CCTV Video issues

I have seen things powered from 12VDC not work when the fine print said

24VAC on the cameras. Another sad problem may be that the power supply you are using has self restoring circuit breakers. A good idea in some applications, but not on cameras. The circuit breakers trip too slowly and a camera can be damaged before the circuit blows. Only use fused outputs on camera jobs, unless you don't mind replacing damaged cameras. They are more expensive than fuses however. Another problem might be a grounded wire. It can pick up some building A/C and give the uglies to the video. There are several ways to check it, even if you don't know how to check for grounds and inductances. Try viewing a single camera via a monitor that is not connected to the DVR. Get a good picture established leg by leg until you find the guilty dog.

We have such a device. It is expensive. I think in the $700 to $1000 range if I remember right. We keep it in its own briefcase sized case for protection. I only use it when factory tech support needs to be convinced they have a problem and not me. It measures very specific items from the camera. You could even focus a camera with it without even seeing the actual video image once you get used to using it. If you're using 12VDC cameras it sounds like you're fishing in the low end of the price market. It is hard to justify that kind of expense in that market segment. I would call around to a few pawn shops or try eBay and see if you get lucky. What you are looking for is something like this: A Camera Master I or Camera Master II

ARE IRE UNITS ?IRE Units are used worldwide to measure video signal amplitude instead of Volts Peak-to-Peak. This system of measurement is much easier to use than Volts Peak to Peak and can be directly measured on the CM-1 hand-held, battery-operated Camera Master instead of a bulky Wave Form Monitor that requires 120 VAC power. The following table defines the amplitude of various parts of a video signal. In terms of IRE Units and Volts.

MEASUREMENT I.R.E. UNITS VOLTS Sync Pulse 40 0.285714---- Color Burst (p-p) 40 0.285714---- B/W Picture 100 0.714285---- Color Picture 120 0.857142---- B/W Composite (p-p) 140 1.000000---- Color Composite (p-p) 160 1.142857----

I hope this helps.

sounds like one of the cameras is pulling down the others power them up one at a time till condition apears then you either have to much power draw or bad camera

This may seem excessively simple, and is one of those things you'll think you couldn't possibly have screwed up, and then end up smacking yourself in the head... but check that the 'polarity' matches on the baluns on those distorted cameras. I'm not sure why, but it DOES matter with the baluns (the passive ones, at least, I haven't used actives yet).

Checking the power is a good idea too - first thing to check is to measure the voltage at the cameras, make sure it's not dropping too much. A quick test with a 24VAC wall wart will tell a lot (assuming the cameras support 24VAC) - I've run into issues before where "dual-voltage" cameras wouldn't work for love or money on a 12V supply.

30 feet is well below what i have done 120 feet. most cams signal is abt 1vp-p, and input sensitivity at dvr or input on receivers usually is good for sigs down to 100 mv or so.

distortion ((wavy side skew?) may mean the sync component of the video signals is getting bad matched or even flipped during one of the balun connections.

bad distortion usually means the reciver cannot find a comon sync to use. frame rolling is als an indication.

as an aside, are the cams all same , ntsc or pal?

Doug:

I agree that this could well be a power issue. My confusion comes from the distortions showing on both the closest and the furthest indoor

12VDC domes. The closest shows no power drop while the furthest shows a drop to 11.5VDC.

Roland:

I wasn't aware that breaker protected power sources were available. We've always used fuse-protected power supplies. That same in this case. I will take your advice on the camera-by-camera viewing to check for ground faults though, it's something I'd forgotten about. As far as the CM1 & CM2, I'll let my boss decide, it's his money. ;)

Nick:

We did the voltage calculations before we started and although we are close to the 4 amp capacity of the power supply, we aren't going over. Besides, the distortion is only seen when viewed from the DVR, not at the camera itself. If it were a power issue, wouldn't it be evident on both ends?

Matt:

I will double check the baluns as per your suggestion, but I'm pretty sure we go them straight. Solid color to +, striped to -. The only dual voltage cameras we have on the system are the "box cameras" (Panasonic, lens sold seperately, gotta put it in an outdoor enclosure) and they are working wonderfully and presenting the best pictures. One is even further out than the furthest dome (which is the one that looks the worst).

haptictz:

You seems to know a thing or two I don't. For instance, what is voltage peak-to-peak, how do you measure it, and what kind of readings am I looking for to indicate good, bad, or otherwise? And for your last question, no. Fully half of the domes are mini-domes that can't be that expensive while the others are fancier tamper-proof kind with varifocal lenses and fully articulating inner mountings.. (very nice, probably $200 a piece) Would mis-matching NTSC and PAL generate this kind of effect?

Thank you all for you input and look forward to hearing more suggestions. I won't be tackling this project again until next week, but I'll be sure to let you know how it goes.