U2415, flashing/blinking on and off somewhat randomly

Question

I've seen some discussions dating back to 2015 and 2016 of flashing screens / screens that go blank; I bought a new U2415 anyway a week ago, thinking that Dell would surely have fixed the problem by now -- it's been 4-5 years! (The box says my monitor was manufactured in Nov. 2019.)

Apparently not. If there's a design defect, does Dell just leave it in production until the model is discontinued?

The flashing/blinking problem seems somewhat random, but it can be "reset" by turning the monitor off for 10-15 seconds and then turning it back on. It will then go for several hours -- often 8-12 hours -- before starting to blink again, which made me wonder if some component could be overheating and doing a self-shut-off. Once it starts, sometimes the blinks occur every few minutes; other times the cycle is maybe 3 second on, 3 second off.

I'm using the HDMI input #1 on the monitor. I have a Dell Inspiron 3847, but it didn't seem from inspecting the graphics properties that it could go over regular HD resolution (1080 vertical), so I bought an Asus GT710 card at the same time as the monitor to ensure I could drive 1200 lines to match the U2415's native resolution. (Yes, I know that's a lame card, but I had only two criteria -- 1200 lines vertical or more, and passive cooling because I *HATE* fan noise. The latter restricts me to low-powered cards.)

For reference:

Dell Inspiron 3874 as noted above, Windows 7 Pro (64-bit). Yeah, I know. Win 10 coming after I can stop futzing with the hardware.
Asus GT710 card with 2GB GDDR5. it has 1 VGA output, 1 DVI output, and 1 HDMI output.
I'm using an HDMI 1.2 rated cable to connect the HDMI out to the monitor HDMI input #1.
I have an old Samsung monitor connected to the GT710 DVI-to-monitor-DVI as a second monitor. (Before the DVI cable arrived today, it was connected via VGA cable. The U2415 flashing occurred in both circumstances.)

No, I *don't* want to do a monitor reset to factory defaults because one of the main reasons I purchased this monitor is because it supposedly has been color-calibrated at the factory. I don't want to risk losing any of their tweaks. Also, as far as I know it is set exactly as it came from the factory, except that it defaulted to DisplayPort input and took a restart or two to recognize that it was connected to HDMI -- now it flashes the HDMI connection immediately each time it's turned on.

Because the problem can take hours (and sometimes a couple of DAYS) to manifest after power-cycling the monitor, I haven't tried switching to the monitor HDMI #2 yet, but I'll probably try that this evening. But I won't know if that's had any effect for a day or so.

Key question -- Forget the diagnostic steps with cable swaps, port swaps, etc. What fundamental engineering characteristic of this family of monitors (and I believe even other models of Dell monitors) could cause this to be such a frequent, consistent problem reported by customers over so many years of production?

I'll post a follow-up note after some time has passed with the HDMI cable in the other monitor input.

Thanks.

rsteer · Accepted Answer

Long-term update (10 months): The monitor flashing on and off is not as frequent as it was when it was new, but I also now try to make a point of giving the monitor a "rest" by turning it off if I take a break or run an errand so that it's not on continuously for 8-12 hours as it was initially. (Simply letting it turn itself off during inactivity never helped.)

Note for product engineers

I *DID* discover one interesting thing that may hint at the engineering problem that causes this glitch across multiple Dell monitors. Once the monitor starts blinking, turning it off with the touch-switch for 10-20 seconds sometimes would fix it, but not most of the time. However, the success rate is much higher if I *unplug* the monitor (power plug) and *then* press the power touch-switch, which turns on the power light momentarily as any power stored in the monitor power-supply drains. (That prevents the circuitry from staying partially-powered in standby or "quick start" mode.) After the power light fades off, I reattach the power cord 5-10 seconds later, and turn the monitor back on. That generally solves the problem for at least several more hours.

jphughan · Answer

@rsteer I can't account for the blinking display behavior, and having supported an office that has over a dozen U2415 displays, I haven't heard any reports of this behavior except an occasion where the underlying cause turned out to be with the system and the fix was to install a firmware update. But in terms of resetting to factory defaults, I'm fairly certain that resetting to factory defaults will not cause you to lose factory calibration. I believe the per-display factory customizations are set in the hidden Service Menu. It doesn't really make sense to me that Dell would sell a display that said, "We calibrated this at the factory for you, but if for whatever reason you ever decide to reset its settings, then you'll lose that benefit that might well have been a major reason you decided to buy it in the first place. And if you ever change the color settings yourself and can't remember what the original settings were, then too bad for you.".

As usual, you are correct! The factory calibration is saved in the Dell service center internal FSM (Factory Service Menu), not in the user accessible OSD (On-Screen Display) Menu, page 37.
DELL-Chris M

rsteer · Answer

@jphughan , @DELL-Chris M -- Good to know about not losing the calibration if I do a reset -- Thanks!. But since I haven't changed any settings yet since unboxing, I wouldn't expect that to do much.

I said I would post a follow-up after trying the HDMI #2 input on the monitor. THAT didn't solve the problem -- the monitor worked for a while, but when I came back to it after several hours the screen stayed black even while my second monitor woke up. And unlike my experience with HDMI #1 input, turning the monitor off for a few seconds didn't restore the screen. Not even after a couple of on/off cycles. So I switched the cord back to HDMI input #1 and the picture came on fine. So HDMI #2 seems really messed up -- but I only need one HDMI input...

No flashing since I switched the HDMI cable back to monitor input #1, but it's been on less than 12 hours and sometimes it takes longer than that for the flashing to manifest. We'll see about the next day or two.

DutchTennessean · Answer

@rsteer​ Hello from the future. One of my U2415s just started doing this, unfortunately, and swapping out the DP cable did not work. But your short term workaround/fix does seem to postpone the flickering so far, so thanks for posting it. I know it's been 3 years since your last update. Did you ever get this fully fixed?

Monitors

U2415, flashing/blinking on and off somewhat randomly

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