you can supply 3.3v on that pin and make it work - I'm pretty certain that the SOC needs 1.8V and that may be also dead
The XR77004 marked on the circuit diagram seems to be an MxL7704 in reality - https://www.raspberrypi.org/blog/pi-power-supply-chipklricks wrote: ↑Tue Aug 14, 2018 12:49 pmI killed a 3B+ by accidentally shorting 3V3 pin 1 to the metal chip cover with RPi logo (GND). The RPi instantly went off.
The 3V3 reads 0V and also reads as as shorted to GND using Ohm meter. The PMIC is totally shut down so no 1V8 output either. Don't know if fault is internal or external to the PMIC?
How do you know that the damage is inside the SoC rather than in the MXL7704-R3? How many dead Pis have been inspected? If the MXL7704-R3 is replaced (expert soldering job for sure) does the Pi stay dead?The cause is well known and stated; shorting 3v3 to GND causes a latchup inside the SoC
I was thinking the SoC latchup was due to applying 4V or more to a GPIO pin. The usual symptom is the SoC quickly overheats and then eventual catastrophic failure. Not necessarily instant.
A quick google suggests: yes, it stays deadjbudd wrote: ↑Wed Aug 15, 2018 2:16 amHow do you know that the damage is inside the SoC rather than in the MXL7704-R3? How many dead Pis have been inspected? If the MXL7704-R3 is replaced (expert soldering job for sure) does the Pi stay dead?The cause is well known and stated; shorting 3v3 to GND causes a latchup inside the SoC
Some people report that their Pi died during reboot after an update.
Do you think it's possible that they gripped the device with a sweaty finger touching the RPi logo and GPIO1 to unplug the power lead? Or did they forget about poking around with a screwdriver?
It seems unlikely to me, because it is hard to see how damage in the SoC would causes the MxL7704 to not produce 3V3.
That seems to be an issue with using a greater than 5V supply. Applying higher voltages than the Pi is rated for can cause latch-ups in the SoC and cause failure but that is a different failure mode.
I think there is every likelihood a Pi would be restored to normal operation with the caveat that any replacement MxL7704 must be programmed before installation. There can be no definitive answer though until someone tries that, or removes the on-board MxL7704 and supplies the required voltages from an external source with correct sequencing.
One post here from a Pi 3B+ owner who reports shorting 3V3 to 5V, replacing the MxL7704, and getting their Pi working again ...
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