bytestorm
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Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 7:41 am

Hi!
I just got my first Raspberry Pi yesterday, and its the newest version.
Opening the box I noticed that the CPU is really off-centered, in the lower left corner of the silk screen.. should I worry about this?
I havent started it yet since I could not find my micro sd when I got home, but I will buy one today.

I dont know the tolerance of this type of chips placement (BGA/FBGA/MBGA?)

But since the pictures I have seen of this model online, all have the CPU perfectly centered, that leads me to belive that this was not supposed to loke like this.

Could this cause me trouble? Please see the attached photos. Thank you!

Image
https://dl.dropboxusercontent.com/u/878 ... Pi/Top.jpg
Image
https://dl.dropboxusercontent.com/u/878 ... i/Side.jpg

EtonMess
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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 7:50 am

Looking at the alignment of some of the other silk screen symbols on your board, I would say it is your silk screen that is slightly off, not the soldered on cpu chip.

The spacing between contact on the surface mount chips is quite small and if there was any problem then I think the board would have failed ATE and not made it out of Pencoed.
.G6FIR

ktb
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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 7:51 am

My 2B doesn't look like that, but my B+ does. It hasn't seemed to be a problem for me.

jamesh
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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 8:36 am

If it was misaligned, then it would not have passed testing at the factory. Every board is tested in a very impressive automatic test rig with conveyors, and all sorts of exciting stuff.

Not only that but I don't think that the pick and place machines they use actually make mistakes!
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bytestorm
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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 8:55 am

Wow, thanks all for the fast responses!
Good to hear that I dont need to worry! :D

Then I can relax :). Man am I exited to try this one out this afternoon!

Thanks once again!

ceteras
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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 12:04 pm

The pick and place machine aligns with the fiducial marks which are very precisely included in the actual pcb design.
You can see one of those in the first picture just above C97 in the upper right corner.

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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 1:38 pm

jamesh wrote:If it was misaligned, then it would not have passed testing at the factory. Every board is tested in a very impressive automatic test rig with conveyors, and all sorts of exciting stuff.

Not only that but I don't think that the pick and place machines they use actually make mistakes!
I'd love to see a video of a board going from blank to built. Last time I was at Pencoed they were still making Panasonic CRT TVs and I had a little mainframe that needed some brain surgery to get it running sensibly.

The last stage on the TV line was the girl with the rubber mallet who hit the TV three times before it got boxed for shipping.
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marked
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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 1:49 pm

DougieLawson wrote:The last stage on the TV line was the girl with the rubber mallet who hit the TV three times before it got boxed for shipping.
Pre-applied Percussive Prolongation?

Ravenous
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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 1:55 pm

marked wrote:
DougieLawson wrote:The last stage on the TV line was the girl with the rubber mallet who hit the TV three times before it got boxed for shipping.
Pre-applied Percussive Prolongation?
Pre-emptive prang prevention?

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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 2:14 pm

marked wrote:
DougieLawson wrote:The last stage on the TV line was the girl with the rubber mallet who hit the TV three times before it got boxed for shipping.
Pre-applied Percussive Prolongation?
It was a hangover from TVs with thermionic valves (before transistors). When you had a set which occasionally lost its picture you'd give it a slap. That had one of two effects: 1. it reseated the valves and it worked until next time, 2. it loosened them and made the failure permanent. You could then call the man from Curry's and he'd come out and fix it (hopefully with new valves). One of the dads of one of my mates in primary school was a TV repairman (he'll be about 80 by now). We don't repair TVs any more, we chuck them in the WEEE recycling and buy a fresh one.
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panik
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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 2:58 pm

Aah, the joy of slapping the TV at *just* the right place with *just* the right amount of force to get the picture back. Oddly satisfying.
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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 2:59 pm

DougieLawson wrote:
jamesh wrote:If it was misaligned, then it would not have passed testing at the factory. Every board is tested in a very impressive automatic test rig with conveyors, and all sorts of exciting stuff.

Not only that but I don't think that the pick and place machines they use actually make mistakes!
I'd love to see a video of a board going from blank to built. Last time I was at Pencoed they were still making Panasonic CRT TVs and I had a little mainframe that needed some brain surgery to get it running sensibly.

The last stage on the TV line was the girl with the rubber mallet who hit the TV three times before it got boxed for shipping.
There were some pictures taken whilst we were there, not sure what happened to them.
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Re: Raspberry Pi 2 Model B CPU not centered. Should I worry?

Fri Feb 06, 2015 3:25 pm

Those photos are for press - but I might whip some of them out for the blog on a quiet day.

Farnell made this video with Electronics Weekly in 2013. The factory has a kaizen approach, so the layout of the line and the machinery used is a bit different these days, but this is a good approximation of what it's like today.

https://www.youtube.com/watch?v=Tza6Hl8wSJ0
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