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LG's UltraFine 5K Display Becomes Useless When It's Within Two Meters of a Router (9to5mac.com)
The LG UltraFine 5K Display was designed in part by Apple to work with the New MacBook Pro and as a replacement for the Thunderbolt Display, which was discontinued late last year. According to 9to5Mac, the display apparently wasn't designed to work next to routers as it will flicker, disconnect, or freeze computers when it's within two meters of a router due to electromagnetic interference. The Verge reports: In emails to 9to5Mac, LG acknowledged the problem -- which LG says isn't an issue for any of its other monitors -- noting that routers "may affect the performance of the monitor" and that users should "have the router placed at least two meters away from the monitor" to avoid issues. Once the monitor was moved into a different room away from the router, 9to5Mac says the issues subsided. Despite the fact that it's insane to require a router to be far away from what is likely the main computer in your home, there's been no indication that LG is working on a fix for the issue, which may be more troublesome.
Perhaps they don't have proper shielding? or is this a USB-C cable related problem?
Somebody should experiment by covering it up in various ways and see where the problem is. Start with the cable... since USB-C seems to have not been well thought out.
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Given the amount of money and time poured into these products, you'd think they'd have done proper EMI susceptibility at some point. It's moderately expensive, but easy enough for LG to afford.
If I owned one of these, I'd have to be pushing for them to take it back - there's bound to be other devices that trigger the problem than routers.
A thousand pounds of wood moving at 300 feet per minute. Don't get in the way.
I get to deal with weird stuff like this at work all the time. Based on the behavior, I'd guess there's a clock and/or data running at a harmonic of the wifi data. Freezing seems to indicate it's coupling into the core of the LCD controller board, which again I would guess is a timing violation or data corruption. Where it's coupling in is a bit hard to determine without further testing. It could be the video cable, could be the power cable (not likely), could be the LCD panel itself acting as an antenna, or an interconnect cable that is poorly shielded or just the right length to couple in wifi. It could also be power supply ripple caused by a feedback loop getting energy coupled in, though if that's possible then there's not enough timing margin to begin with.
I suggest a number of tests to narrow down details of the source:
- Test 2.4GHz and 5GHz independently. Test each wifi channel independently.
- Try a different length cable. Try a different brand cable. Does this monitor remain on with nothing connected? If so then try it with no cable, or no PC at the end.
- Try different antenna angles. Try different TX power levels (at what level does it start).
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Based on those results I'd have more recommendations.
If someone wants the real root cause, feel free to send me one and I'll debug it (though it will probably require disassembly).
As someone who has produced a few products sold around the world I can't see how this monitor reached the retail selves. To sell you generally need to pass immunity and emissions compliance test to FCC or CE standards depending on the market. Emissions means you don't transmit signals above a specified levels and immunity requires your products are not affected below a specified level. The levels vary with frequency and standards but generally the immunity threshold is several magnitudes higher than the emissions thresholds for non-transmitting devices. The WiFi device is an intentional radiator so is allowed higher emissions levels, at it operating band, but immunity levels for the monitor should be able to handle it easily.
It sounds like a clear failure of the LG monitor and if the nature of the failure reported is correct it sounds like it is not up to standard for immunity. Assuming the problem reported is in the USA then it will be the FCC standards that apply. If I was an owner of an affected LG monitor I would be demanding a copy of the immunity compliance test report. The test report will document what power level was used for the WiFi frequencies and these can be compared with the legal limit for WiFi devices.
Bottom line is this should never happen on modern products. I know my teams have spent many hours modifying product designs to ensure compliance before we release to market. If LG have not done this then they need to step up and fix the problem at their expense, before the FCC demand a product recall.