PC Smoke

When you open the case it will probably be obvious.

If you do not see any burned, it's probably the power supply.

Your eyes and nose are going to be your biggest help after you get the box open. Of course the machine is UNPLUGGED when you are taking it apart.

I would talk to your local dealer...can be a bad power supply (most common failure).

John :-#)#

There a sound level detectors for locating sound. There are infrared detectors for location heat. There are volt meters for detecting voltages. There are scopes for detecting waveforms.

Are there smell detectors for locating burned components?

Yes. Your eyes :)

Does that several days mean that it is 'brand new' - those several days are the entire time you've had it?

Whoa! That must've been some pretty hot stuff you were copying :-)

Philo's PS sounds like a candidate.

If it is an OEM, naming the brand/modelno would be helpful to guide the case business.

Yeah.

Not sure whether you'd want a dog or a canary!

Mike.

OG formulated the question :

Burned run on the PCB?

Exactly, look for smoke residue. This may be problematic if 'smoke filled the room' was not hyperbole.

| Started the copy and the screen went blank and the room filled with | smoke. Smelled like burning resistor (I think). I have smelled that | smell before. | The only time I've ever seen that happen was with some kind of short that caused smoke and then soon after a resistor exploded. It overloaded all components, killing the RAM, hard disk, modem, CPU. Do not try to turn it on again. If there's anything left usable it should be removed and oput into a new box if possible. You could try just replacing the power supply, but I wouldn't do that with a valuable hard disk in place.

Power supply.

There is one chipset with a problem, then your source would be motherboard. The Intel ICH5/ICH5R could suffer latchup in the USB I/O area. Causing a short across the rails powering th USB pads. In an unlucky case, the bond wires on the pad with the latchup, remain intact, and a burned spot appears on the lid of the Southbridge. Since the Southbridge in that case, has no heatsink, it's easy to spot when someone tells you where to look.

(What a damaged ICH5/ICH5R looks like...)

But that hasn't happened since ICH5 era - no PCH seems to have suffered a similar fate. So Intel quietly figured it out. Back when those were happening, there might have been around 30 USENET posts from victims... I still own an ICH5, which remains intact. And I treat it like royalty :-)

If you were to take it to Geek Squad, they might well immediately pull the ATX supply, and connect up a spare supply. This is fine, if the spare is a decent name brand supply with full protections (so it can survive whatever the motherboard throws at it). But there might be a flaw which can damage a spare supply (like some rail to rail short maybe).

A question arises occasionally "should I try to use the defective computer again and again to collect more (smoky) symptoms?" . No, don't do that. One poster tried that while debugging his system, and the old flaky supply blew in spectacular fashion, damaging the motherboard. Meaning the repair went from from costing $50, to costing $200.

You can at least start with the "nose" test, and track down where the smoke came from. And PSU is likely to be the source.

Visual inspection only occasionally digs up a root cause for you. But visual inspection is cheap. And visual inspection is safe, *as long as you stay away from high voltage stuff*. The inside of the ATX supply, below the lid with the four screws, has a couple caps that are (potentially) dangerous. They hold enough energy, you *do not* use the screwdriver discharge method on them - it would deafen you if you tried that. Just stay away from them.

There is a reference schematic for a simple ATX power supply design here. R2 and R3 make C5 and C6 "safe". But if R2 or R3 fail open circuit, then the natural draining process provided by R2 and R3, might not actually be protecting you from high voltage. It is C5 and C6 terminals on the PCB, you do not want to touch... Only use a proper resistive shorting technique to make them safe (i.e. connect your own R2 and R3). It's better just to "look but don't touch" while looking inside an ATX supply... And don't forget to unplug the computer!!!

When you visually inspect the inside of an ATX supply, this is what you'd be looking for. I had an Antec, with low service hours, that looked exactly like that. The PC had been sitting in storage, on the main floor of my house (i.e. dry and warm), and the Antec caps started to leak while it was just sitting there. And I got a puff of gray smoke when I fired it up again. The capacitors on the motherboard, can also have domed lids and orange dried deposits on top. And that's mainly what a visual inspection covers. Only about 10% of potential faults are covered by a visual inspection, so it's not a "heroic method" by any stretch of the imagination. But visual inspection is "free" :-)

Of my three failed ATX supplies here, only one of them looks exactly like the Wikipedia article.

Paul

"OG" schreef in bericht news:ngaobc$1mh4$ snipped-for-privacy@adenine.netfront.net...

If you had copied by firewire I would have known the answer...

I've seen a well cremated PFC inductor in a PSU.

Since the PFC is basically a flyback boost converter, I just removed the MOSFET and linked out the inductor.

Some PSUs have a dirty great iron cored choke in series with the mains input for PFC - those are probably less likely to self incinerate.

Venting electrolytics can lay smoke like a Royal navy destroyer - but it usually doesn't smell like burning resistors.

Fry used Professor Farnsworth's smelloscope to locate Uranus.

Don't feed the dog liver & onion gravy if you're trying to isolate a smell............

I thought it was your nose.

Michael

A vinyl tube in the ear is the best way of locating strange noises in your car's engine bay too.

Yes. I had the displeasure of locating the source of a burning smell among a collection of immovable servers in a server farm. To make matters worse, there was lots of cooling air flow to disperse the smell. If there was any smoke, I couldn't see it.

So, I stuck a clear vinyl hose in my nose, and waved the other end of the hose around the fan exit ports on the servers. That isolated the smell to one server. I got permission to shut it down. However, when I opened the case, I couldn't see anything obviously burning. So, I did the vinyl hose trick again, and eventually isolated the smoke to the power supply. I didn't want to do component level troubleshooting so I just replaced the power supply.

Somewhat later, I bought am "air quality monitor". It's quite sensitive and will easily detect the smoke from a burning component. That came in handy when I noticed that something smelled like it was burning in my palatial office. I waved it around to sniff the various likely culprits and eventually isolated the smoke to the APC BackUPS XS-1000 in the photo. Notice the bar graph showing tilt.

Here's what's inside the Nikken AQM: Inside IR dust scattering sensor:

If your nose runs, and your feet smell, you're built upside down.

Years ago a colleague had a pimple on the end of his nose which he claimed made it much more sensitive and discriminating for detecting overheated components...

Mike.