Question External monitor is blank/black when laptop is charging

Apr 14, 2020
I have Dell Inspiron 15 7570, Intel Core i7 8th Gen
With graphic card Intel UHD 620 & Nvidia Geforce MX940.

I'm trying to connect an external monitor ( LG Flatron E2350T) to the laptop. This monitor has a DVI connector so I'm using DVI to HDMI adapter to connect it to the laptop.

When the laptop is charging there is a blank/black screen at the external monitor, although it can be detected at Device Manager & Display Settings as the second monitor.
I have tried to switch between Project types (Windows + P) and still black, Also via display settings.
I have tried to check with other laptop and connect it the same way and it works there so I don't think the problem comes from cable/adapter.
Updated the firmware of the external monitor to the latest & all graphic drivers.

When I unplug the laptop's charger the second monitor shows "CHECK SIGNAL CABLE" and when I re-plug just a black screen/blank.
I also formatted the laptop, didn't help.

I tried to connect the laptop to the TV screen only via HDMI cable and it works.

BTW - when the charger is plugged/off and monitor connected, I can drag files to the external monitor (when in External mode projection) but cannot see it because the monitor is black/blank/CHECK SIGNAL CABLE.

Does anybody have an idea why it doesn't work?
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May 19, 2020
I have the same problem with a Inspiron 15 7560 Intel i7-7500U 7th Gen Processor.
With graphic card Intel UHD 620 & Nvidia GTX 940MX 2GB GDDR5.

Done the same as you- uninstalled and reinstalled all relevant drivers, tried different cable and screen combos. All with no change.
As you say the display settings recognize the monitor as it allows you to change from 'extend' to 'duplicate' screen modes but still my additional monitor stays black with no signal even though I can drag files over (into where the 'extend' would usually let me but there is no picture at all on my second monitor.)

I suspect that there is an issue with the Nvidia 940MX because in the 'Nvidia control panel' (left click on desktop/background) my 'set PhysX configuration' shows both displays going to the intel integrated CPU/GPU and nothing to the Nvidia. I do not know how to set the external display to run on the Nvidia card.

Like 6months ago it used to work without a hitch and I could use an additional monitor.

I unlike you see no difference between charging and not charging. Just doesnt display to the external screen in both cases.

Please let me know if you fix the issue.