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Blue Screen Again
Posts: 1
Registered: ‎08-24-2010
Location: United Kingdom
0 Kudos

T400 External Display does not work with EDIMAX EK-UAK4 KVm Switch

Good afternoon,


I have a T440 (6475-WJE) :


  • BIOS v3.19
  • Windows XP Pro (2002) SP3

..and I am trying to use an EDiMAX EK-UAK4 USB KVM switch.  The external display I have is an LG Flatron W2246T


When I connect USB Mouse, Keyboard and Screen direct to the T400 and boot, everything works fine.


When I connect via the KVM switch, the display is not sensed by the T400 and therefore only the keyboard and mouse work via the KVM switch.


Both of the other machines attached to the KVM switch work spot on (ie. Screen, keyboard and Mouse are fine).


Any ideas ??



Fanfold Paper
Posts: 6
Registered: ‎07-14-2010
Location: Australia
0 Kudos

Re: T400 External Display does not work with EDIMAX EK-UAK4 KVm Switch


I have had similar problems with some notebooks (not just T4xx). I was using a 16 port KVM over IP switch from HP (with virtual media USB dongles), which was essentially a rebadged Avocent. Like you, the T410 I was testing would not output to the KVM. Pressing th FN+F7 (I think) to switch between display and external, would either do nothing, or cause the KVM attached monitor to go black, then into standby, go black, then into standby.

I initially thought it was something to do with EDID see this post:

So I bought a VGA EDID emulator from:

Which unfortunately did not work. At the same time, we were experiencing problems with the KVM switch power supply, so I booked a call with HP, and they replaced with their G2 KVM switch. This was also an Avocent, but had a much better interface (full web based), and with this KVM, the notebook was able to work.

I did go back and test the old KVM before I sent it back, and found that if I used a 'normal' USB dongle, rather than one that had virtual media, then it would work. Same with a PS2 dongle. Not sure why, but the newer dongles didn't seem to like the switch, even though they would work with any desktop etc.

Anyway, hope this gives you some direction.