07-17-2012 01:39 PM
When I use the VGA port and plug in the power cable into my T430 I notice faint horizontal lines flickering on the external monitor, in areas of certain shades of gray. It is faint, but visible. I have auto-adjusted the external monitor.
The flickering is visible even when the laptop is not plugged into a power outlet, but not as visibly.
This is quite disappointing, after having come from an HP *netbook*, which displayed none of these problems. Is this normal?
07-17-2012 02:22 PM - edited 07-17-2012 02:25 PM
I had the exact same problem with my T61. Turns out to be noise coming from an earth loop. So, I isolsated the earth pin on the power supplly and the problem dissapeared.
Disconnect the PSU and see if you still have problems.
If the problem dissapears when running from battery then consider removing the noisy earth loop.
EDIT: Just realised that your getting the same problem running on battery.
07-17-2012 02:51 PM - edited 07-17-2012 03:09 PM
There is actually no grounding connection on the power plug, so I don't think that's what's causing it.
Also, on second look I think the much weaker flickering I see in some shades of gray when not plugged in may be just be the 6-bit monitor dithering doing its thing. I admit I never looked that closely for flickering before seeing the stronger one from the PSU.
It's not a dealbreaker, but it's a little disappointing this is happening, in the exact same setup that it wasn't happening with a different, much cheaper, machine.
07-17-2012 03:14 PM - edited 07-17-2012 03:15 PM
Yea, I think the noise enters the machine via the Signal (Center pin) on the PSU connector.
It didn't matter if I isolated the earth pin, at the mains, on the external monitor or the T61 PSU, just breaking the earth loop completely cured the problem.
07-25-2012 09:38 PM
Unfortunately, I noticed the same issue on my brand new T430 as well as that of a friend (identical configuration). The problem *almost* completely resolves when the PSU is disconnected, although some faint horizontal banding/waves are noticeable.
How might you suggest I disconnect the ground loop on my PSU connector? Might there be another way around.
I know that using a mini displayport to DVI (or HDMI) adapter would solve this problem, but it's still disappointing nonetheless. This is the first laptop I've owned with this particular issue. One would think that as builders of business-class laptops, Lenovo would ensure that its products could be used to display presentations flawlessly...
04-15-2013 09:26 AM
I'm currently experiencing the exact same thing with both a 90W and 65W lenovo power adapter, both ungrounded. Problem is reduced when laptop is not plugged in, but is still present.
Starting to think that it's a defect in the laptop and that it will need to go in for repairs (it's brand new).
06-10-2014 08:13 PM