Camera Video Signal Cutting In And Out - Any Ideas?

I have an analog license plate camera KT&C, KPC-LP850NH which has been giving me problems for some time now. I installed it last November on an exterior wall of our building. This is in southern California where it doesn't get too hot or cold. The power supply is a 12V ~2A and connected to an outlet right next to the camera's location on the inside of the wall. It is connected to a Vivotek VS8401 encoder which is connected to a Windows 7 computer running ExacqVision. Up until a couple of months ago, the camera was working flawlessly. Lately, however the video signal is cutting in and out intermittently. At first, the picture would flicker a little during the morning at around 10am-11am and then restore itself. This would also happen late at night, around midnight. Then I started getting "Video Loss" and a blue screen on that channel. That typically happened at the same times and would eventually restore itself. The amount of time the channel was down kept increasing until it could be down most of the day.

I've tried a few things to figure out what the problem is. When I first started having the problem, disconnecting the power supply and reconnecting would make the problem go away for a bit. If I left it unpowered for a whole day, the problem went away for a longer time, maybe a few days. I hooked up an outlet timer to shut it off each day for thirty minutes at a time of day when some overlapping cameras are able to reliably pick up plates, but eventually cutting the power didn't seem to be effective. I had a ground loop isolator attached, which I removed because it seemed to have caused a problem with another camera previously. I thought that had fixed the problem at first, but it came back. I switched from using a coaxial cable (about 150 ft worth or so) to a CAT5 with these video baluns which I used with about 15 other cameras without a problem. I still have the issue. At first, if I disconnected the video cable at the camera and then reconnected it, the problem would clear up for a bit. Now that doesn't seem to work, but if I disconnect the video cable at the encoder and reconnect, the problem goes away immediately.

Vivotek recommended I tried moving the camera to a different channel on the encoder to see if there was a hardware problem. I did that yesterday, and within twelve hours or so, the camera started having problems on the new channel, while the camera I moved to the LPC's old channel had no problems.

This is starting to drive me nuts. The camera is great- I've got it tuned in to pick up almost every plate on vehicles going up and down the main approach to our building- but I've got to get this figured out. Has anyone had a problem like this or have any ideas? Thanks in advance.


"I did that yesterday, and within twelve hours or so, the camera started having problems on the new channel"

Now you know it's not the recorder but either the camera or power supply. I would bet money on the power supply first. Probably a laptop style?

We had the same issue with an anolog camera, encoder to NVR setup and we replaced, encoders, camera until our tech noticed the led flickering on the ps

It will probably be a "brown out" from your electric service provider. When they have large loads the voltage can drop to less than 110vac. When that happens, analogue cameras continue to operate, IP cameras fail to produce a usable image file. Is there something at your facility that turns off or on during that time frame? It could be this camera because it has a longer power wire than your other cameras. It can be "Radio Frequency" RF noise created by floresent light issues. I would look for power issues.

By any chance would the outlet you have it connected to be on an emergency circuit?

Just to rule this out: does the 'cut-out' coincide with the IR LEDs coming on?

Based on your own troubleshooting, the problem seems to be either in the power supply or the camera.

Now that doesn't seem to work, but if I disconnect the video cable at the encoder and reconnect, the problem goes away immediately.

You should keep a ground loop isolator installed regardless, because EMI can change over time. It's a good step to find one that you can count on and install it.

Do you have a multimeter? Can you check the voltage/resistance coming from the camera? I'd be glad to give you a few tips on how to get good readings if you're a little sketchy on that part.

for some reason, the vivotek encoder is losing its sync from the camera.

Agree with Brian, 90% of the time, when analog camera loses sync, it is the power and ground loop isolator is always recommended.

Check the power output of the 12VDC and see if there is anything that will cause the wall power source to have a power dip which coincide with the drop off, like Air Conditioner, pool pump/motor, etc. Cabling could be an issue, check for EMI sources, like CFL light, neon sign transformer, big motors, etc.

Glenn, by the way, excellent description of the issue. It helps a lot!

You guys are great. Thanks for the quick replies.

Now you know it's not the recorder but either the camera or power supply. I would bet money on the power supply first. Probably a laptop style?

This is the power supply, similar to a laptop. I could get another and swap them out. I just don't understand how it would be the power supply if just disconnecting and reconnecting the video cable at the encoder makes the problem go away.

By any chance would the outlet you have it connected to be on an emergency circuit?

No, it's not on an emergency circuit.

You should keep a ground loop isolator installed regardless, because EMI can change over time. It's a good step to find one that you can count on and install it.

Do you have a link to one you recommend?

Do you have a multimeter? Can you check the voltage/resistance coming from the camera? I'd be glad to give you a few tips on how to get good readings if you're a little sketchy on that part.

I do have a multimeter, and I know how to check the voltage from the power supply. How do I check the voltage/resistance from the camera?

By the way, when I started this thread, I had disconnected/reconnected the video, and the camera was working fine. Now it is back to video loss.

Thanks again for the replies.

Just to rule this out: does the 'cut-out' coincide with the IR LEDs coming on?

Forgot to respond to this one- no, it doesn't seem to coincide with the IR LEDs coming on. This tends to happen most often in around 10am, long before the IR comes on, and then late at night, hours after the IR comes on.

Check the power output of the 12VDC and see if there is anything that will cause the wall power source to have a power dip which coincide with the drop off, like Air Conditioner, pool pump/motor, etc. Cabling could be an issue, check for EMI sources, like CFL light, neon sign transformer, big motors, etc.

There isn't anything else major on that circuit that would be turning on or off at these times that I can think of. There is a separate high-power IR illuminator (12v 3A IIRC) plugged into the other outlet on the receptacle, and some other cameras on the circuit (which have no problems).

"I just don't understand how it would be the power supply if just disconnecting and reconnecting the video cable at the encoder makes the problem go away."

Analog cameras output composite video (sync and video) that an analog CCTV monitor (anybody remember those things) can handle better than a DVR input when the sync gets low from say a defective power source or poor grade, too long a run coax. So disconnecting the video cable and reconnecting it allows the DVR to sync back up (for a while)

I think your camera can do 24 vac so try a transformer/power supply or a higher grade DC supply

Do you have a link to (ground loop isolation/protection) one you recommend?

I have firsthand experience with GEM's GLI-BNCPJPT-1. They cost ~$20/ each, but you might find them cheaper buying through a distributor.


IMPORTANT: These install at the 'End of Line' at the camera end.

I do have a multimeter, and I know how to check the voltage from the power supply. How do I check the voltage/resistance from the camera?

One other question that I should have asked before: does your multimeter measure 'peak to peak', 'RMS' or 'not sure'?

If unsure, can you post the model, and we'll check?

We need to measure P-to-P voltage, and if we can't have an issue. I forget that not all meters have this feature!

Watch this short clip:

(See our post on the Bytebrothers LVPro for more details on the unit being demonstrated.)

As you can see, VPP is an important indicator of 'camera health', including the one you're troubleshooting:

This string brings back memories!

I find myself nodding along to most of the comments so far....

Only comment I have is, when troubleshooting, to never ignore a component based on logic... i.e. possible power supply issue; discounting the power supply because it doesn't make 'logical' sense since you disconnect video cable and it (temporarily) solves the problem.

The problem with logic is that it's based on what we 'know' - not what we don't know (or just have never seen before). :)

Brian- I can't answer your question, so hopefully you can tell from this picture. Thanks for the ground loop isolator suggestion- I ordered one from Amazon. I am going to take a look at the video after this post. I also ordered a new power supply to test. Thanks for the explanation on how that could be the problem, Mark.

Power supplies do fail. They can also read the correct voltage with hardly any amperage output. I'm betting on the wall wart being bad.

You can also try a higher amperage same voltage transformer. The camera will only pull the amperage it needs.

Your camera's spec states it draws 1.6 amps max at 12 volts DC. You need at least a 2 amp. It does not take 24 volts A/C so don't connect an A/C transformer to it.

I saw you tried the switching of cameras on the encoder have you tried a known good camera swap leaving power supplies at the camera? This will tell you if the problem follows the power supply or the camera.

One more thing, the resistance termination should be 75 Ohms. Maybe your encoder or DVR has a termination setting or physical termination balun or switch set wrong. I have seen intermittent video because of a resistance termination problem.

You can also try a higher amperage same voltage transformer. The camera will only pull the amperage it needs.

That's what I was thinking. I ordered one of these off Amazon yesterday and got it this morning. I swapped power supplies about twenty minutes ago. It works right now. We'll see if it has any issues over the next few days. If so, this was an easy fix and I'll remember to just try a new power suply next time I have an issue like this. I'll look into your idea about resistance if the power supply doesn't pan out.

Hi Glenn,

Have you tested the voltage of your power supply with load? I usually use a DC connector that splits into to cables with DC connector at each end. That way, you can use the extra connector with your tester probes. If the reading shows a more than 10% voltage drop, than you can expect problems especially if the voltage drop is much higher.

Hello Ronald,

I have not tested the voltage. So far I just tried switching out the power supply. I tried two other power supplies, one 12v 4a and one 12v 2a (the original power supply is 12v 2a). The camera still had intermittent problems over the couple of days that I tried each adapter. I just installed the ground loop isolator that Brian recommended, so I'll see if that helps and then try some more of the suggestions in this thread if the problem persists.

Glenn,

Sounds like a loose connection or moisture in contacts either within the camera or leading to the camera. Do you use dielectric grease? I had a client in which I had to open the wall in order to fix perfectly twisted wires (as junction) in which moisture had killed the contacts. Soldered wire junctions would have prevented that. B connectors with dielectric grease are very good too.

Glenn,

Have you tried to connect the camera to the normal analog cctv monitor and look if the problem still exist?

Two things to try that will 100% isolate it to the camera.

1) Use a "Alarm Control" Type 12VDC power supply. Basically a 12VDC Battery with trickle charger so you ALWAYS know you have 12VDC to the camera even if the 120V drops or quits. Get a battery that will give you enough amp hours so it can run an hours or more.

2) Connect the Video Out directly to a DVR so you record video all the time.

Now you hav isolated it to the camera .

Thanks for all of the advice. Sorry I haven't responded for awhile, but other matters took priority over getting this fixed. I installed the ground loop isolator Brian suggested. The problem continued. I attached a Y connector to the power adapter so that I could check the voltage coming off the power supply. When the camera is working, the voltage is at 12.4V. When the encoder shows "Video Loss", the voltage is still 12.4V. I have tried three different power adapters (although I only tested the voltage on this latest one), and the problem persisted with each, so I don't think that is the problem. I've tried connecting the camera with Cat5e cable with video baluns as well as with a long run of BNC cable (both times the power supply is local). The cat5e and BNC cables are routed very differently, so for the most part they are not close to each other, i.e. it is unlikely they are both running past something that is causing interference, unless it is in the server room where they meet at the encoder. However, there are many Cat5e and BNC cables meeting at the same place, and I only have issues with this one camera.

Regarding possible moisture in the contacts- This is a bullet camera, so the enclosure is sealed, and I have never opened it. The video and power cables pass through a hole in the concrete wall which is covered by the camera mount. The mount has a rubber gasket between it and the building. All of the connections are inside, and no moisture is apparent when I disconnect and reconnect them, so I don't think that is the case. I suppose it's possible that the camera is not perfectly sealed and that some moisture entered, but this is southern California- we barely get any rain and the humidity is pretty low, so I don't think it's too likely. I'll have another look at the exterior of the camera with this in mind.

I just ordered the Low Voltage Pro level 3 that Brian mentioned, and I'll update when I have some results. Thanks again for all of the suggestions.

I went and looked at the camera again, and it doesn't look like there is anythere moisture could be getting into the housing. However, I did notice that a sticker on the back of the camera says 24VAC, although the instruction manual only specified 12V DC. I hooked up a 24VAC 40VA power supply, and we'll see if that makes a difference. I don't know why it would as I was getting 12.4V before, but hopefully this fixes it.

Glenn, one uses 24 VAC mostly on long wire runs so as to avoid voltage drop due to long distance, otherwise regulated 12 VDC is the safer way to go, I think.

Have you checked for flaky wires? Often times when skinning wires the skinning tool would cut too deep and because it is at the edge of the wire sleeve it is not detected by naked eyes. This happens mostly with small wires with tiny copper core.

When the camera goes off line, can you see if the camera is still on (LED's on at night)?

Have you tried using a stand-alone monitor at the BNC connector on the DVR for that camera? Have you checked the BNC connector itself? If using twist-on BNC connectors, expect trouble as they tend to fail over time. Pressure-fit ones are much better, especially those that are 100% metal, no plastic washer.

I tested this camera many different ways. To quickly summarize- The peak to peak voltage of was around 1.4. When the encoder was showing video loss for this camera, I plugged in my handheld portable monitor to the secondary video connection on the camera, and the picture was fine on that monitor. So it didn't seem to be a power issue. I switched out to another analog license plate camera, and that camera did not have this issue for the three days it was up, so it doesn't seem to be a problem with the encoder, power, or cat5e cable. I think there is an issue with the camera itself. I sent an email to KT&C tech support which was not answered.

I ended up replacing this camera with a Stardot Netcam SC. I run it at 1080p and get excellent picture and license plate recognition over a much wider area during the day. At night I get useable images from the most important directions at least, and with some higher powered IR illuminators I think the night performance will be excellent as well. I bought a few more to replace some other analog license plate cameras, and I have to say that they are great cameras.

Thanks for the followup, Glenn.

Sometimes, you just have to call the baby ugly. (and sometimes 'the baby' is a $900 camera.)

I ended up replacing this camera with a Stardot Netcam SC. I run it at 1080p and get excellent picture and license plate recognition over a much wider area during the day. At night I get useable images from the most important directions at least, and with some higher powered IR illuminators I think the night performance will be excellent as well. I bought a few more to replace some other analog license plate cameras, and I have to say that they are great cameras.

Ugly! Just because of the time involved to troubleshoot.

Glenn,

That is why I always carried a spare AD Ultrdome and PC board, Pelco Spectra, Some box cameras with and without auto iris lenses of both breeds 12 VDC and 24 VAC.

If basic troubleshooting doesn't work replace with a KNOWN GOOD and follow the problem.

Yes Brian, this was indeed an ugly baby. Too bad KT&C didn't offer any support.

Scott, that's a good idea. I always have some extra cameras around, but I was reluctant to switch it out because it took me a lonnnng time to get the KT&C adjusted. I had it set up so it perfectly captured every undamaged, unobscured plate, day or night, coming or going on either side of a fairly wide 2-lane road as well as pulling in or out of the road that turns behind our building, and it was perfect for many months.

However, installing the Stardot camera was far less adjustment, and the only thing I am working on now is getting a little better IR illumination on the plates to ensure they are clear at night because that isn't perfect yet. I am covering a much larger area and getting great pictures of the vehicles as well, at least during the day, so in the long run it's probably not a bad thing that I had problems with the KT&C.