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78648
July 25th, 2015 12:00
U2415, Blinking, going black, USB not working after power cycle
I have a new U2415, s/n CN-OPVJVW-74261-53B-1LOL, ver A02, mfg March 2015, attached by included DisplayPort cable to a Dell XPS 15 (L501X). Included USB cable is also attached to the XPS 15. Running Windows 7 Ultimate with all updates applied. Monitor is running at native resolution (1920x1200). After a couple hours use, the monitor begins blinking -- screen goes completely black and then returns after less than a second (or longer). Sometimes screen just goes completely black. Power light is still on. Turning monitor power off and back on usually resolves this problem for a few more hours, although the time to failure is variable. After cycling power, USB ports are frequently no longer functional and I have to reboot the computer to regain working USB ports. Connected to USB are an Alfa USB-wifi adapter (for improved wi-fie reception) and a Rosewill mechanical keyboard. I have run this same computer using DisplayPort successfully, for more than a year, with a U2711 monitor, so I'm relatively confident the problem is in the U2415 and not the computer. I plan to return the monitor under the 21-day return policy unless someone has a suggestion about what I could do to fix this problem.
DELL-Chris M
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July 25th, 2015 20:00
First, due to interference, I would never plug a USB WiFi into the monitor. I would plug that directly into the computer. If you must, plug it into the monitor back USB port, not the bottom. See page 9 in the manual which specifically references wireless device and port 6. The keyboard should be plugged into port 9b, see manual page 10.
Second, is the laptop entering some kind of hibernate when the blinking appears? Or are you actively using the laptop?
Third, have you checked the laptop power management options and made sure that USB and PCIe are set to never turn off?
GuyScharf
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July 25th, 2015 22:00
Thank you. I've moved the WiFi adapter to a port on the computer and the keyboard from 9a to 9b. (The keyboard is wired, not wireless, and I don't see that the manual says that a wired keyboard needs to be on 9b.) We'll see if those changes help. It may take a day or two to see if this intermittent failure is gone.
No, the laptop is not hibernating in any way; I am actively using the laptop when the monitor starts blinking.
Laptop is plugged in when the problem occurs and power settings are all set not to turn things off. The blinking behavior did not occur when the same laptop was attached to a U2711, and I would have expected to have seen the same behaviors there if the problem was in the laptop.
(I am disappointed that use of the USB ports is so restricted. The marketing literature gives no clue that there are any restrictions on how the USB ports can be used.)
DELL-Chris M
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July 27th, 2015 09:00
Agreed. But the marketing is limited in space, while the Manual is not.
GuyScharf
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July 29th, 2015 19:00
The USB connection changes did not solve the problem. Just now, I was working on the computer looking at some web sites and the screen started blinking on and off again. Cycling power to the display resolved the problem.
But I don't consider having to cycle power at unexpected times to be an acceptable solution; the display should not act this way.
I did submit a return request on 7/25. I got an email back after submitting the request saying that I would receive an additional email with waybill and return instructions. But I have not received anything. How long should I have to wait to receive the return instructions?
GuyScharf
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August 1st, 2015 22:00
In fact, the problem occurs with no USB connections at all.
Received return paperwork by email today so will ship monitor back after the weekend.
It's a pity -- the screen and overall appearance are very nice. It just doesn't work right.