Power supply fried 13 cameras???

[gb5102 0]

Hello Everyone,

 

First post here- found this site about a year ago and it has been a great source of information/opinion on multiple subjects; there is definitely a lot of very knowledgeable people hanging out here and I appreciate your generosity.

 

Brief intro- I am in the USA- Wisconsin to be exact, and I got into CCTV ~6 years ago working for an audio/video company that went under. After they collapsed, I thought that since CCTV and electronics in general are very interesting to me, and I knew that there are a lot of 'hack' companies around here, I thought I could do better on my own. I am mainly a one man operation, but have a couple of reliable people to help me out on bigger jobs. I try to set myself apart from the rest by always doing quality work(even if it means cleaning up someone else's mess) and standing behind it no matter what(within reason of course, some people are just crazy...) and this philosophy has worked out well for me- all my business is word of mouth and I have plenty to keep me busy.

 

Well, on to my question then- As the title states, I somehow lost 13 cameras on a system I was working on today, only 2 survived. I'm not exactly sure what happened, which I why I thought I should post, to see if any of the experts here can help me understand what went wrong....

 

Basically, I upgraded the old DVR with a new Geovision system, and re-used the existing(6-year old) Altronix ALTV1224DC2 which looked to be in good health(clean, no bulging capacitors etc). I checked the output, and it was running @ ~13.5V.

 

Existing cams were also reused, they were basic el-cheapo 12v black plastic domes(no brand or other markings of any kind), 7 were IR, 6 were non-ir. They definitely fried, you could smell the magic smoke. The 2 that survived were one(the only) existing Honeywell 12v fixed dome, and a new Everfocus dual-voltage IR dome that I installed.

 

The first thing I thought was that I somehow reversed the polarity, but I triple-checked everything and I am sure that was not the case. I initially gave a bit of thought to the voltage output being a bit higher on the altronix, but I never really gave it much thought since everything was running that way for the last 6 years or so, plus there was some longer runs of 18awg so I figured it was to compensate for voltage drop when the IR kicked on.

 

The only change to the power that I can think of is I relocated the altronix(same circuit) and in the process, removed a tangled mess of splices and extensions(~15feet of cat3 cross-connect wire) that were added to the cables coming from the cameras by the last installer. Do you think removing the extensions caused enough of a voltage gain to fry the cameras?(never checked the before and after voltages at the cams)

 

One thing odd that I did notice during my troubleshooting, was that I could feel a bit of voltage 'tingling' if I touched the metal altronix enclosure with the more sensitive skin on the underside of my arm. Like there was some type of 'stray' voltage. Not sure what to think of that. Another thing to note, is that the enclosure was never grounded, it had a 2-prong power cord.

 

So now, I have to try to explain what happened, and of course this is a big customer with lots of properties, so I will likely end up replacing them all on my dime just to keep them happy. Luckily they weren't $500 cameras, but then I'm thinking I would probably not be in this situation if that were the case...

 

So all in all, I'm not quite sure what to think, and its really bothering me not knowing what was the problem....Maybe someone here can help me to understand.

 

Sorry for the long post

-GB

[Campbell 0]

You didn't accidentally flip to 24VAC did you?

[gb5102 0]

Sorry for the delayed response, been crazy around here...

 

I'm positive I didn't flip it to 24V, but I'm pretty sure there is something majorly wrong with the electronics in the power supply.

 

Was doing some testing on it, and I noticed that it is putting out a spike sometimes when first powered up. Randomly, maybe every 5-10 times turning it on, my dmm is reading a brief(maybe 500ms) spike of ~100V AC between the '+' and '-' outputs. Also, anytime it is powered on(with no load), there is ~170mA @ ~60VAC between the '-' output and earth ground. So I'm guessing that some component in the switching power supply failed...and the cheap 12v cams went with it.

 

Has anyone else run into a situation like this, or is it just my luck?

[Birdman Adam 0]

Well I'd say you just got really unlucky.

 

It is certainly possible for the supply to fail, maybe with higher mains voltage leaking through to the low-volt side. You say you can feel a tingling when touching the metal case? Take a multimeter set to measure mains voltage, and test between the case and the ground hole in an outlet (the round one at the bottom).

 

It should read 0V, if there is a significant voltage, something is definitely wrong with it, I would throw it out because it is a fire hazard and a shock hazard. Imagine if your hands were wet, and you touched another *properly* grounding case at the same time (and there is no GFCI on the circuit)!!!

[gb5102 0]

I forgot to mention that, i did test between the power supply chassis and earth ground, and I ended up with about 55VAC. The current was about 40mA.

 

So yeah i agree, i got really unlucky. Would have expected something like this from the generic no-name 12v supplies that I come across quite frequently. Those are the ones that have scared me up until this point, most are not even UL or FCC approved, but the worst I've seen from the no-names(so far...) is picture quality issues from the noisy output.

 

At least altronix has a lifetime warranty, we'll see how that goes, but I don't think I would trust this model anymore personally...

[lupy 0]

there is something to be said for an in line fuse in these systems. It might not have saved you here, but a lot of low voltage wires are not very stong and a dead short can cause the supply or wires to overheat.

[jack in oz 0]

Hi GB,

I'm sorry to hear about your cameras being fried. I'm in the process of building a residential CCTV system of my own and I've decided there's no way I'll be using a switchmode power supply. I just don't trust 'em and your sad story has added to my distrust. The good old linear power supplies seem to be quite a bit more expensive, but compared to replacing most of your cameras, I guess they are cheap. All the best.

Jack.

[gb5102 0]

Jack- I agree with you 100% on distrust for the switchers- too much that can go wrong. When I need 12vdc I like the MG Electronics DPS-12DC-16UL- uses good ol' transformers and its individually regulated.

 

This is one reason I prefer 24v AC systems- the main power supply is essentially a simple step-down transformer, and although there is a few more parts inside the camera there is less chance of a single component taking out the whole system...plus less worry about voltage drop with higher-powered cams(IR/heaters).

 

At least the cameras that got fried here were the '$25 specials'- client had no problem paying the difference to upgrade them to better 24vac cams.

[jack in oz 0]

GB,

 

I agree about the simplicity of 24VAC power supplies. I'll be using 24VAC for the cameras that will take it and adding a 12VDC regulator to power the cameras that won't take the 24VAC. All of the used Big Brand (Samsung, Pana, Bosch, etc) cameras I see on EBay seem to accept 24VAC anyway.

 

Jack

[hardwired 0]

Jack- I agree with you 100% on distrust for the switchers- too much that can go wrong. When I need 12vdc I like the MG Electronics DPS-12DC-16UL- uses good ol' transformers and its individually regulated.

 

This is one reason I prefer 24v AC systems- the main power supply is essentially a simple step-down transformer, and although there is a few more parts inside the camera there is less chance of a single component taking out the whole system...plus less worry about voltage drop with higher-powered cams(IR/heaters).

 

At least the cameras that got fried here were the '$25 specials'- client had no problem paying the difference to upgrade them to better 24vac cams.

Another consideration is that 24VAC cameras are usually much more immune to ground loop issues.

[Numb-nuts 1]

Another consideration is that 24VAC cameras are usually much more immune to ground loop issues.

 

That's interesting, is there an explanation for that?

[hardwired 0]

Another consideration is that 24VAC cameras are usually much more immune to ground loop issues.

 

That's interesting, is there an explanation for that?

I think it's mostly that the input power doesn't share a ground reference with the video output cable shield, compared to 12VDC cameras, where the power ground and the video ground are usually tied together internally.

[gb5102 0]

Like hardwired said, on 12vdc cameras(at least most cheapos) the video shield is generally tied to the negative power wire- creating an attractive secondary path for current to flow. Creates 2 paths to ground- 1 thru power wire, 1 thru video wire=ground loop

[hardwired 0]

Like hardwired said, on 12vdc cameras(at least most cheapos) the video shield is generally tied to the negative power wire- creating an attractive secondary path for current to flow. Creates 2 paths to ground- 1 thru power wire, 1 thru video wire=ground loop

On a few jobs we've inherited with 12VDC cameras, I've still had to leave a bunch of individual wall warts for each camera- attempting to put them all on one supply created ground loops on several cameras. Ground loop isolators could have helped, but do you really want to use a hundred dollar isolator on a fifty dollar camera?

[Bunited2 0]

I understand the part about wanting/keeping that impression with

the customer and especially would not want him/them to think at

all about being incompetent, but you did say the PS was existing

in the system.

 

Powered stuff can be very funny things it could work great for years,

but power that thing down once and back up again and who knows

what can happen.

 

If you can get the factory to confirm the power supply bit the dust

due to use and not error on your part, I would definitely approach

the customer to handle the cost of camera replacement. After all

it was/is their component.

 

Just because you relocated it, should not make it your responsibility

for it's malfunction and hence removing the cameras from the face

of this earth.

 

Good Luck

 

Bunited2