Problems with inaccurate assembled UmTRXv2

Alexander Chemeris alexander.chemeris at
Fri Nov 9 21:24:16 UTC 2012

Hi Andrey,

On Fri, Nov 9, 2012 at 9:55 PM, Andrey Sviyazov <andreysviyaz at> 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'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".

> 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?

> 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?

> 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.

Alexander Chemeris.
CEO, Fairwaves LLC / ООО УмРадио

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