Extending an LCD LVDS

[deRost]

I am extending the LVDS cable between the LCD and the driver board to fit into the lid of a Pelican 1600. It's an RCA RLC2253 screen, 22", has an external power supply, HDMI, VGA, component inputs, headphone jack in/out, and with the bezel attached it fits the Pelican lid almost perfectly.

The cable is not a thin ribbon, rather it is a group of 5 twisted pairs (30awg?) blue/wht, 7 black, and 3 red. I used 5 lengths of USB as the wire size was correct, kept the twisted pairs grouped in the same few USB sections, and bonded the shields to the original shield.

Originally the problem was with some minor color artifacts when viewing my X360 through HDMI. I tinned the wires, overlapped the ends, and soldered them. So I thought my color artifacts were being caused by attenuation from the solders. So I re-soldered the twisted pairs as a butt splice (tip-to-tip).

Now my artifacts are a little worse, and the screen flickers. Perhaps I should try to re-splice the original section back together and keep the driver board behind the screen?


Thanks.

edit: clarify the LVDS cable

[Snow_Cat]

Soulds like it may be crosstalk, you could try running only one pair/shield or try network cable w/ aluminum tape/foil for shielding.

Aluminum will not solder to copper using conventional methods, so you will need to clip/crimp it to grond/ref.

Though keeping the driverboard close to the screen is the safest option.

[hailrazer]

Did you keep the pairs twisted ? That is necessary.

[Snow_Cat]

I would not be surprised if the USB bundle is not actually twisted inside its shield.

[deRost]

I pulled the cable apart last night and began splicing Cat5e in it's place, using only the blue, orange, and green pairs as the twist ratios were tighter than the brown pair.

I took a look at the USB wires as well, and you are right, they are not twisted inside. Actually, in one section of USB one pair was twisted -- green and white. I had originally spliced blue/wht on the LVDS to black/wht on the USB, and the next blue/wht to red/green on the USB. So I had two whites essentially twisted together. So I think you are right about the crosstalk... big time.

Anyways, I just bought a helping-hands finally so I will continue with the Cat5e. If I had a spare HDMI cable, that would be better as they have individually shielded twisted pairs.

[deRost]

I re-built my LVDS extension with Cat5e, grouped the signal pairs together in a common shield (woven shield from a VGA cable), and put ferro magnet around them -- one at each end.

The cable is now three feet long, and the image is perfect! In fact, I had a dead pixel as purchased from the store. After playing MoH on the newly extended screen, it disappeared. Win win!

Thanks for the advice and awesome forums all.

[kibble]

Sounds like you did a good job on that! I meant to reply to this thread some time ago when I came across it, but it sounds like you got it all straightened out. I made an about 4ft LVDS extension myself several months ago with an inline voltage regulator and like you, I had signal issues at first until I properly shielded everything. I used 10 pairs of stranded parallel printer cable for mine and the braided sheilding, here's a pic: