stevenmclark1 2021/08/21 21:56


I just thought I would let y'all know that I had the spaghetti display problem above 140MHz and found a quick fix.

This is the same issue in the thread "can I repair this V2 plus 4?" and thanks to the info there I was able to demonstrate that this spaghetti display was only above 140MHz.
Thank you *barnc4br* and *OwO* for making it so easy to troubleshoot!!

I opened the unit up and found:
1) LED401 was not glowing solid blue the way it should
2) there were little bits of metal shorting the SMT pads of a chip under the metal shield
3) U401 looked like the solder hadn't really reached liquidus
4) when I looked at the other QFNs they had a similar morphology

The fixed was super simple... Apply a little bit of water soluble flux, touch up each joint, clean up and test.
When I heated the pads the solder sucked right under the chips in all cases, so I felt pretty confident that this would help.

Once I plugged it in... WOW!! This is GREAT!

Since this was a brand new unit, I suspect that the assembly house is rushing things and that they didn't take the time to "tune" the process.
Too bad, because I now have an additional 22 units I'm using for a class that I will need to test. :-(
If I have more with the same problem, I'll crank up the camera on my microscope and share some photos.

Thank you for letting me "bend your ear" and I hope it is helpful for anyone else finding that they have a spaghetti display.

- Steve
Northern CA, USA