Do I Smell a Toasted MB or PS?

**develguy** · 02-17-2009, 12:17 PM

Sorry in advance for the long post:

Looks like I toasted something, most likely it's the MB but maybe the PS too.

I am going to be testing each ASAP but wanted to post my issue so I can make sure I never do it again. Perhaps it'll save someone else a few hundred bucks in the future.

I have had phase 1 of my car pc (see sig) running smoothly for 3 or 4 months now. I needed to get a powered usb hub up to the front of my Explorer. So after doing some research and successfully bench testing a 5v run of wire from my bench atx molex connector (5v) to the hub connected to a laptop, I put the hub in the car and hooked it to the 5v a molex on the M2.

Here's what happend:

1. Started the car, pc fired up as normal, Centrafuse resumed from hibernation and I got music.

2. The led on the hub was lit and I measured 5v at a random hub socket.

3. Added a thumb drive to the hub and did not get a light on the drive and it was not recognized. The hub connects to the pc through an added 2 usb port hooked to the 3/4 header on the MB. I was having some hot swap consistency issues with this previously and read that I may have it plugged in the header wire(s) backwards, so...

4. While everything was still running, I pulled the usb cable (not the header wire) from the back of the pc... The pc locked up, no music and the Centrafuse screen froze.

5. I don't have a reset switch installed (I know, stupid!) so I turned off the ignition.

6. I could still hear the pc running so I pulled the case/M2 power plug as I had several times before w/out problems. Waited about 5 seconds and plugged it back in.

SPARK!

7. I noticed a small spark near the base of the plug as I plugged it in. I knew that could not have been good.

8. With a sick feeling in my stomach, and the engine still off, I decided to flip the both of the usb header wire connectors and try to restart it.

9. Start the motor, nothing, no post, monitor, nothing.

10. Went to the back of truck to see if anything was running, etc and got a wiff of the magic smell and instantly yanked the power plug.

So now, I'm trying to first figure out what I did wrong and second try to figure out what I toasted. The monitor thankfully is fine!

Does anyone have any advise on what I could have done differently? I probably could have disconnected the battery or at least the fuse at the dist block before unplugging/plugging the power plug but I have managed to unplug/plug before w/out problems.

Could the spark have been static enough to fry something?

Was there maybe some stored power somewhere that could have surged when I plugged back in???

Thanks in advance for any advise!

**Bugbyte** · 02-17-2009, 02:21 PM

Check fuses first. Disconnect PSU from computer, check to see if it is working.

If working, look on mobo for anything that looks 'blown'. Try powering it with a known good PSU, maybe on the bench.

P.S. - Welcome to the hobby. I fried $500 worth of LCD screen from a static spark.

**develguy** · 02-17-2009, 04:37 PM

Originally Posted by Bugbyte

P.S. - Welcome to the hobby. I fried $500 worth of LCD screen from a static spark.

Ugh! That hurts!

Will test the PS and MB ASAP.

Any ideas on what I could have done to have prevented this?

**PaulF** · 02-17-2009, 05:29 PM

There may have been a short in your wire, or the line you powered it off could not supply an adequate amount of power for what you wanted. The USB cable from the computer was probably still getting power from the computer which is why it didnt fry until you pulled out that USB cable.

What connector on the power supply did you use to power this?

**develguy** · 02-18-2009, 09:15 AM

Originally Posted by PaulF

What connector on the power supply did you use to power this?

I hard wired it to the 5v rail of a molex connector.

**PaulF** · 02-18-2009, 09:32 AM

Did you ground it to the same rail?

**develguy** · 02-18-2009, 09:38 AM

Originally Posted by PaulF

Did you ground it to the same rail?

Yup. One thing though... The 12v (and ground) rail of that same molex from the M2 is hard wired to my monitor.

**miko55** · 02-18-2009, 09:54 AM

Remove power supply cable, hit on buttom a few times, reattach cable, hit on button.
Do you have a fuse in first few inches from battery? Get one.

**develguy** · 02-18-2009, 10:27 AM

Originally Posted by miko55

Remove power supply cable, hit on buttom a few times, reattach cable, hit on button.
Do you have a fuse in first few inches from battery? Get one.

I don't have an "on" button (or reset) on this pc yet... The M2 power supply is triggered from the truck's ignition status.

The 4 gauge power cable from the battery to the back of the truck is fused at the battery -and- at a fused distribution block near my amps and pc.