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Dixit
Punch Card
Posts: 35
Registered: ‎10-03-2009
Location: Atlanta
Views: 6,438
Message 1 of 13

T420 - external Display doesnt wake from sleep (when power savings shuts display off)

I have a T420 with a Mini Dock Series 3 (433710U).  The External Display is a 30" Dell U3011 monitor connected to the Dock via DisplayPort.

 

As Im dealing with another issue (another thread) the Bios is set for Discrete Graphics only as the Optimus mode currently has a bug which cannot drive this 2560x1600 resolution display.  Now that I have a workaround, I have another problem.

 

When the power savings in Windows7/Power Manager turns the display off (for me its set for 10mins), If I come back 20mins later, shake the mouse, the Dell Display acts like its turning on (LED light turns on blue to indicate signal) and then message flashes on the screen from the Dell monitor stating that its going to sleep.  So now I have a Black display (monitor went back to sleep).

 

I can open the Lid on the laptop (forgot to mention I dont dual display, I just use the 30" exclusively and close the lid on the laptop on the dock) the screen on that shows up. Close the lid again, the monitor does the same thing where it acts like its turning back on and just goes back to sleep. 

 

Someone mentioned a similar problem where they believe the laptop is not sending the correct DPI to the monitor causing it to not be able to display the output.  They mentioned that doing a CTRL+ATL+DEL when the laptop lid is opened, and then closing it again works.  Thats works for me, but only once.  After that, if it sleeps, I have no monitor to use.  Only way to correct it is to simply undock and redock the laptop, which is a mess since all my connections (network) get cut.

 

Is there any real fix to this?  Is there a way to hardcore this DPI issue (if thats the issue)?  The drivers on the laptop are using the latest 275.33 Nvidia drivers so cant be that.  BIOS is on latest one, so cant be that either.  Cant be the monitor as it doesnt have this problem with my older laptop.  Even disconnecting the DisplayPort cable and reconnecting it doesnt fix it.  The laptop just seems to be stuck on the wrong signal to the monitor.

 

My T61 with a dock never had this problem with this same 30" monitor.  This T420 is nice but giving me more issues trying to use external display then its worth.  Sad that a new laptop cant even do what the T61 could do in that sense. 

 

Dixit

Former Employee
Posts: 2,437
Registered: ‎04-10-2011
Location: Malaysia
Views: 6,335
Message 2 of 13

Re: T420 - external Display doesnt wake from sleep (when power savings shuts display off)

hey Dixit,

curious to know, let's say if you uninstall Power Manager and use windows built in power management; does the same issue occur ?

also what happens if the external monitor is connected directly into the T420's display and not with the docking station ?






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glenp
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Posts: 1
Registered: ‎08-04-2011
Location: Canada
Views: 6,328
Message 3 of 13

Re: T420 - external Display doesnt wake from sleep (when power savings shuts display off)

Having exactly the same issue with T410S, connecting to the Mini-Dock with 20" Dell monitor. Monitor flickers like it is going to connect (including the light on my USB stick which is attached to the monitor) and then it goes back to sleep. Takes multiple reboots and trial and error to get the monitor to display again.

Dixit
Punch Card
Posts: 35
Registered: ‎10-03-2009
Location: Atlanta
Views: 6,319
Message 4 of 13

Re: T420 - external Display doesnt wake from sleep (when power savings shuts display off)

Serge1410,

 

The issue does happen when directly connected to the Lenovo T420 as opposed the Dock, I tested this for a few days and same issues. 

 

Instead of testing this Power Management uninstall (which honestly I dont think is the problem), Im running down another path which might be promising.  Ive found a thread on dell forums that show this monitor via DisplayPort has the same isses with HP laptops, even Dell Laptops (dock or no dock), and even MacBooks and Mac Minis.

 

One fellow member mentioned he managed to fix the issue on his MacBook by using another DisplayPort cable.  One made by Circuit Assembly.  Turns out that the cable included by Dell is most likely not a Vesa 1.1a compliant.  Someone mentioned that the poorly made cables have something with the pin 20 shorting out with 21.  Even cabled from Monoprice exibit this same issue. 

 

Im waiting on Circuit Assembly to have the cables back in stock to try this out.

 

Dixit

ashirusnw
Fanfold Paper
Posts: 12
Registered: ‎06-27-2008
Location: USA
Views: 6,158
Message 5 of 13

Re: T420 - external Display doesnt wake from sleep (when power savings shuts display off)


@Dixit wrote:

Serge1410,

 

The issue does happen when directly connected to the Lenovo T420 as opposed the Dock, I tested this for a few days and same issues. 

 

Instead of testing this Power Management uninstall (which honestly I dont think is the problem), Im running down another path which might be promising.  Ive found a thread on dell forums that show this monitor via DisplayPort has the same isses with HP laptops, even Dell Laptops (dock or no dock), and even MacBooks and Mac Minis.

 

One fellow member mentioned he managed to fix the issue on his MacBook by using another DisplayPort cable.  One made by Circuit Assembly.  Turns out that the cable included by Dell is most likely not a Vesa 1.1a compliant.  Someone mentioned that the poorly made cables have something with the pin 20 shorting out with 21.  Even cabled from Monoprice exibit this same issue. 

 

Im waiting on Circuit Assembly to have the cables back in stock to try this out.

 

Dixit


Dixit, did changing the DisplayPort cable solve your problems?

 

Interested as I'm considering buying a T420s to work with Docking Station and 30" display

Dixit
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Posts: 35
Registered: ‎10-03-2009
Location: Atlanta
Views: 6,144
Message 6 of 13

Re: T420 - external Display doesnt wake from sleep (when power savings shuts display off)

I havent tested those cables from Circuit Assembly since I ended up with a DisplayPort to Dual Link DVI adapter to use with my KVM (which is dual link dvi capable).  So been working fine on that but it has artifacts and what not from time to time, so I need to get that cable when it gets back in stock and try it.

 

Dixit

Dixit
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Posts: 35
Registered: ‎10-03-2009
Location: Atlanta
Views: 5,963
Message 7 of 13

Re: T420 - external Display doesnt wake from sleep (when power savings shuts display off)

I want to kick that back to the top to see if this is a bug in the firmware or drivers of the video.  Because initially it was thought it was possibly the DisplayPort cable as some others suggested on the Dell forums, well turns out that is not true.  I bought a new Circuit Assembly cable and still dont work.  The concept on that was that pin20 for the DisplayPort is not to be connected (so if you ohm tested both ends with probes connected to pin20, you should get a short, or not connected in a continuity test).  Well both of my cables (the Circuit Assembly and the original Dell) both are fine in that aspect.

 

But they both still have the same issue in that if the laptop via the Mini series3 dock or directly connected to the T420 (with Optimus enabled) via displayport cable, if the laptop tells the monitor to go to sleep due to power settings, then 9 out of 10 times it will refuse to wake up the monitor.  Even unplugging the DisplayPort cable and plugging it back in doesnt help.  Sometimes opening the lid on the laptop and closing it gets it to work (which is the 1 out of 10 from above). 

 

Someone mentioned its not correctly sending it the signal out of sleep/wake.  So is anyone else having this issue?  I know the other person on this forum mentioned they are.

 

I initially stopped using the DisplayPort cable to use the DisplayPort to dual link DVI active adapter and then from there the dual link DVI goes to my Dell 30" monitor.  Thats been working fine in that it never has the sleep/wake issue, never.  However it has other issues in that alot of times if you full screen a hardcore image or something graphics intensive like a flash page, it causes the entire screen to go blurry or have all these green/red pixels.  I think its because this active adapter doesnt have enough juice (even though its tapping power from a USB port) to handle driving the 2560x1600 resolution.

 

Dixit

ashirusnw
Fanfold Paper
Posts: 12
Registered: ‎06-27-2008
Location: USA
Views: 5,796
Message 8 of 13

Re: T420 - external Display doesnt wake from sleep (when power savings shuts display off)

If I use a regular dual-link DVI cable from the Mini Dock (Series 3, 4337) from a T420s (with Optimus) to my 30" monitor, should it "just work"? Is it only displayport that's giving you such problems?

Dixit
Punch Card
Posts: 35
Registered: ‎10-03-2009
Location: Atlanta
Views: 5,792
Message 9 of 13

Re: T420 - external Display doesnt wake from sleep (when power savings shuts display off)

The DVI port on the Series3 4337 dock is not dual link capable.  Read up on the maximum resolution for that port on the dock.  It comes in at only 1920x1200.  Thats not enough to use native resolution on my Dell 30" U3011 monitor (requires either dual link DVI or displayport).

 

http://support.lenovo.com/en_US/product-and-parts/detail.page?DocID=PD014560 Here are the specs of the Dock.

 

What boggles me is that my old dock for the T61 (which is what got replaced with the T420) even had the capability of doing dual link dvi.

 

So Im stuck on using the displayport connector, however the sleep/wake issue with this monitor is still present.

 

Dixit

 

corndogankles
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Posts: 2
Registered: ‎12-14-2012
Location: Wichita, KS
Views: 4,516
Message 10 of 13

Re: T420 - external Display doesnt wake from sleep (when power savings shuts display off)

I'm having the same issue with a lenovo T420 connected to one external display. Anytime it is put to sleep it has to be rebooted in safe mode, then restarted again.

Has anyone figured this out?

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