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E7240 Loses video when switching input on a VGA KVM switch
I've started to encounter this, curious, issue with a new Latitude E7240 ultrabook.
The hardware in question is a Latitude E7240 (docked to a simple E-Port2 port replicator) and connected to an external monitor via a VGA KVM switch (Edimax UAK2).
I have the KVM switch set up so that I can control both a desktop PC and the E7240 (when docked to the E-Port) with a single keyboard and mouse (and use a single monitor to display output from either device).
If I start up the (docked) E7240 and the KVM switch is set to accept input from (and display output from) the desktop PC, the desktop is recognised. If I switch to the E7240, no VGA output is detected (clack screen).
If I start up the (docked) E7240 and the KVM is set to accept input from (and display output from) the E7240, VGA output from the E7240 is properly detected. Switching to the desktop then back to the E7240 results in the same result as the first scenario.
After the second scenario, pulling the VGA cable from the back of the E-Port and reattaching it restores VGA output.
What's particularly confusing is that this exact same setup has worked with my previous Latitude E5420 (note - in that configuration I was using a first generation E-Port advanced, the E-Port was replaced during the upgrade as I do not believe the original e-port is supported for use with the E7240).
Can anyone suggest any potential solutions to this issue?
PaulS1000
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February 15th, 2015 07:00
I have exactly the same issue and I've tried it with multiple port replicators and multiple KVM switches - always the same result. If you boot or wake the E7240 from standby with the KVM having the E7240 as the source, all works fine. As soon as you switch to another PC and back again, the video is lost.
I also previously had a E5420 which worked without issue with the same setup.
Has anyone found a fix for this, it's driving me crazy!
PaulS1000
2 Posts
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February 15th, 2015 07:00
Forgot to mention, my PCs are all connected via DVI