Raspberry Pi 3 A+ problem

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    Hello everyone.  I finished a project that has a Raspberry Pi 3 model A+ embedded in it.  When I first began looking for the best place and orientation for it in the project box, I decided I needed to cut a small piece off of the Pi - the bottom right-hand corner.  It appeared to me that the corner had no traces or purpose other than for the screw hole, so I removed it.  Well, that ended up preventing the Pi from booting.  It was booting correctly with the Raspberry Pi OS on its microSD card before I cut off that piece.  I couldn't figure out why it wasn't now, it didn't seem like I had damaged anything.  Thinking maybe that the "jolt" from the cut (from wire cutters) had caused the damage, I planned to do the same thing to a second Pi, but with more care.  With the second one, I chipped off a little bit, plugged it in to make sure the green LED lit, then chipped off a little more, plugged it to check it, and so on.  But when I got the notch to a certain size, that Pi bricked as well!  Obviously I'm consistently damaging a part of it.  I've attached a photo of both of them.  The only thing I can see is that my cuts are a bit close to that trace going to the RCA jack, so just to make sure, I soldered a jumper between the jack's connection and the small capacitor where the other end of the trace connects, but it didn't help.  Does anyone out there have any idea what the cause might be?  I'm hoping to fix it somehow (I can't buy a new one now).  And just a thought, but Raspberry Pies aren't multi-layered boards, are they?  Are there traces inside?

    I'm sorry that I'm asking for help with a problem that seems to have come about as a result of my own foolishness...  If I could do it over, I'd notch the project box instead...

    Thank you all for your help.

 

This topic has a solution.
Last Edited: Tue. May 31, 2022 - 07:19 PM
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The Rpi uses a multi layer board.  4 Layers or 6, I cannot remember, so your notch has probably(definitely) cut through some lines you needed for operation.

 

Might as well toss those in teh recycle bin and go buy some new ones....if you can find any.

 

JIm

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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DJJ_41010 wrote:
It appeared to me that the corner had no traces
A bright light behind the PCBA "may" show the interior traces and layers.

DJJ_41010 wrote:
(from wire cutters) 
Diagonal cutters exert great pressure; tin snips are slightly better for cutting FR-4 though best is to score then snap.

A guess is the inner power and ground planes shorted as there's typically a very thin insulating layer between.

DJJ_41010 wrote:
Raspberry Pies aren't multi-layered boards, are they?
Raspberry Pi indeed are multi-layer PCB; a rule is (N/2 - 1) PCB layers where N is the number of solder balls on one side of a BGA.

DJJ_41010 wrote:
If I could do it over, I'd notch the project box instead...
or instead a Raspberry Pi enclosure.

A Raspberry Pi Compute Module is more compact.

SAMA5D2 SoM fit on your PCBA.

 


ATSAMA5D27-SOM1 | Microchip Technology

Giant Board | Crowd Supply

Giant Board - Crowd Supply | Mouser

 

"Dare to be naïve." - Buckminster Fuller

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the corner had no traces or purpose other than for the screw hole, so I removed it.  

Oh why, oh why...get a bigger box.  or some sheet metal and bend a box up on the edge of your kitchen table.    At least they were old "scrap" rpi models (nowadays worth gold).

 

There is a slight chance you just crushed a power plane and gnd plane together* at the new edge, that is about the only thing that could possibly be fixed (by prying the touching planes apart.  You need to get a magnifier & probably a trashcan.

 

 

*that is why solid planes don't go all the way to the very edge (kept about 0.040-0.10 inch away), so they don't stick out beyond the "plastic" edge and short.  The cutting blade would bend them together.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Thu. Apr 14, 2022 - 12:05 AM
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A guess is the inner power and ground planes shorted

Do you have a jeweler's loupe, (eye piece), or a good microscope?

If so, you could get a good look at the cut edges and see if anything looks shorted.

If you, you might try correcting the problem with either an exacto knife blade, or perhaps a fine file.

 

Are you friends with any Vets or Dentists?

Perhaps one would take an X-ray of the corner of the PCB, (and hopefully a new / good board).

Then you / we could see the damage and make other / better recommendations.

If you go this route, you will need VERY GOOD, (NOT BLURRY!), photos of the Xrays, if they don't email them to you, (which they can likely easily do, they do this for consults and for some insurance payments).

 

Where in the world to you live?

 

Once X-rayed, attempting to repair an inner layer would be an interesting challenge.

 

JC

 

Edit:

Candies types faster than I do...

 

 

 

Last Edited: Thu. Apr 14, 2022 - 12:08 AM
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Candies types faster than I do...

And I noticed GChapman got ahead of me!!

 

If two planes are pressed, you might be able to "unzip" them, going down the joint with a sewing needle to spread open a gap.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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avrcandies wrote:
... or some sheet metal and bend a box ...
Ben uses sheet aluminum for structure to the engraving plastic sheet :

Creative Case Hacks: No 3D Printer Required! - YouTube (17m17s)

 


Web Portal for Benjamin J Heckendorn

Pololu - Custom Laser Cutting Service

 

"Dare to be naïve." - Buckminster Fuller

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So, who got the last piece of Pi's?

 

 

I'll get my jacket and leave now, thanks!

 

Jim

 

PS - I bet teh OP was quite Sur-Pi's-ed when they did not turn on! no

 

OK, OK officer!  I'm leaving!

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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    Oh, so it is multilayered...  I probably did irreversible damage to it.  But I am sure that it isn't shorting out, I'm not getting a power supply surge and the red light still comes on.

jgmdesign wrote:
if you can find any

    Yes, that's why I'm going to try and fix these...  I actually found out that someone started a Web site for the sole purpose of keeping track of Raspberry Pi availability.  I try to watch for sales on eBay too.

avrcandies wrote:
(nowadays worth gold)

    Yeah...

    I was actually a little worried that folks here would start frantically asking if they could buy the RPis cheap from me to try and get them working themselves...

DocJC wrote:
Where in the world do you live?

    I live in the US.  But I think that repairing an inner layer trace is beyond me.  I'm sure it would be an interesting challenge for some of you professional hackers... wink

gchapman wrote:
or instead a Raspberry Pi enclosure

    Thanks for that suggestion, but unfortunately I need space for additional components.  I think my project box is 5 by 3 inches or so.  I cut that notch because the enclosure had a screw hole mount sort of thing in a corner, and I needed the Pi's edges against the box's.  And thanks to all of you, I might try examining the inside layers closely.  I may just have to wait for the shortage to end and get a new one.  (Or find an eBay auction - the other day, there was a cheap one with damaged GPIO pins, but I don't even need GPIO, so now I sort of regret not bidding...)

    And yes Jim, I was very surprised.  I even flashed the Raspberry Pi OS to a new SD card, thinking I had damaged the first one.

Last Edited: Thu. Apr 14, 2022 - 02:35 AM
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Do you have to use that particular version of the Rpi?

 

jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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jgmdesign wrote:
Might as well toss those in teh recycle bin and go buy some new ones....if you can find any.

 

Maybe I am just a hoarder but I never throw things like this away. I strip them down using a heat gun and remove what I can recover to reuse later. I do that with all old and/or faulty electronics people don't want anymore. I recover a ton of transformers and connectors from such items just as an example. I don't use them where I want to build a nice shiny new project. I usually use them to fix specific things like .....

 

DJJ_41010 wrote:
there was a cheap one with damaged GPIO pins

Wayne

East London
South Africa

 

  • No, I am not an Electronics Engineer, just a 54 year old hobbyist/enthusiast
  • Yes, I am using Proteus to learn more about circuit design and electronics
  • No, I do not own a licensed copy of Proteus, I am evaluating it legitimately
  • No, I do not believe in software or intellectual property piracy or theft
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    It must be a Pi 3 due to my project's speed requirements and need for a full size HDMI.  I'd prefer a 3A+ since my project box is already fitted for it, but I could make a new one for a 3B or 3B+.  (I'd also prefer a 3B+ over a 3B for processing power.)

WayneZA wrote:
Maybe I am just a hoarder but I never throw things like this away. I strip them down using a heat gun and remove what I can recover to reuse later. I do that with all old and/or faulty electronics people don't want anymore.

    Yeah!  I salvage maybe half of my components from old PCBs (or from dead devices I receive from family members).

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Hello,  Most likely that the plating on the mounting hole was being used as a vertical connection VIA between the middle-layer and one of the surface layers.  For example, a ground-plane middle layer was using mount hole to go to a ground section on the top layer.  With a small microscope, like this ebay 60x $5 onehttps://www.ebay.com/itm/1332787... , check the fiberglass FR4 board where the clipping is.  See if there is a darker yellow/orange layer line that is not the same light yellow of the fiberglass. 

   This is the middle layer.   I use an inch of stripped AWG30 wire-wrap that is wrapped around the metal end of a DVM (digital Voltmeter) probe to touch the exposed copper of the middle layer.  Then I set the DVM to conductivity-beep and sweep all the pins on the top and bottom of the board.  If you find a connection, then you need to determine if it went to the top or the bottom layer.   It shouldn't be too difficult to find a  schematic for this Raspberry Pi A+.

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    You'll never believe this- I just started some various random tests, including poking around the notched spot with multi-core wire with the Pi plugged in, and it suddenly booted!  After shorting out the board a few times, the green light came on when the red one did!  I have no idea how it happened.  Now the green light comes on every time I plug it in, but something else is happening.  The Pi only outputs the HDMI video every once in a while.  Usually my monitor has no input when I first plug in the Pi, but if I poke around with the wire (and short it out) a little, it restarts and shows video.  I am thoroughly confused.  All I know is that its unreliable behavior isn't acceptable for my project.  So far, the second one still won't boot at all.

    Thank you Simonetta, I went ahead and added that magnifier to my recent eBay order.  I think I can see exposed copper on the edge of the cut, but I can't tell if my multi-core wire test was touching those specific spots.  I'll do some tests with my meter.

Simonetta wrote:
This is the middle layer.

    I'm sorry, I'm not sure I completely understand.  Are there only 3 layers with traces (top, middle, underside)?

    Thank you all.

 

 

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DJJ_41010 wrote:
    I'm sorry, I'm not sure I completely understand.  Are there only 3 layers with traces (top, middle, underside)?

I don't know that board, but as general rule, PCB's are usually 2 layer or 4 layer(power planes VCC/GND in the center) ie. even numbers of layers...

 

Jim

 

 

FF = PI > S.E.T

 

Last Edited: Fri. Apr 15, 2022 - 07:24 PM
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I just started some various random tests, including poking around the notched spot with multi-core wire with the Pi plugged in,

No, No, NO!

 

Don't do that it you wish to have any hope of repairing the PCB once you have a good magnifier to see the cut edges.

 

That is about like dropping a box of paper clips on your PC's mother board with the power turned on.

 

The goal is to see if you see any inner traces, and then attempt to determine where they connect, and to repair that connection.

 

Randomly poking about will likely cause MORE damage, likely unrepairable damage.

 

JC 

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    Oh okay I'll stop, thank you...  I didn't even think I might be messing it up even more but you're probably right.

    There was something else I was wondering about.  The Pi that I have set up as a PC is a Pi 3B (not +), and it's still running the old Raspbian system.  I was thinking about upgrading to Raspberry Pi OS 64 bit, but when I insert a properly prepared SD card, I don't get a display on HDMI.  (The green light does come on.)  The Raspberry Pi website says that the 64 bit OS is compatible with the old 3B and later Pies.  (What's the grammatically correct plural of "pi"?)

 

 

    Any thoughts?  Maybe I'll see if analog video works or not.  Thank you guys.

 

    Edit: Never mind about the HDMI thing, I messed around with config.txt and got it going.  Seems like my monitor wasn't detecting the signal and it needed boosting.

Last Edited: Sun. Apr 17, 2022 - 09:42 PM
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    Hey all, I'm bringing this post back up because I've made some more progress, but I'm starting to think it's hopeless.

    Using a magnifier, I saw several little traces inside the Pi, and it does seem like some have been crushed together.  When I previously got it to work intermittently (it won't at all now) by poking with a wire, I might have been momentarily separating them.  But how will I be able to separate them when I can't see them with my naked eye?  Any tool I have will probably be too large anyway.  I'd appreciate any input on what might help.  Toothbrush maybe?  I'm willing to try anything at this point.  Thank you all.

 

 

 

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jgmdesign wrote:
So, who got the last piece of Pi's?
Maybe RS; today's stock is now zero stock.

One may have to do a daily run through Octopart; distributor e-mail notifications may be enough though a lesson learned is don't delay reading your e-mail (should of forwarded to a smart phone or feature phone)

A distributor may have a web app API; might be low effort to create a very targeted search.

 

https://octopart.com/search?q=RASPBERRY+PI+3+A%2B&currency=USD&specs=0&in_stock_only=1

 

"Dare to be naïve." - Buckminster Fuller

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Toothbrush maybe?

Well, that will make it clean...

 

The photo brings to light just how small these traces are, and how small the distances involved are.

 

It also shows that you need about 10x more magnification to actually see the intra-trace linkage, and what you are trying to break.

 

You might try a fingernail emery board, (super fine file), to file the edge, or essentially "polish" the edge.  

The goal is to remove the small trace fragment that is extending beyond the cut edge and touching an adjacent layer.

 

JC

 

 

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We call your methodology as - chopping one's toe to avoid from sand worm.

 

laugh

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FWIW I'm 99% sure that the Pi 4 in front of me is a 6-layer board.

 

 

 

Throw yours away, you'll not be fixing it anytime soon. The mechanical stress that you've inflicted will run deep inside the PCB.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

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HKPhysicist wrote:

We call your methodology as - chopping one's toe to avoid from sand worm.

 

Everybody has to learn somehow.

Wayne

East London
South Africa

 

  • No, I am not an Electronics Engineer, just a 54 year old hobbyist/enthusiast
  • Yes, I am using Proteus to learn more about circuit design and electronics
  • No, I do not own a licensed copy of Proteus, I am evaluating it legitimately
  • No, I do not believe in software or intellectual property piracy or theft
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I don't think there is any way to fix it. Because Raspberry Pi is not open source. 

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I don't think there is any way to fix it.

 

Well, maybe, maybe not.

 

The schematics for it are available, and that is clearly one of the critical parts to "fixing" this.

 

The Gerber files are not on the RPi web site, so that is where the challenge comes in.

 

Clearly one can see the components in the neighborhood of the over-trimmed PCB.

Their connections would be the first ones to check, and correct.

 

If that failed to fix the board, then an X-Ray of the board would be very helpful, (as mentioned above).

 

including poking around the notched spot with multi-core wire with the Pi plugged in, and it suddenly booted! 

That is not an approved hardware debugging technique.

 

At this point it is hard to know that additional damage was don't, (lesson learned the hard way).

 

JC

 

 

 

 

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    Thank you guys for all your help and suggestions.  I did try an emery board on both, but no luck.  I'm starting to think that problem isn't two connected traces - after all, the Pies aren't shorting out, and they both have the exact same problem.  I probably cut a trace needed for operation, so...  I might just have to wait until I can find a new one.  I might keep working on it, but there's not much more I can do.  If I don't make any more progress I'll go ahead and close this thread.  Thanks again.

This reply has been marked as the solution. 
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    Since my last post, I was fortunate enough to obtain a new Pi at an online auction.  I'll keep working on the other two, but I'll mark this as the solution.  Thank you all for your suggestions and patience. 

Last Edited: Tue. May 31, 2022 - 07:28 PM