18 channel cctv power supply box question(s)

[Radman171 0]

Hi all,

Ran into a weird situation the other day. I've got a home surveillance system which I installed some years ago (and which I am constantly "tweaking"!). We had a power outage the other day and when power was restored, the 18 ch. power supply box was only putting out about 5 to 6vdc for each camera instead of 12vdc. Had to quick order a replacement box to get everything back online.

 

Our whole house is on a primary surge suppressor, and the cctv outlet is on both a surge suppressor AND a UPS. Despite all this, I still lost the power box.

 

I could find absolutely nothing online about how to troubleshoot any of these power supply boxes, or any schematics either. It would appear that something simple is amiss on the power box's circuits, so I would like to repair it for future use.

 

Any suggestions? Any feedback would be greatly appreciated! Thanks.....

[Billy_ICU 0]

A UPS will pass through power company electricity while power is on, but generate it own power when the power is out...

 

But what is called an "Online UPS" will always generate its own electricity. Also a "true sine" UPS will create the best electricity. So best would be a true sine online UPS. Although a voltage surge could still fry the UPS.

 

I have a surge protector for the whole house in the main electric panel as well as outlet or power strip surge protectors at each location where something electronic is plugged in (everywhere). Not had anything fried in 15 years.

 

As for your power supply... Many times voltage regulators will go out. Sometimes diodes or bridge rectifiers.

 

I would check the AC voltage after the transformer, then the DC voltage after the bridge rectifier. Then the voltage after the voltage regulator.

 

P.S. Of course always first check main AC power and fuses!

[Radman171 0]

Thanks billy, I will try your suggestion!

[the toss 0]

Those multiway power boxes are (generally) based on a computer style switchmode power supply with either fuses or PTC protection. The most likely cause of failure will be the caps. Look for the expansion joint on the top of the caps.

[Radman171 0]

Well, this is weird! I had checked the box a few times over a couple of days but it was always the same -- low power output. When I sat down at the bench to test your suggestions, the box powered up just like normal at 12vdc. ??????

 

It does have the PTC fuses, but how long does it take for those to reset themselves? In this case, it was about 5 days. I thought they reset a lot faster than that....

[Billy_ICU 0]

Electronic things "know" when you are watching! They will behave perfectly when you pull out the multimeter. Then misbehave again as soon as you are no longer looking!

[mgb 0]

Just to be clear. When you first took your voltage measurement and measured 6 VDC, were the cameras still connected to the power box.

And when you just measured again and got 12vdc, were they not connected?

[Radman171 0]

When I was first trying to figure out what was wrong, I checked the camera power outputs with the meter while the cameras were still connected -- and got the 6vdc reading. I then disconnected all the cameras, pulled the box from where it was mounted, put it on the bench and checked the outputs again. Still 6vdc. That's when I submitted the post asking for help.

 

Then, of course, when I went to actually try billy's suggestion to troubleshoot it, the thing was working fine again.

 

In the meantime I had already ordered a new power supply box, since I had to get my system up and running again ASAP.

 

At this point my position on this whole situation is going to be, "You can never have enough CCTV power supply boxes, right?"