vargabp
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Pi 3 B+ Red light [mystery solved]

Sat Sep 08, 2018 9:43 am

Solved: Make sure the case is specifically made for your model.
To check, screw the case shut without the Pi inside. If it closes nicely, try again with the board inside (safe to say you wouldn't want to plug it in at this point). It it doesn't close properly, it means the board is in the way, and the case is not meant to go with your Pi. Don't touch the screws, send the case back, get another one. Don't try to adjust the case, or the board to fit. Who knows what you'll end up damaging. In my case it was most likely the CPU (it's got a higher profile than model 3).
Also PoE pins could be touching the metal case (it wasn't my case...:) ), or other pins, plenty of things to go wrong.
--------------------------------------------------------------------------------------------
Hi,

I went through the sticky on boot issues, and couldn't fix the problem.

I bought a 3B+ a few days ago and wrote an image of RetroPi onto a 32 GB card. I connected a wireless keyboard dongle (logitech unifying receiver), a power supply (OnePlus 6 Charger rated at 5V, 4A), and a HDMI cable to a Samsung TV).

Worth mentioning is that the unit was enclosed inside a metal case with bits touching the lan, ram, and cpu chips, and no other electrical components. Thermal compound was used in a conservative manner, all very neatly applied, no spills.

It powered up and ran, went through some updates, powered it down (via software, not uplugging), then it froze while shutting down. I went CTRL ALT DEL on it (windows guy). It powered off, and nothing ever since.

Currently the red led stays on, and no green light whatsoever. No flash, no blink, not even briefly turning on.

What I've tried:

*Note when I say "format" I mean using the "clean" command in CMD fdisk diskpart, then formating the card with overwrite with the official SD Card Formatter.

1. Assumed it was the corrupt data on the SD card. I've burnt the same image all over again to bring it back to the previous working state. Did not work. Tried the most recent version of Noobs (files inside the root of the formated FAT32 partition), burnt image of newest Raspbian (on card, not a partition on the card)after formatting, burnt pwnpi, then Noobs lite (again files in root), then Raspbian lite image burn onto the card (not the partition).
None of them workied.
2. Bought a couple more SD cards, thinking something went wrong on the hardware side of the SD card preventing it from being used as a booting deivce (grasping at straws). Repeated step 1 with both of them, no cookie.
3. Tested voltage with the multimetre, It gets 5.21V before the polyfuse, 5.19V after it. Tested the power adapter white unplugged from the Pi, supplying 5.21V slight variation towards 5.22V.
4. Removed the polyfuse, replaced with 0ohm rez. Red light on just like before, only now I get 5.20V after the 0ohm. Tried booting, didn't work. Soldered the polyfuse back.
5. Disconnected micro usb power, then fed 5.2V straight into the GPIO pin +2 , grounding it with pin -6. Red light on, no boot.
6. Checked the contact of the microSD card onto the board. Desoldered the metal top of the SD slot, to reveal all the pins were in good condition, gave them a slight upwards bend with a needle just in case. The presence spring made proper contact with the other metal bit, so the card could be detected. Closed back up, red light, no boot.
7. Tried powering on with only SD card and LAN cable connected, to potentially SSH into it, in case the error was caused by the hdmi cable or keyboard dongle being connected, nothing. Red light on the Pi, no green light on it, none on the RJ45 slot.
8. Went to sleep crying, woke up, red light, no boot.
9. Left it alone another day, plugged in, red light, no boot.

It think this covers pretty much everything.

Any other ideas?
Last edited by vargabp on Mon Sep 10, 2018 9:31 pm, edited 2 times in total.

klricks
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Re: Pi 3 B+ Red light

Sat Sep 08, 2018 2:43 pm

Carefully measure the 3V3 between pin 1 and ground (any port shield). Do not slip and accidentally short 3V3 to ground else you RPi will be instantly destroyed BTDT.

If 3V3 is not there then time to buy a new RPi.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

vargabp
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Re: Pi 3 B+ Red light

Sat Sep 08, 2018 3:09 pm

klricks wrote:
Sat Sep 08, 2018 2:43 pm
Carefully measure the 3V3 between pin 1 and ground (any port shield). Do not slip and accidentally short 3V3 to ground else you RPi will be instantly destroyed BTDT.

If 3V3 is not there then time to buy a new RPi.
Thanks for your reply.

I measured 3.3V while probing positive 1, negative on the SD cover, also 3.3V on +17, negative on SD cover plate.
*edit: numbered by actually counting the pins, top row closest to the edge of the Pi 2, 4, 6, 8 ..... 40, bottom 1, 3, 5 --- 39.

I've also received another slice of Pi just hours ago which works with the same SD card, PSU and HDMI destination.
I'll be able to test against each other, but I've no idea what to look for.

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mahjongg
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Re: Pi 3 B+ Red light

Sat Sep 08, 2018 3:12 pm

Try to peer into the sd-card socket to see if you see any bent pins in it preventing contact to the sd-card.

p.s. I see you already covered that, note that a PI does not use any card detect or write protect switches.

you could try check if the PI's 1V8 supply is working, use the partial schematic you can find in the help section of the blog.
note that there isn't much to a PI you can repair yourself. if you have an oscilloscope you can check if the crystal is running, but for most part a PI will only "wake up" when it has read bootcode. you could check for the sd-card clock signal.

but principally is seems you can say "its dead jim".
seems time to make use of your guarantee and exchange your PI for a new one, don't tell them you tried to repair it yourself, as that will void your warrantee (assuming they care about that).

vargabp
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Re: Pi 3 B+ Red light

Sat Sep 08, 2018 7:04 pm

I'm assuming that the crystals would be the bits market XTAL on the schematic.
Unfortunately I don't have an oscilloscope, and if I had one, I' wouldn't be experienced enough to understand what the lines meant.
At the moment I'm just randomly probing components on both boards, trying to find something different.

Only difference was the old polyfuse which says 1.1 ohm, new one says 0.1 ohm. Could be due to intense soldering heat. But I wouldn't attribute the fail to the polyfuse, since replacing it with a 0 ohm resistor did nothing. I'll leave it alone for a while and get back to it after more ideas pop up.

I don't have much hope left. I'll have to settle for the one I've got for the time being.
Hiding the fact that I've worked on it is not a possibility, because of the obvious soldering work.
I'll study the warranty terms and conditions to see if I can return it after working on it.

Any other ideas (even crazy long shots)would be much appreciated. It's broken, it can't get double broken.

Thanks for the input!

LTolledo
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Re: Pi 3 B+ Red light

Sat Sep 08, 2018 9:32 pm

Tried booting from USB flash drive?

could be the microSD part is malfunctioning...

if booting from USB flashdrive doesnt work either better heed mahjongg's suggestion to initiate RMA for your RPi3B+
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Come to me with 'problems' and I'll help you find solutions"

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vargabp
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Re: Pi 3 B+ Red light

Sun Sep 09, 2018 7:19 am

Is there any way to enable boot from USB without having to actually boot with a card?
I thought you had to change a bit inside the one-time programmable memory.

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B.Goode
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Re: Pi 3 B+ Red light

Sun Sep 09, 2018 7:40 am

vargabp wrote:
Sun Sep 09, 2018 7:19 am
Is there any way to enable boot from USB without having to actually boot with a card?
I thought you had to change a bit inside the one-time programmable memory.

You don't have to set that bit on an RPi 3b+. It is now preset on the production line.

Just 'flash' the Raspbian image to a usb mass storage device, connect it to the RPi and apply power.

vargabp
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Re: Pi 3 B+ Red light

Mon Sep 10, 2018 9:05 am

Did that and it didn't work...
I've also tested the USB flash drive on a new working unit and it booted up nicely.
There was something new this time around. Heat.
There was no green light, but the board started worming (no worms involved) warming up slightly while powering it up with the USB flash drive and LAN cable plugged in. I would estimate somewhere around 35-40 degrees Celsius on the CPU and LAN chip. And, no, no light on the RJ45 connector either.

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HawaiianPi
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Re: Pi 3 B+ Red light

Mon Sep 10, 2018 9:53 am

vargabp wrote:
Sat Sep 08, 2018 9:43 am
... Worth mentioning is that the unit was enclosed inside a metal case with bits touching the lan, ram, and cpu chips,
Are you absolutely certain the case was designed for the newer 3B+ model and not the older Pi 3B?

If it was a Pi3B case it could have shorted something out (different chip locations, and an extra POE header on the 3B+), or put too much pressure on the SoC (System-on-Chip is taller on the 3B+).
My mind is like a browser. 27 tabs are open, 9 aren't responding,
lots of pop-ups...and where is that annoying music coming from?

vargabp
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Re: Pi 3 B+ Red light

Mon Sep 10, 2018 10:10 am

HawaiianPi wrote:
Mon Sep 10, 2018 9:53 am
vargabp wrote:
Sat Sep 08, 2018 9:43 am
... Worth mentioning is that the unit was enclosed inside a metal case with bits touching the lan, ram, and cpu chips,
Are you absolutely certain the case was designed for the newer 3B+ model and not the older Pi 3B?

If it was a Pi3B case it could have shorted something out (different chip locations, and an extra POE header on the 3B+), or put too much pressure on the SoC (System-on-Chip is taller on the 3B+).
You might be right.

The title of the listing on Amazon is:
KKmoon Aluminum Alloy Protective Case Housing Shell Enclosure Box for Raspberry Pi 3, Pi 2 and B+

The B+ at the end made me think it would be compatible with the 3b+. The case did require some force applied while turning the screws now that I think of it. Closing the case without the board inside requires no excessive force, now that I try it.

I guess the mistery is solved. User error.
I don't suppose the SoC is something I could swap out with hot air...?
Anyway. I've got a very expensive red LED now.

Thank you guys for your help!

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Re: Pi 3 B+ Red light

Mon Sep 10, 2018 1:09 pm

B.Goode wrote:
Sun Sep 09, 2018 7:40 am
vargabp wrote:
Sun Sep 09, 2018 7:19 am
Is there any way to enable boot from USB without having to actually boot with a card?
I thought you had to change a bit inside the one-time programmable memory.

You don't have to set that bit on an RPi 3b+. It is now preset on the production line.

Just 'flash' the Raspbian image to a usb mass storage device, connect it to the RPi and apply power.
This is correct, the 3b+ has that bit set automatically.
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drgeoff
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Re: Pi 3 B+ Red light

Mon Sep 10, 2018 1:38 pm

vargabp wrote:
Mon Sep 10, 2018 10:10 am
I don't suppose the SoC is something I could swap out with hot air...?
Even if you could source a replacement SoC (which to all intents and purposes you cannot) the probability of successfully swapping one out with hot air is low.

vargabp
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Re: Pi 3 B+ Red light [mystery solved]

Mon Sep 10, 2018 7:31 pm

Ok then. I'll just shelf it and use it for spares for my new one should something happen.
Thank you all for the input!

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