resurrected XO-1.5, died again

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resurrected XO-1.5, died again

Yioryos Asprobounitis
I do not know for how long the "toasted" [1] XO-1.5 boards worked but my "oven baked" [2] board died again after 8 months of daily use and a guestimated 400+ hours.
I do not know if this is long enough to justify the process (roughly half a school year worth, I would guess), but I thought to record it just the same.

The XO-1.5 is by far, my favorite of the 3 models I have (1, 1.5, 1.75). 
Does it make any sense (safety considerations aside) to retry it?
Any experience on that?
Thanks
Yioryos.

[1] http://lists.laptop.org/pipermail/devel/2011-August/032908.html

[2] http://lists.laptop.org/pipermail/devel/2012-October/036177.html

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Re: resurrected XO-1.5, died again

James Cameron-2
On Mon, Jul 01, 2013 at 12:53:47AM -0700, Yioryos Asprobounitis wrote:
> I do not know for how long the "toasted" [1] XO-1.5 boards worked
> but my "oven baked" [2] board died again after 8 months of daily use
> and a guestimated 400+ hours.  I do not know if this is long enough
> to justify the process (roughly half a school year worth, I would
> guess), but I thought to record it just the same.

Good data, thanks.

> The XO-1.5 is by far, my favorite of the 3 models I have (1, 1.5,
> 1.75).   Does it make any sense (safety considerations aside) to
> retry it?

It makes as much sense as it always did, I think.  Given that you
can't change the composition and position of the metals, the problem
might still come back.

You now have a chance to review your safety considerations too.  I
would not use the same oven for food ever again, for instance.

--
James Cameron
http://quozl.linux.org.au/
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Re: resurrected XO-1.5, died again

Yioryos Asprobounitis
----- Original Message -----

> From: James Cameron <[hidden email]>
> To: Yioryos Asprobounitis <[hidden email]>
> Cc: OLPC Devel <[hidden email]>
> Sent: Monday, July 1, 2013 11:02 AM
> Subject: Re: resurrected XO-1.5, died again
>
> On Mon, Jul 01, 2013 at 12:53:47AM -0700, Yioryos Asprobounitis wrote:
>>  I do not know for how long the "toasted" [1] XO-1.5 boards worked
>>  but my "oven baked" [2] board died again after 8 months of daily
> use
>>  and a guestimated 400+ hours.  I do not know if this is long enough
>>  to justify the process (roughly half a school year worth, I would
>>  guess), but I thought to record it just the same.
>
> Good data, thanks.
>
>>  The XO-1.5 is by far, my favorite of the 3 models I have (1, 1.5,
>>  1.75).   Does it make any sense (safety considerations aside) to
>>  retry it?
>
> It makes as much sense as it always did, I think.  Given that you
> can't change the composition and position of the metals, the problem
> might still come back.

I guess what I'm asking is that the original board was good for more than 2 years. After the reflow, lasted 8 months.
Is a second reflow likely to last 8 months or 8 days (if at all)?
Thx
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Re: resurrected XO-1.5, died again

James Cameron-2
On Mon, Jul 01, 2013 at 02:19:07AM -0700, Yioryos Asprobounitis wrote:
> I guess what I'm asking is that the original board was good for more
> than 2 years. After the reflow, lasted 8 months.
> Is a second reflow likely to last 8 months or 8 days (if at all)?

Yes.  ;-)

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Re: resurrected XO-1.5, died again

Yioryos Asprobounitis




----- Original Message -----

> From: James Cameron <[hidden email]>
> To: Yioryos Asprobounitis <[hidden email]>
> Cc: OLPC Devel <[hidden email]>
> Sent: Monday, July 1, 2013 1:42 PM
> Subject: Re: resurrected XO-1.5, died again
>
> On Mon, Jul 01, 2013 at 02:19:07AM -0700, Yioryos Asprobounitis wrote:
>>  I guess what I'm asking is that the original board was good for more
>>  than 2 years. After the reflow, lasted 8 months.
>>  Is a second reflow likely to last 8 months or 8 days (if at all)?
>
> Yes.  ;-)
>
Oh, good. That clears it then.
Thanks for the insight :-P
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Re: resurrected XO-1.5, died again

Martin Langhoff
On Mon, Jul 1, 2013 at 6:51 AM, Yioryos Asprobounitis
<[hidden email]> wrote:
>> Yes.  ;-)
>>
> Oh, good. That clears it then.
> Thanks for the insight :-P

Perhaps repeated torsion on the board is one of the factors at play.
You may get a longer life out of it by ensuring that the unit is
tightly assembled (specially the screen, which gives the unit a lot of
its rigidity).

If you use the unit with the screen attached with only a couple of
screws, or those screws are not firmly screwed, the mobo is likely to
be getting more than its fair share of torsion. All the main frame
deserves a good tight assembly.

One question that I have in my mind is: assuming Yioryos' unit has
only glue in the corners of the CPU, does it make sense to add some
glue with a melting glue stick around the perimeter of the CPU casing?
[ I suspect the answer is no; the cheap melting glue sticks are
entirely unlike the glue used around the perimeter of the CPU... ]

cheers,



m
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Re: resurrected XO-1.5, died again

James Cameron-2
On Mon, Jul 01, 2013 at 11:16:29AM -0400, Martin Langhoff wrote:

> On Mon, Jul 1, 2013 at 6:51 AM, Yioryos Asprobounitis
> <[hidden email]> wrote:
> >> Yes.  ;-)
> >>
> > Oh, good. That clears it then.
> > Thanks for the insight :-P
>
> Perhaps repeated torsion on the board is one of the factors at play.
> You may get a longer life out of it by ensuring that the unit is
> tightly assembled (specially the screen, which gives the unit a lot of
> its rigidity).

I agree.  I'd go further ... don't open and close the lid, don't throw
it around, and don't give it to a child.  (We're talking about a known
defect here that affects a very small number of laptops,
http://dev.laptop.org/ticket/10314 )  Give it a nice easy life
sitting on a desk.  Retire to pasture before heading to the knackery.

> If you use the unit with the screen attached with only a couple of
> screws, or those screws are not firmly screwed, the mobo is likely
> to be getting more than its fair share of torsion. All the main
> frame deserves a good tight assembly.

I agree.  I've found laptops with looser-than-i-would-like hinge and
motherboard screws after children have been using them.  The hinge
screws that are uncovered by disassembly were the most interesting.

> One question that I have in my mind is: assuming Yioryos' unit has
> only glue in the corners of the CPU, does it make sense to add some
> glue with a melting glue stick around the perimeter of the CPU
> casing?  [ I suspect the answer is no; the cheap melting glue sticks
> are entirely unlike the glue used around the perimeter of the
> CPU... ]

No idea ... but a good way to prove the method is to do it to 100
units and then study the results after accelerated life testing on a
shaker platform.  ;-)

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James Cameron
http://quozl.linux.org.au/
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Re: resurrected XO-1.5, died again

John Watlington

On Jul 1, 2013, at 6:24 PM, James Cameron wrote:

> I agree.  I've found laptops with looser-than-i-would-like hinge and
> motherboard screws after children have been using them.  The hinge
> screws that are uncovered by disassembly were the most interesting.

There was a problem with the manufacturing process which
resulted in some of the externally accessible hinge screws
being cross-threaded or not fully tightened on the assembly line.
This process has been changed, but will require future monitoring.

wad
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Re: resurrected XO-1.5, died again

Yioryos Asprobounitis
>>  I agree.  I've found laptops with looser-than-i-would-like hinge and

>>  motherboard screws after children have been using them.  The hinge
>>  screws that are uncovered by disassembly were the most interesting.
>
> There was a problem with the manufacturing process which
> resulted in some of the externally accessible hinge screws
> being cross-threaded or not fully tightened on the assembly line.
> This process has been changed, but will require future monitoring.
>
> wad
>

Just to clear that my XO-1.5 had nothing loose or missing after reassembly and although I did not use a torsion screwdriver everything was fastened and still is.
Also I did not have it open on my desk but avoided throwing it around too. 

Back to the original question. Should I conclude at this point that there is no information/experience  on the effect of repetition on the effectiveness of the soldering reflow process? (ie try and see what happens ;)
Thx
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Re: resurrected XO-1.5, died again

James Cameron-2
On Tue, Jul 02, 2013 at 12:58:17AM -0700, Yioryos Asprobounitis wrote:
> Back to the original question. Should I conclude at this point that
> there is no information/experience  on the effect of repetition on
> the effectiveness of the soldering reflow process? (ie try and see
> what happens ;)

Beyond comments in #10314 and on various mailing lists (devel@ and
support-gang@), we've not attempted to concentrate this information or
experience.  Have fun!

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Re: resurrected XO-1.5, died again

Ian MacArthur
In reply to this post by Yioryos Asprobounitis
On 2 Jul 2013, at 08:58, Yioryos Asprobounitis wrote:

> Back to the original question. Should I conclude at this point that there is no information/experience  on the effect of repetition on the effectiveness of the soldering reflow process? (ie try and see what happens ;)

No OLPC information. However, a little time with google looking for the PS3 "yellow light of death" of the Xbox-360 "red ring of death" will produce more opinions than could ever be wanted, all based on no substantial evidence whatsoever...




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Re: resurrected XO-1.5, died again

John Watlington

I'm tired of revisiting an issue that thankfully only affected less
than a thousand production units (repaired under a catastrophic
failure clause).  Unfortunately, the effect on our developer
community was disastrous, as they only received affected units.

I'm willing to send an XO-4 to replace a broken XO-1.5
if you tell me what you are using it for.

The root cause was the alloy used in the solder balls between the
CPU interposer board and the CPU silicon.   These balls are under
significant stress due to the difference in coefficient of thermal expansion
between FR4 and silicon.   This problem only showed up after the
solder balls had had time for the alloy to separate.
VIA switched the RoHS alloy used in these balls as we were entering
production.

So while mechanical stress on the motherboard might accelerate the
problem, simple thermal stress from powering the device on (or moving
in/out of suspend) is a more likely culprit.

wad


On Jul 2, 2013, at 3:26 PM, Ian MacArthur wrote:

> On 2 Jul 2013, at 08:58, Yioryos Asprobounitis wrote:
>
>> Back to the original question. Should I conclude at this point that there is no information/experience  on the effect of repetition on the effectiveness of the soldering reflow process? (ie try and see what happens ;)
>
> No OLPC information. However, a little time with google looking for the PS3 "yellow light of death" of the Xbox-360 "red ring of death" will produce more opinions than could ever be wanted, all based on no substantial evidence whatsoever...
>
>
>
>
> _______________________________________________
> Devel mailing list
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> http://lists.laptop.org/listinfo/devel

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