Problems with inaccurate assembled UmTRXv2

Andrey Sviyazov andreysviyaz at gmail.com
Sat Nov 10 15:16:00 UTC 2012


Hi Alexander.

2012/11/10 Alexander Chemeris <alexander.chemeris at gmail.com>

> Hi Andrey,
>
> On Fri, Nov 9, 2012 at 9:55 PM, Andrey Sviyazov <andreysviyaz at gmail.com>
> wrote:
> > I got two UmTRXv2 and both with the problems of inaccurate assembling.
>
> I wonder, do they do at least visual inspection of boards after
> assembly? This again reminds us that we have to create a test
> procedure for the fab before we start manufacturing in quantities. If
> you're a community member who could contribute to the test procedure -
> we would greatly appreciate that (mention on the web-site, t-shirt,
> even free hardware).


I am afraid that I didn't understood what do you mean.


> I'm willing to try a simple semi-automated visual testing - make
> pictures of all boards and then subtract them from a reference one. If
> performed well, we should clearly see all errors on the resulting
> picture. The only question is how hard is it to "perform well".
>

Do you mean to design some tooling and firmware/software for testing?


>
> > 1st Thomas sent to me and 2nd was new and clear (say, virgin).
> >
> > Thomas said about power supply symptoms few days ago.
> > I fixed assembling error in DC/DC - power coil (L37) was 90 degrees
> rotated.
> > It was too big surprise for me, because I replaced all components around
> > coil before I saw that it soldered incorrect.
> > Anyhow,This board began to work, but LMS2 still didn't hears SPI and
> didn't
> > work.
>
> Do you think it's a result of bad soldering and rework might help?
>

I'll try to fix LMS2. It is doable for me because required just warm up
board and to push LMS2 a little bit.


>
> > Also I found that mashine lost one 0.1uF cap (C86-1) near LMS1, but it
> was
> > easily to fix.
> > LMS1 and all other parts, seems working fine.
> >
> > Second board programmed and working, but FPGA too hot and 3.3V loaded a
> lot.
>
> You think the FPGA itself is broken?
>

If everything work, then extra current goes inside FPGA chip.
So, yes, I'm sure, almost.


>
> > Seems, I have to find BGA reworking station to fix both boards finally.
> > Also needed new Spartan-6 FPGA for replace.
> > Alexander, do we have spare on hands?
>
> Nothing on hands. We should check with Andrew Karpenkov and his
> connections at InlineGroup - they should have a stock of those chips
> and a BGA reworking station. E.g. they repaired our blown SP-605.


It would be fine, if InlineGroup can repair this board.
I know that without FPGA repair station I can easy to damage PCB and I want
to do it.
At least we need to order FPGA with lead solder balls to make repair at
lower tem.

Best regards,
Andrey Sviyazov.
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