Extremely loud, sharp crack!

Hi janusz,

I would tend to believe you might have had a high voltage break down in you monitor. If it were full of dust in the area of the high voltage cable/capacitors you can get something such as you describe. Also a bit of ozone in the air that can be smelled. You can get a thin film of dirt that has built up that is very hard to clean that will conduct high voltage. IF THIS BE THE CASE DO NOT GO INTO YOUR MONITOR unless you know how to ground out the components. A visual inspection is OK though. You should see or smell something.

A grounding rod is the normal tool for this job by the way. Hope this helps.

Unless you are a trained technician, I'd steer clear of opening up the monitor....and the LAST thing you should do is use a static strap while working in a monitor. That's asking for real trouble. A monitor will kill you (even when unplugged)....not just hurt. Just do the sniff test.

I have seen a MOV blowup first hand. Big bang, bright flash, lots of smoke. Technician awkwardly walking towards bathroom. If it blew and you were there you should smell it unless it's enclosed in something with no vents. Most of todays surge protectors have an indicator light that will go out if the protection circuit (MOV) isn't working any more. The good ones have a 20 or 30 amp fuse (whatever the MOV is rated for) in series with the MOV. A short duration spike wont blow the fuse, but a big surge will blow the fuse, open the circuit and put out the light. What was the humidity like in the room. High humidity can case a flash-over either in the monitors flyback transformer or in the PC's power supply. PC power supplies are switching power supplies and have high voltage circuits inside. I have seen a PC power supply ark over, it didn't work after ward. If you leave the Monitor unplugged for several hours (overnight) the high voltage will bleed off. All of the high voltage leads are insulated and unless you start unplugging things inside you should be safe. Usually when you get a high voltage flash-over it leaves a carbon trail across the surface. After that it just flashes over every time you try to generate the high voltage. Basically if it happened once the odds get better for it to happen again, unless it's arcing threw air. That's where humidity comes in. I'm thinking a capacitor blew or an MOV blew up. The surprising thing is that everything is still working, I would have expected something to not be working anymore. Have a good look at your UPS to make sure it is still working, unplug the AC and see if it still supplies the load.

No flash. No smoke. No smell. I was sitting about 5 feet away. I got up and looked around the monitor and case within a few seconds of the "crack" and did not see or smell anything. I was expecting to see flames -- and was ready to reach for the fire extinguisher in the room. :-)

If I had not see the monitor going through the reboot cycle I would have thought it was something besides the machine. It may be just a coincidence but this happened about 2 hours after I made adjustments to the monitor using Samsungs utility, Natural Color. Oh, I have two printers nearby but they were disconnected and they work just fine.

Afterwards, there is absolutely nothing to indicate there was ever a problem -- everything works! I ran the system about 6 hours today and there was no hint of any kind of problem.

The green light (says "Protected") on the surge protector-switch panel is on. UPS is in good working order. Unplugged it and it assumed power while sounding an alarm.

I have sent a brief description to the Samsung Service department. The monitor has a 3-year warranty. I don't like the idea of opening up the monitor; I am not a service tech and not the least bit qualified. Someone mentioned earlier about not using an ESD strap! I do know the difference between static discharges and high-voltage discharges. ESD straps could cause death; they are not for high-voltage grounding. In any case, I've asked the manufacturer to advise on the course of action.

If I ever learn the cause, I will post back.

Thanks all,

janusz

You are probably better off not opening the monitor, especially if your nervous doing it. I'm a tech so I have no problem doing it. What I mentioned above would be a safe way to just take the cover off and have a look inside for obvious damage. While it could be the monitor, I think it's more likely the PC power supply. My reason is that you saw the PC reboot. I don't think a monitor problem would cause the PC to reboot, but stranger things have happened. Since everything is still working you'll have to just wait and see if it happens again.
I don't think the monitor software could cause the monitor to fail. Normally you won't have problems with the monitor unless you set the refresh frequency on the video card too high, too a frequency not supported by your monitor. On older monitors the screen would go nuts and you would hear a high pitched squeal. In a very short time you could damage the monitor. Todays monitors are protected from that and just give you and "out of range error" on the screen.
Problems like this are a techs worst nightmare. You know something failed, you don't know what it was, and you know it will likely happen again.

WHATEVER YOU DO DO NOT OPEN THE MONITOR.. ITS DANGEROUS AND ELECTRICITY STAYS THERE FOR WEEKS ETC... AND YOU CANNOT REPAIR IT

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Originally posted by steppenwolf
WHATEVER YOU DO DO NOT OPEN THE MONITOR.. ITS DANGEROUS AND ELECTRICITY STAYS THERE FOR WEEKS ETC... AND YOU CANNOT REPAIR IT

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Thats bull, it doesn't stay there for weeks. It bleeds off in a couple of hours. There is no such thing as a perfect capacitor, they all have some internal resistance. The internal resistance will discharge the capacitor. The internal resistance is very high so the voltage discharges very slowly, it still only takes hours not weeks. :)

Newer ones yes, older ones, that 70,000 flyback voltage was still there 3 weeks after it was brought into the shop.

SO, better safe than sorry.

Thanks!

Well, other than a general look inside the case for obvious damage, etc., I have not looked inside the PS box. It's much easier (than the getting into the monitor) to lay the case on its side and remove the PS for a look. At least I can attempt to remove (find?) it as the cause. If it is the problem, it is amazing that I even have a MB! With that sound (it still rings in my mind!) it should have welded/melted all the wiring.

Any special precautions needed to look into the PS (other than disconnect power & don't touch stuff)?? BTW, this is an ATX PS, 300 watts that came with the Enlight EN7230 case.

If I see anything that might even be remotely unusual, it's outta there (peace of mind?). PS are cheap: http://tinyurl.com/6baol

janusz

That can be done. Just be safe!

On wrist straps: if anyone ever makes their own, put a 1 megohm resistor in series with the cable. That will allow it to function perfectly well by preventing static build-up, but will also limit the current that can pass through the body to a non-lethal level if you ever do touch a high-voltage source. As far as I'm aware most commercial wriststraps will have the resistor in them, but it would be worth checking with an ohmmeter.

I know you are probably not going to open the monitor up but in case you want to, dont.

You said you have a 3 year warranty on that thing. If they ever found out you opened it (or tampered with it in anyway) it would void your warranty.

;)

Hope you find out what was/is wrong :)

Quote:

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Originally posted by SuperSparks
On wrist straps: if anyone ever makes their own, put a 1 megohm resistor in series with the cable. That will allow it to function perfectly well by preventing static build-up, but will also limit the current that can pass through the body to a non-lethal level if you ever do touch a high-voltage source. As far as I'm aware most commercial wriststraps will have the resistor in them, but it would be worth checking with an ohmmeter.

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I wouldn't recommend making your own wrist strap, for that very reason. If you are using an anti-static wrist strap put it on your good hand. If you are right handed put it on your right hand. If you touch something you shouldn't it only goes to your wrist and then to ground though the wrist strap. If you have it on your other hand the electricity goes up one arm across your chest (heart) and down the other arm. If I am working on a live circuit I keep my left arm behind my back, I'm right handed. If I touch something I shouldn't it goes up my arm and down my leg, instead of across my chest and down my other hand that is holding the chassis. Oh and if you are watching somebody working on a live circuit don't stand behind them. They get the shock and you end up with broken ribs when there arm jerks back. :)

Is there a chance that this cracking sound came from the house wiring into which the computer was plugged into.

It maybe that you are looking in the wrong place.......you never know.

I agree, Philgo. I'm open to any possibility. I've asked my son-in-law (electrical contractor) to check it out tomorrow.

However, both computer systems are fed through one UPS (I bought it plenty big enough for both systems). Only machine #1 rebooted. The machine I was working on never blinked. I have switched connections on the UPS for each system and no problems. I have ruled out the UPS because it sits very close to me -- under the table. I built an elevated platform 6" above the floor that runs the length of my table - I place UPS, etc. on the platform - nothing on the floor (also makes it easy to vacuum). Whatever it is seems to be isolated to the one system. As you say, you never know. So, nevertheless, I am having my son-in-law look over both sets of receptacles on that wall. I have looked at the receptacles and do not find any indication of burn marks, etc.

After this post I am going to open up the case again and get a very close look at the PS. As someone famous once said, 'I'll be bak!"

janusz