Raspberry Pi Forums

Posted: **Thu Jun 18, 2020 6:13 pm**

Hello. Thanks for saving my Pi3 years and years ago of all it problems. Now I have a new one which I guess is unfixable. Sorry for my bad English, I'm from Spain but I'll try to do my best explaining my problems. Recently I was configuring retropie on my Pi when I needed to reboot. The Raspberry was working flawlessly fine. So, I pressed CTRL-ALT-DEL on my keyboard and the Pi died. Now when I plug any SD card the red light stays on. No ACT light. Sometimes the Pi manages to boot for some minutes and then, it dies again, repeating the same. I checked some voltages:

GPIO pin 1 and 2: ~5.1V and ~3V3 respectively.
PP1: 5V, same as input.
PP10: ~1.8V (is acting as a browndown detector?) I guess there's a problem here.
PP21: Should be high at 3V3 but I got ~0V
PP25: ~0V when it should be 5V on the USB bus.

Moreover, I supposed that some diode like D5 was fried and powered the Pi with regulated 5V via GPIO. It booted once into NOOBS and the died again with no more response but same voltages. It's annoying because I don't understand why sometimes boots and crashes or what could have happen with the little Pi. Is it time to get a new one or there's something I can do to bring it to life again? Thanks for all and I tried to search for all my issues here in the forum and Google and nothing helped me.

Posted: **Fri Jun 19, 2020 9:23 am**

javierilloqg wrote: ↑
Thu Jun 18, 2020 6:13 pm

GPIO pin 1 and 2: ~5.1V and ~3V3 respectively.

PP1: 5V, same as input.

PP10: ~1.8V (is acting as a browndown detector?) I guess there's a problem here.

PP21: Should be high at 3V3 but I got ~0V

PP25: ~0V when it should be 5V on the USB bus.

(I'm assuming this is a 3B, not 3B+ or other variant)

PP1 is on 5v input, GPIO header pin 1 is 5v after the ideal diode; both correct.
GPIO header pin 2 3v3 from the DC-DC, also correct.

PP10 is on the anode of the red LED; 1v8 means the LED is lit (it would read 5v if the LED wasn't lit)
PP25 is on the audio left channel of the trrs A/V jack. 0v is what it should be, since there's a capacitor before it and a resistor pulling it to gnd.

PP21 is on the RUN pin of the BCM2837. If it's at 0v the chip is halted.
It's fed with 3v2 from the potential divider R68 & R71 through R79.
Something is pulling it down, unless you have broken R68 or R79.

It might be worth connecting RUN to 3v3 with a resistor of between 1k and 10k, to see if that has any effect.

Posted: **Fri Jun 19, 2020 9:30 am**

Burngate wrote: ↑
Fri Jun 19, 2020 9:23 am
GPIO header pin 1 is 5v after the ideal diode; both correct.
GPIO header pin 2 3v3 from the DC-DC, also correct.

Shouldn't that be the other way round?

Pin 1 is 3v3 and Pin 2 & 4 are 5V.

Posted: **Fri Jun 19, 2020 10:22 am**

Hmph. Need more coffee

Posted: **Fri Jun 19, 2020 2:04 pm**

Burngate wrote: ↑
Fri Jun 19, 2020 9:23 am

javierilloqg wrote: ↑
Thu Jun 18, 2020 6:13 pm

GPIO pin 1 and 2: ~5.1V and ~3V3 respectively.

PP1: 5V, same as input.

PP10: ~1.8V (is acting as a browndown detector?) I guess there's a problem here.

PP21: Should be high at 3V3 but I got ~0V

PP25: ~0V when it should be 5V on the USB bus.

(I'm assuming this is a 3B, not 3B+ or other variant)

PP1 is on 5v input, GPIO header pin 1 is 5v after the ideal diode; both correct.
GPIO header pin 2 3v3 from the DC-DC, also correct.

PP10 is on the anode of the red LED; 1v8 means the LED is lit (it would read 5v if the LED wasn't lit)
PP25 is on the audio left channel of the trrs A/V jack. 0v is what it should be, since there's a capacitor before it and a resistor pulling it to gnd.

PP21 is on the RUN pin of the BCM2837. If it's at 0v the chip is halted.
It's fed with 3v2 from the potential divider R68 & R71 through R79.
Something is pulling it down, unless you have broken R68 or R79.

It might be worth connecting RUN to 3v3 with a resistor of between 1k and 10k, to see if that has any effect.

Hello again. Thanks for your reply. I tried what you suggested me with no luck. I think the SOC is fried. After connecting RUN with a 1K resistor to the GPIO pin 1 which is 3V3 and powering up, the Raspberry seemed to boot. The green light flashed a few times and then became static. After unplugging it from the official PSU and powering it again nothing happened. Red light and no ACT led. I don't know what's happening but I guess I should be buying the new one. Maybe this fault is unfixable. I misspelled the test point PP25 from the first post. I meant PP27, the test point for the USB ports, which gave me constant zero volts. Thanks for your help.

EDIT: I tried to boot without SD to see if it could be a problem with the SD card reader. No rainbow screen. Just a black one.

Posted: **Fri Jun 19, 2020 2:27 pm**

A blank screen is what you will get on a Pi3 that has no bootable SD card (unless it has been configured for USB or network boot and has either a bootable USB device or a suitable network boot server).
Until the first stages of the bootloader have been started the Pi has no concept of a screen (the Pi 4 is the first model to be able to display something without an SD card/network/USB device).

One sign of the SoC being dead is that it gets very hot - too hot to hold your finger on.

Posted: **Fri Jun 19, 2020 2:34 pm**

rpdom wrote: ↑
Fri Jun 19, 2020 2:27 pm
A blank screen is what you will get on a Pi3 that has no bootable SD card (unless it has been configured for USB or network boot and has either a bootable USB device or a suitable network boot server).
Until the first stages of the bootloader have been started the Pi has no concept of a screen (the Pi 4 is the first model to be able to display something without an SD card/network/USB device).

One sign of the SoC being dead is that it gets very hot - too hot to hold your finger on.

Hello. Oh, I see. I thought that on 3B when no SD card is inserted the rainbow screen appears too. My mistake. By the way, the SoC is at normal temperature. Now it is plugged with the same effects as before and it's cold. When it boots, it stays at normal temperatures. You can hold your finger on it. Thanks a lot.

Posted: **Tue Jun 23, 2020 5:44 pm**

javierilloqg wrote: ↑
Thu Jun 18, 2020 6:13 pm
Hello. Thanks for saving my Pi3 years and years ago of all it problems. Now I have a new one which I guess is unfixable. Sorry for my bad English, I'm from Spain but I'll try to do my best explaining my problems. Recently I was configuring retropie on my Pi when I needed to reboot. The Raspberry was working flawlessly fine. So, I pressed CTRL-ALT-DEL on my keyboard and the Pi died. Now when I plug any SD card the red light stays on. No ACT light. Sometimes the Pi manages to boot for some minutes and then, it dies again, repeating the same. I checked some voltages:

GPIO pin 1 and 2: ~5.1V and ~3V3 respectively.

PP1: 5V, same as input.

PP10: ~1.8V (is acting as a browndown detector?) I guess there's a problem here.

PP21: Should be high at 3V3 but I got ~0V

PP25: ~0V when it should be 5V on the USB bus.

Moreover, I supposed that some diode like D5 was fried and powered the Pi with regulated 5V via GPIO. It booted once into NOOBS and the died again with no more response but same voltages. It's annoying because I don't understand why sometimes boots and crashes or what could have happen with the little Pi. Is it time to get a new one or there's something I can do to bring it to life again? Thanks for all and I tried to search for all my issues here in the forum and Google and nothing helped me.

Hello again guys, after some trial and error, I manage to boot the Pi for a few seconds and I have this lines on the boot process:

I don't know what's wrong, but maybe it's something related to the general voltage and current of the Raspberry or even the SoC dying slowly. I have WiFi and Bluetooth errors too on Retropie.

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