Blinking montior - VGA to HDMI issue?


I have an older Dell 24" monitor (model 2407-WFP HC) manufactured in Nov 2007. I have it connected to the UD-3000 via VGA to HDMI adapter. My laptop is an Acer Aspire S7 (model 391) running Windows 8.1. The monitor is connected through the UD-3000 to my laptop and I am experiencing constant screen “blinking” issues when the lid to my laptop is closed, and less frequent (but still intermittent) blinking when the lid is open. Display is set for “duplicate” and power option is set for “do nothing when lid is closed and plugged in” (that is, do not turn off, sleep, or hibernate).

Previously, I had the monitor connected directly to the laptop via VGA to HDMI-micro adapter. My display & power settings allowed me to view the external monitor when the lid of my laptop is closed as well as when it is open in the same settings noted above. I have downloaded the most recent driver and rebooted the laptop. Suggestions on how to fix? Or is it simply old monitor compatibility issues?

Thank you.


Hi Cindy,

Thanks for posting. I’d be happy to help answer your question.

It is possible that the problem is related to the age of your display. You mention your monitor is from 2007 and were kind enough to post the serial number, but not the specific model of the monitor. Can you let us know the model?

Looking at the specs I found for your laptop online it only offers the micro HDMI output. You mention you were using a micro HDMI to VGA adapter and that was working well, and now you are using the UD-3000 dock with the DVI-VGA adapter.

If you reconnect the monitor directly using the old adapter, does the screen still blink as described?

Does the monitor happen to have a DVI input (as opposed to VGA)? If so you could try using a DVI-DVI cable from the dock to the monitor to see if that changes the behavior.

Let us know the additional information when you have a moment and we can go from there.

Thank you,

Plugable Technologies


Hi Bob - thanks very much for the quick reply. Answers:

  1. Model of monitor is 2407-WFP HC. (I had updated the post previously with this info but guessing it was after you had gotten my original inquiry.)

  2. If I connect the monitor directly to the laptop via micro HDMI to VGA output adapter, it works just fine. No blinking at all.

  3. I have a VGA-DVI cable but no DVI-DVI cable. I can go pick up one today, that’s easy.

Thank you,



Hi Cindy,

Thanks for getting back, and thanks for updating the post with the model of the monitor (You are correct I missed your update, sorry about that).

The test with the monitor connected directly to the laptop hopefully indicates that the monitor is not having a hardware problem itself.

Testing with a regular DVI-DVI cable would be the easiest first step. Let us know the results when you have time and we can go from there.

Thank you,

Plugable Technologies