Camera - Power Supply Problem

[jcjc77 0]

I have 2 altronic altv244 24vac supplies. I have 4 speco 7705-dnv cameras attached to each supply. This system was installed several years ago, however I have no knowledge of when they failed or what service was done to them. I don't have much background in cctv, but I have to determine if these cameras are defective.

 

I get no image, just noise on the monitor from all cameras. These are IR cameras. In near complete darkness I can see red from the led's of only one camera. The rest are dark.

 

The 24ac supply reads 27.6vac to 27.7vac at the cameras. This seems high since the cameras are 24vac cameras. The supplies are 24 vac supplies.

 

Is 27.7vac enough to burn out the cameras or are they protected from overvoltage? Is it normal to have a 24vac supply output this high? These supplies can not switched to 28vac, so I know they are 24vac supplies.

 

Your help greatly appreciated

Thanks

[cwd10 0]

I think on most of these type of power supplies, the voltage runs a bit high until there is a significant load put on them. In other words, the voltage should be about what you measured with little or no load, and should be pulled down to around 24 volts with a full load. I seriously doubt that any camera would burn out with that little bit of extra voltage. From what you describe, it seems that most or all of the cameras are DOA. If the cameras were functioning properly, they would be putting more of a load on the power supplies and therefore pulling the voltage down more. I suggest unhooking them and testing each one individually. Make sure to hook them up directly to a known good monitor, and try using a different power supply if possible, just to be sure. Just use the good old process of elimination.

[cachecreekcctv 0]

Agree with above statements. Remember one thing, your output voltage is directly related to your input voltage on any transformer. All transformers have a specific amount of of Primary and Secondary windings. If you input 110vac you might get 24.5vac on the output. On the other hand, if you input 117vac, you will get a slightly higher voltage on the output. Just the way they work. I seriously doubt that your 24vac cameras were damaged by 27vac. Again, when you are measuring voltage, is it "free", or under a "load"?

[jcjc77 0]

Thanks for your input. From what I have read, it doesn't sound like the supply. I have tested two and they are DOA. Hope the others fair better.

 

BTW These two system do have any surge or spike protection and no ups. We have lots brown outs and power failures, so I thought this might be the cause. Once I get it up and running I want to add some protection. Is there anything you would recommend.

[cachecreekcctv 0]

I normally use either an APC or Tripplite. UPS with automatic voltage regulation is definitely the best. Keeps the outgoing voltage at a sustained level. Can get them from Tigerdirect.com or your local Circuit City, etc.