1 camera split to 2 multiplexors - horizontal black bar

[Alexg]

Got 2 feeds from one camera, each feed splits at the camera with a bnc Y splitter.

1 feed runs to a Tecton multiplexor, the other to a Borsatec DVR.

On both screens I get a very faint horizontal bar which goes from left to right really quickly.

I can't find anyway to adjust the termination settings in either the mux or the DVR.

Any suggestions? everything is on one TNS earth system.

[breff]

Any room to fit a 2way Video Distribution Amp at the camera?

[Alexg]

Ooo tricky, the housing is full, guess I could add another IP65 box & put it in that. I've managed this in the past without an amp though.

[Rich]

Are the Mux and DVR in the same room, do either have a loop through connection?

Im sure if they were you wouldn't use a T but just getting an idea of the circumstances, is the camera AC or DC.

[Alexg]

Rich,

Nah there not close to each other at all but both do have a loop through. It would be very dificult to get a coax to the first mux and loop through it to the DVR, but not imposible. Its frustrating as the the DVR at the other location is only tempoary, The camera was earlier today 24v AC but I've changed it to a new one and thats now on 12v DC, both cameras are giving the same problem.

[ian.cant]

You need to lose the T-piece, loop through from one or the other and terminate at the last device.

I would only ever use a T-piece as a last resort, avoid them as much as you would avoid a Rottweiler.

When your connected to either the mux or the dvr only does the problem go away?

Does the problem only appear when your connected to both?

I have a feeling this is an earthing problem, just a bit of a gut feeling.........

[Alexg]

Ian, Yes problem disapears when loosing the new DVR.

I guess I'm gonna be up in the loft tomorow getting this damn cable to the MUX...blah!

I can't see this being an earth problem as there all on one earth.

[breff]

I agree with Ian, it sounds like a ground loop problem.

[ian.cant]

I agree with Ian, it sounds like a ground loop problem.

But humbars would run up or down the picture.........

This sounds more like slight ghosting due to a termination problem. Till its connected correctly then its difficult to be sure.

[Doktor Jon]

From what's been described, it's very unlikely to be an earth loop problem - I agree that it's more likely to be a termination problem.

Alexg, if you can't manually switch the terminations on the multiplexer / DVR looping outputs, see if you can lay your hands on a couple of BNC 75 Ohm termination plugs, and fit a couple of those on the unused outputs - costs peanuts, and it's worth a try.

If you have any other cameras connected, you should also consider that any of those may be contributing to the problem; and don't forget to terminate any unused monitor outputs (but you've probably done that already!).

If you can fit a 2:1 VDA (away from the camera), that's possibly your best bet, but it's certainly not the cheapest!

Hope you get it sorted,

D.J.