poor_red_neck 0 Posted January 11, 2015 This is a Zmodo ZMD-DD-SBN8 analog system. So I have 2 channels ran over a single CAT5 cable using Baluns on each side. Only about a 100ft run on the furthest camera, 60 on the other one. I have vertical "bars" of varying brightness that slowly go across each channel. Right to left on one channel, Left to right on the other. The bars disappear if I unplug one of the 2 channels' power. Unplugging other channels does not affect it. These are the cameras that come with the ZMD-DD-SBN8, as well as the power supply that came with it. I have tried other 12V power supplies, including a high quality 10A 12V power supply with very low noise. No change. It is currently night time and I just got done with the installation inside the house, so IR is on. I have yet to see if it does this during the day as well. My wiring is as follows on the CAT5 cable (CAT5e): Blue/Blue&White - Video for channel 2 Green/Green&White - Power for channel 2 Brown/Brown&White - Video for channel 3 Orange/Orange&White - Power for channel 3 I have tried adding a ferrite ring to one of the channels' power supply wires. Did not make a difference. I have a bag full of ferrite rings somewhere but can't find them, was going to add one to the other channel to see if that helps. It seems the negative of the power supply wires is tied into the ground of the video signal, as with my experimenting I noticed that if I unplugged one of the channels' power cable, and connected only the positive side it would still power the camera. I was considering using a separate power supply for just channel 3 but was worried about tying the grounds together like that if it would affect it. Any ideas? Share this post Link to post Share on other sites
poor_red_neck 0 Posted January 11, 2015 Did some more research. Seems to be a ground loop issue. I dug around my parts bin and just started experimenting. Added a 47uf electrolytic capacitor in line with the negative side of the balun at the DVR on channel 3. Vertical lines are gone! There's still a little tiny bit on channel 2. Tried adding another capacitor on channel 2 but it resulted in a loss of signal so I'll live with it. I'm sure a smaller value ceramic cap would probably work better, but its what I have and it worked. Just thought I'd post this so if somebody else searches this issue they can try this. I used a small crimp that you'd typically use for telephone wire so I didn't have to do any soldering or anything. So far it's working great! Share this post Link to post Share on other sites
jeromephone 6 Posted January 11, 2015 why not run 2 separate cables then if you ever want to switch to IP you can Share this post Link to post Share on other sites
tomcctv 190 Posted January 11, 2015 Also your other cameras not on car5 are on 100ohm cable Cheap cable kit Share this post Link to post Share on other sites
poor_red_neck 0 Posted January 12, 2015 I ran one cable for ease of installation. Didn't anticipate issues. I don't plan on upgrading for atleast 3 years. I'll battle that road when I get to it. These cameras draw less than 300ma, and there isn't that much voltage drop over the wire. Less than .4V at the load (camera) on the furthest camera, still good for 12.1V with the camera running in IR mode. You should see the wire that comes with the 60ft runs in the kit. It's got to be 32 gauge or maybe 30. If it works with the stock cables, CAT5 is plenty. I'm sure if you were running very long lengths that it would be a larger issue, but at only 100ft it's not an issue. Yes I know I'm using the included cables for two of the channels. They work fine, and I tried a short RG59 cable I had laying around and noticed no improvement in quality so why not use what was included. Prevents me from having to order additional cables. Share this post Link to post Share on other sites
tomcctv 190 Posted January 12, 2015 Reason is ...... Your on forum asking why lines on image Cameras dvr are 75ohm ..... So being on 100 will give you problems Cheap cable kits use same nutral for powe and camera .... Which would also give you your problem. Share this post Link to post Share on other sites
jeromephone 6 Posted January 12, 2015 Tomcctv is right on. the other thing to remember is that a cat 5 cable the different pairs are different lengths based on the twist of the cable. I don't know if that makes a difference but bottem line if you have a ground loop which it looks like you do you have to change something. You can try a ground loop isolater if you can determine the camera or pair that is causing the problem. They are pretty cheap but probably about the same as putting in the proper cabling. Share this post Link to post Share on other sites
