Computer wont start - bad smell

Chris_5339762

Just wondering if anyone has seen this before. I had a computer in sleep mode, and plugged a keyboard into the USB slot. However, due to a crappy, loose slot, I put the USB in backwards. The computer would not start.

There is a light on the front of the computer, but upon pressing the power button there is no fans, no POST, no activity. Its as if I hadn't the power cable in.

There is no obvious sign of burning on the motherboard but I suspect the problem is coming from the CPU area as thats where the smell seemed to be coming from.

Has anyone seen this before? Whats the best way to isolate and test this? Email sent to HvS where I bought it from, but they are notoriously bad at replying and I am dreading the fight I'm going to have

8GB-Kit Corsair Vengeance DDR3 1600 MHz CL9
ASRock B75 Pro3, Sockel 1155, ATX
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BitFenix Shinobi Midi-Tower USB 3.0 black, ohne Netzteil
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Samsung SSD 830 128GB SATA 6GB's Paper Box
Sapphire HD 7870 2GB GDDR5 PCI-Express
WD Caviar Green 1TB, SATA 6Gb/s (WD10EZRX)

chrismon

How did you get the USB in backwards?
Did the computer turn off straight away?
Where is the smell coming from?

Chris_5339762

USB went in backwards as the plastic connector in the middle of the plug at the computer end was slightly off to one side, allowing the plug to fit in with no more force that a well-fitting plug was require

Computer was in sleep mode at the time with all fans off. Noticed all lights were off after I'd plugged it in. Power switch does nothing at all now.

The smell is going now, but while I could smell it the best I could say is that it was near the CPU.

All that said, I took out one of the HDDs and plugged it into another computer and now that wont start. This is getting bizarre and very expensive.

Torqay

Since the computer doesn't come on, there is no way of testing anything until you try another motherboard. If you're lucky, it's just the MB that's blown. Shortcuts can do quite some damage. You should have the MB replaced when you discovered the "crappy, loose slot" rather than sticking something into it. HVS might replace the MB but certainly nothing else, should it become necessary.

Chris_5339762

The loose slot was on the exterior of the PC case, not one of the 'internal' USB ports - should have mentioned that. I have sourced another power supply and will try that.

Its not the HDD either, that was my own stupidity.

phily2002

Check the dodgy usb port that the pins aren't touching(when you put the stick in it probably knocked them together. This would cause the pc to trip/not switch on. If they are, just seperate them with a small screwdriver(when unplugged), or better remove the cable that goes from them into your motherboard
The dodgy smell coming from the board is unusual, normally its the psu that would give a funny smell when it blows...
sounds like one at least is a gonner, hopefully not the 2...

You likely shorted the USB port, and blown one of the USB fuses.

Google for pics of USB fuse and then try to identify them on your motherboard. You were using the internal USB headers so usually the fuse is close to the motherboard header.

The fuse will have protected the rest of the mobo from damage.

hearny

Sounds like you shorted the USB port as suggested.

Look at the manual for the Motherboard here:

ftp://europe.asrock.com/manual/B75 Pro3.pdf

On page 13 you will see the connections.

You say the USB port was on the case so its more than likely connected through the cables going into number 8 if its USB 3 or number 23 or 25 if its USB 2.

Disconnect the relevant cables from the board and see will it start up.

Chris_5339762

I'll try that tonight and will let ye know. Second PC is fine as I've said, both HDDs have had data backed up too, my regular backup was 2 weeks old.

Will take the computer down home this weekend and change the power supply too, see if that does anything.

Antar Bolaeisk

I thought USB ports had a resettable fuse in them? They're also meant to be fully short circuit protected according to the USB specification if I remember correctly. Any time in the past when I've been playing around with USB ports, normally just to pull power from them, if I did something wrong it would just pop up on the computer that the USB hub has malfunctioned.

I'd try maybe pulling the battery from the motherboard and disconnecting the power (note: do it the opposite way around) and leave it for a good half hour in case the fuses need some encouraging to reset (not that they should).

Edit: just looking about to refresh my knowledge of USB ports and came across this: http://www.badcaps.net/forum/showthread.php?t=3036

Sounds similar to your experiences Chris (bar the not booting bit).

H3llR4iser

I'm inclined to go with Antar's suggestion; Also simply try disconnecting the "offending" usb header from the mainboard, it might be that the plastic thing snapped further and now two (or more) of the USB contacts are touching each other.

Motherboards/PSUs are usually protected quite well against short circuits, hopefully you didn't incur in "that one case in a thousand"...

Chris_5339762

Tried all this tonight but didn't work. Next step is to bring the computer down to Cork with me next weekend where I have a spare PSU which I'll try. Apart from that it'll be a fight with the manufacturer in Germany, who doesn't seem all that willing to answer emails....

Chris_5339762

Slight update. HvS want the entire system back for repair but for sanity reasons we're not going to ship it back to Germany even though we would be entitled to.

Took everything out of the system the other night at home (with a backup person!) and tested the power supply. All voltages ok and CPU fan works when ATX power ribbon pins are shorted when the power supply is connected to the motherboard. Also tested that a signal is coming from the power switch and 'arriving' at the motherboard. The small board that holds the power switch and USB controller of the computer is fine too. A detailled look at the motherboard, CPU and power supply shows no evidence of any burning whatsoever.

Result: We have ordered a new motherboard as it seems to be the only source of all the problems. PSU is fine, all connections seem to be fine, motherboard appears to be dead. Its receiving a signal from the power switch of the computer but isn't 'sending' that information to the main power supply to turn on the computer.

No idea where the smell of burning came from however. No visible damage. Buying a new, identical motherboard is a gamble but won't break the bank. As I said earlier, PC is only seven months old so a bit soon for an upgrade.

Chris_5339762

New motherboard arrived and my dad was kind enough to hook everything up to it. Pressed the power button and fans started which is great! HDDs still have to be connected and we'll connect it temporarily to the TV as I'm not hulking my monitor down home.

Looks good, fans starting is more progress than before! Heres hoping the CPU and video card are both alright but it does appear something went bang on the original motherboard.

You need to make sure it doesnt happen again. If the front panel USB port is broken then get a new one from the case manufacturer.

Chris_5339762

Since I got it from Germany and their response was to send the entire thing back, I reckon a piece of tape over the offending USB ports and even the purchase of a USB hub will be a good fix!

Chris_5339762

New motherboard in, computer boots as normal! Problem solved, all working again. Had a good look at the old motherboard under a magnifying glass... can't see anything at all wrong with it. No broken/burnt tracks, no capacitors gone bang...