Was the culprit for the 625Mhz noise found? We have a similar issue and we suspect the USB.
On Wednesday, March 4, 2015 at 7:07:19 AM UTC-8, Gerald wrote: > > I suggest you add common mode chokes on HDMI, Ethernet, and USB. And on > any additional connectors you have coming from the board. > > Gerald > > > On Wed, Mar 4, 2015 at 8:41 AM, Jonathan Mash <[email protected] > <javascript:>> wrote: > >> Gerald, >> >> Thanks for the speedy response. We do have an enclosure for our product >> but it is made of PC so it doesn't help much with EMC. The test lab also >> tried "painting" it with this conductive paint but it didn't help enough. >> I'll take up your offer and take this offline and contact you directly. >> >> Thanks, >> >> Jon >> >> On Tuesday, 3 March 2015 19:05:56 UTC-5, Gerald wrote: >>> >>> A lot depends on SW as well. Best way to pass is to put it in a box, but >>> thee are some other things you can try that involve $$. >>> >>> You can contact me directly and we can have a lively discussion about >>> your issues. >>> >>> Gerald >>> >>> >>> On Tue, Mar 3, 2015 at 1:24 PM, Jonathan Mash <[email protected]> wrote: >>> >>>> Good Afternoon, >>>> >>>> First off, thanks to the BB community for making this such a great >>>> resource for those working on the BBB and other boards. I have personally >>>> spent hours on this forum. >>>> >>>> I am hoping that someone monitoring this group may be able to help me >>>> and my company solve an EMC problem that we are facing the the BBB. *We >>>> are open to paid consultations to aid in solving this issue (Gerald?)*. >>>> We are building a product around the BBB that needs to pass FCC part 15 >>>> Class B. We are having trouble passing the tests mostly around the 625 MHz >>>> range. We were only 1-2dB above the limit in one lab and almost 10dB over >>>> at another lab (yes, test equipment makes a big difference!). We tried it >>>> with and without our custom shield attached. >>>> >>>> There is another thread here: https://groups.google. >>>> com/forum/#!searchin/beagleboard/625/beagleboard/ >>>> Y6BhtzKx2oY/YQ_xjmmkWusJ that seems to have the same problem. That >>>> thread seems to have lost attention of the key players in this group so I >>>> thought I would create another thread to bring more attention to this >>>> critical issue. >>>> >>>> We have done some pretty aggressive modifications to the board and the >>>> only way we can get the board to pass is by completely disabling (and >>>> depowering) the LAN PHY. This was accomplished by removing FB4 and >>>> mangling >>>> part of the device tree so we don't get a kernel panic on startup. Not an >>>> elegant solution, I know. >>>> >>>> As suggested in the other similar thread, we tried shorting R136 but it >>>> actually made the noise worse. >>>> >>>> We also tried disabling (removing Y4) the McASP oscillator as that was >>>> also generating quite a bit of noise. Didn't help enough. >>>> >>>> Has anyone other than CircuitCo been able to successfully pass FCC with >>>> the BBBw/Ethernet enabled as part of a system? CircuitCo was probably able >>>> to pass because they could isolate the BBB with big filters on all cables >>>> because they aren't selling the BBB as as system but as a component. >>>> Because ours is a "Commercial System", we need to test with all cables as >>>> they would be typically installed. No giant chokes for us. >>>> >>>> Thoughts? Comments? Suggestions? >>>> >>>> Thanks! >>>> >>>> Jon >>>> >>>> >>>> -- >>>> For more options, visit http://beagleboard.org/discuss >>>> --- >>>> You received this message because you are subscribed to the Google >>>> Groups "BeagleBoard" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> >>> >>> -- >>> Gerald >>> >>> [email protected] >>> http://beagleboard.org/ >>> http://circuitco.com/support/ >>> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > Gerald > > [email protected] <javascript:> > http://beagleboard.org/ > http://circuitco.com/support/ > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/589b6a11-02a4-4042-bddc-6df1e632afde%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
