Over the last year I have been fighting with a rolling video line issue with nearly all of the K4’s I have installed since the product first came out.
I have also had trouble with rolling lines appearing on other types of displays in any given system, for no particular reason as long as at least 1 K4 is involved in the video chain somewhere
I tried everything to get rid of it to no avail, Finally I found a low cost video ground isolator, Which gave instructions to the effect that the isolator should be connected near the source. Well that did not work, so I installed it backwards at the k4 itself and the rolling lines disappeared, well actually the rolling lines on every display in the house disappeared.
I though hey this is great, problem solved, the K4 has been dumping a bunch of junk into the whole system and this little cheep part fixed it.
BUT! Then I put the faceplate back on the K4 and the lines came back worse than before, I thought what the hell is this, so I took the cover off and the lines went away on all of the displays again. Then I put my thumb in front of the light sensor and the lines came back, so I grumbled how stupid is this. So I deactivated the light sensor in the software and whole thing works great.

Obviously there is something seriously wrong with the K4 light sensor circuit that is leaking junk into the video circuits, I have one system that was so bad that you could see red hash visibly appear on a Samsung DLP every time you executed a command for the K4.

Note that just turning off the light sensor does not solve the problem; you have to turn off the light sensor and install a video ground loop isolator.
I found the video isolator here [Link: 2mcctv.com]

great info. thank you!

R u going to forward this to RTI?

Please DO!

I've been battling the same issue on our demo system and 1 clients' home.

I noticed that when the screen dimmed to the "idle" mode... the lines came on. SO I put the thing in FULL ON mode and it cleared up to 90%. (basically same thing you did...).. I'll have to try an isolator for the other 10%

My guess is they should be able to fix this issue at the hardware level somehow...now that we have narrowed the search down a bit.

Thanks for the tip on the light sensor

Had similar problem with lines: cleared up by four IsoMax isolators connected at the source (light sensor was already turned off)

my only other issue is the K4 will not remember passwords for web sites after it is rebooted/powered down (edit: unless I am missing something?)

Awesome! That had been driving me crazy (and there is no ground prong to snip off!)

I'v never really tried using these on LCD sets, but do they work for component vid? Would one need three- Y, Cb, Cr? Or just one on the Y?

I only installed one composite filter on the K4 side, Then deactivated the light sensor. All the other TV displays cleared up when I did this, I emagine, you would have to do this with every K4 that is in the system to correct the problem. I have not had to put a filter on the component side of anything yet, but I have been curious If I could use 3 of these low cost filters in a component video senario? I dont know if the band width is great enough So I am going to give that a try as well.

Taked with brett about this today, They are are going to take a serious look at this problem. Speaking of problem. I fixed another customers K4 and DLP display with this technique today, great picture now and no scrolling lines. Just 4 more customers to go and they should all be better.

I'm wondering if the problem is in the light sensor... or in the dimming "mechanism".

In other words, will the problem still be resolved if you:
Disable the light sensor...but set the light output to say 50% all the time..... or disable the light sensor and set "in-use" to 100% and "idle" to 50%?

This may be critical for an out of town job I have coming up...where the K4 is in the bedroom.... I'd like to be able to dim it when not in use.... but still have good video.

I had to turn the sensor off to fix the problem

I am curious about that because of other TVs in a system without an inwall of any kind having the rolling lines. I absolutely hate having to go through a rack loaded with distro/theater gear to find a ground loop source....

As general rule, try to maintain only one grounded component in the entire system, remove the grounds from all displays and components except for one, which in my case is usually the video switcher, the shield in your video cabling will carry the ground as a single path back to the grounded device.

Can you still use a dimmed "idle" mode then?

Does the panel show the scrolling bars when the panel is dimmed in idle mode?

This feature actualy seems to work OK, I beleive this is because it is based on a timer and not the light sensor

sorry to bump an old thread...

installed a new K4 and still have rolling lines unless I turn off light sensor (it helps but I still have some rolling on some screens, even with isolation)

RTI still has no fix for this?

Video isolators do not help: turning off light sensor helps it but I want to use the light sensor