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07-08-2009

RTP, NC

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T400 will not recognize Benq monitor thru my TRENDnet KVM switch

2009-07-08, 20:23 PM

I get an error message "Your computer is not attached to an external monitor" when I try to connect to my analog monitor thru a TrendNet 4 port KVM switch (TK409K) to my T400 .... USB keyboard and mouse plus sound all work fine thru the KVM switch .... desktops on other ports (a NetVista and a ThinkCenter) are all OK and can use the monitor correctly ....

 

My prior laptop (T41p) was also able to use the monitor thru the same port on the KVM switch .... only change was to replace T41p with upgrade to T400 .... if I bypass KVM switch and connect the monitor directly to the T400, all is OK .

 

I thought the monitor output from the laptop was solely outbound, but the error message seems to indicate that it has a way of detecting whether anything is attached to the monitor output connector on the T400. My suspicion is that whatever info the T400 expects when a monitor is attached is not getting back thru the KVM switch, but ....     :smileymad:

 

Any ideas, hints, advice would be greatly appreciated .... thx in advance.

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1 Posts

07-23-2009

USA

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Re: T400 will not recognize Benq monitor thru my TRENDnet KVM switch

2009-07-23, 21:45 PM

I have the same problem but with an Acer monitor.  I (temporarily, must be done each boot) solved the problem by connecting monitor directly to docking station, Control Panel->Display Settings->Settings->Extend my Windows desktop onto this monitor (this gets the 2nd monitor working), then connect monitor to KVM.

 

There must be a bug in the video sensing code of the graphics driver when trying to enable 2nd monitor when it's plugged into KVM.  I updated my Intel Series 4 graphcs driver to the latest but it made no difference.

 

Message Edited by df8qz on 07-23-2009 02:46 PM
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1 Posts

08-04-2009

Bothell, WA

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Re: T400 will not recognize Benq monitor thru my TRENDnet KVM switch

2009-08-04, 4:14 AM

Hmmm...I get the same sort of symptoms.

 

I've got a 22" Acer LCD connected to a TK-409K 4 port switch.  I tried shutting down my T400 Vista laptop, docking it and switching the KVM over to port #3 (where I've got the wires hooked up that are connected to the VGA & USB port of my docking station).  Then I turn on the T400 and it doesn't appear to find my Acer monitor.  Going into display settings shows display 2, but the only choice for resolution if 800x600, and enabling "extend the desktop onto this monitor" doesn't show anything on the monitor.  Mouse & keyboard both work.

 

Then...when I switch the KVM over to port #1 (where I've got a Vista desktop), my laptop's LCD switched to 800x600 resolution (it was at 1440x900) and I thought that was weird.  So, I went in to display settings and set display 1's resolution back to 1440x900 and I now had the option to set display 2's resolution to 1680x1050.

 

Then, I switched my KVM back over to port 3 and I (momentarily) see my laptop's background displayed on my Acer monitor.  Both displays flash black and Acer monitor stays black, while laptop comes back.

 

Then if I switch  back to port 1 again, my laptop pops up a dialog titled "Full Screen Magnfier in Multi-Monitor mode" explaining how I can move windows from primary display to secondary by pressing Fn+Space.

 

Some things I haven't tried yet...

 

* Bypass the KVM and see if the laptop can drive VGA or DVI outputs from the docking station properly.

* Use my own VGA cable instead of the one bundled with the KVM.

 

Ideas welcome...

 

Thanx,

Scott

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4 Posts

07-08-2009

RTP, NC

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Re: T400 will not recognize Benq monitor thru my TRENDnet KVM switch

2009-08-11, 15:02 PM

Update: no permanent solution.

 

Talked with support at TRENDnet, and after much back and forth, they finally said they did not support the T400   :smileymad: . So my workaround is to bypass the KVM for the monitor when connected from my laptop. Other two desktops connected thru the same KVM switch all continue to work OK. I just have to swap cables when I switch to my laptop.

 

No technical explanation from TRENDnet guy as to what is actually happening .... my guess is still that the T400 needs to "see" the monitor thru the KVM switch, and that is what keeps me from being fully functional.

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4 Posts

07-08-2009

RTP, NC

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Re: T400 will not recognize Benq monitor thru my TRENDnet KVM switch

2009-08-11, 15:56 PM

another idea: I believe the T400 connected thru the docking station has a DVI output as well as a VGA .... and my monitor has a dual input capability (VGA and DVI) .... so I think I'll get me a DVI cable for the Laptop/dock --> Monitor connection (thus effectively bypassing the KVM switch) and use the KVM --> VGA connection for my other Desktops .....

 

hmmmm, might have found the solution to the dreaded cable swapping

 

now to find a cheap DVI cable  :smileyhappy:

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4 Posts

07-08-2009

RTP, NC

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Re: T400 will not recognize Benq monitor thru my TRENDnet KVM switch

2009-08-18, 14:56 PM

Problem solved (well, I guess it's really a work-around) ....   :smileyhappy:

 

a DVI-D cable from my laptop docking station to my dual input monitor allows me to get the video signal directly and get the input from the kbd and mouse thru the KVM switch .... and my two desktops continue to work thru the KVM switch to the analog input of the monitor

 

I never found out what signal wasn't being passed from the monitor to the laptop thru the KVM switch .... but the laptop clearly did not recognize that there was a monitor attached thru the KVM

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