Wavy Picture problem

[prpr]

the analogue output from the Humax is 576-lines - even the StDef channels are 720-line.

SD channels have 576 lines. I don't know why you think they are 720.

I don't know the impedance of the signal pairs in Cat5 off the top of my head, but maybe - just maybe - they are compatible with the impedance of the video system.

It's 100 ohms +/- 15. Obviously this is not 75 ohms which everything else expects to work on and it's not ideal but it's probably not the major cause of the problems.

Twisted pairs are what we call "balanced line" though, and ideally require a different drive from the single core of a coax cable.

Unbalanced drive and termination will destroy the balance of the cable rendering it susceptible to interference. And as there is no outer shield to keep it out, who knows what you're gonna get...

 

[Black Hole]

SD channels have 576 lines. I don't know why you think they are 720.

A simple memory glitch. I will revise my previous post, thanks.

 

[Yeldarb1967]

Hi All
It was as Ezra suggested in the first suggestion an electrical power problem from the 12v patch panel supply. We have replaced the 12v transformer and it works well again. My man who came in to fix it called it a tear in the picture. He also reinforced some of your views that I should have a converter at each end of my cat5 cable to provide HD quality pictures.
Thanks to everyone for the their suggestions.

 

[Trev]

OK so I was nearly right. Just got the wrong PSU But I still bet it was the smoothing caps in the 'transformer' (PSU).

 

[Black Hole]

I still wonder what this patch panel is, even more so if it requires a power supply!