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Connecting USB peripherals/external display lead creates SPARKS?!

peanutismint

peanutismint

macrumors 6502
Original poster
Apr 4, 2007
437
9
Cardiff, UK
I've had this problem for a while now with my unibody MBP - when I connect USB peripherals or my external display via the mini displayport adapter, I get small sparks where the connector touches the laptop body around the port. This also causes pops on my speakers and also flashes on my external display (if it's already connected while I'm inserting a USB lead, for instance).

I'm guessing this isn't normal?? But I can't seem to see what would be causing it. It happens both when AC powered or just running off battery, so I may be able to rule my electric mains out of the equation??

Any ideas???
 
I get the same thing on my 15" MBP, It sparks from the chassis to the ground (outside) of the usb connector. It may just be something that is generic, because i know my mates windows tower does it on the motherboard ports...

Never had any problems with my monitor to think of it (but who knows, maybe i'm missing it). I only have troubles when the displays connected and i resume from sleep. (fuzz, and no pic, restarting the monitor fixes this) haha.

EDIT: I get all kinds of pops and the like from all sorts of things in my mbp, not to mention the switchmode noise when connected to my mixer etc... so i won't go there, but I get what you mean about the speakers...
 
Same here on my MBP15. USB and Mini Displayport both do it, if they come in contact with the case of the MBP I get tiny sparks.
No display or sound issues tho. I kind of assumed it was normal, just like the "tingle" through the chassis that you get under certain circumstances.
 
Cool, thanks guys! The general consensus seems to be that it's reasonably normal, which I figured it might be, just wanted to be a bit more convinced so thanks! :)

Fubar1977 said:
I kind of assumed it was normal, just like the "tingle" through the chassis that you get under certain circumstances.
Click to expand...

I've been feeling this too!! If I rub the tip of my finger across the 'blank' areas either side of the trackpad, I feel a definite 'hum'. This is actually another thing that made me wanna check that I'm not the only one experiencing this! :eek:
 
It happens with external devices that come with their own power-switch unit (won't happen with an USB hub that is not plugged into a PSU). It happens with 2008/09 Unibody Macbooks, no idea about 2010 ones.

The voltages should only be between 5-15v even when you see sparks, but there is one major issue, which the Apple Store in my town is currently investigating after 22 months of getting Apple to acknowledge it:

The moment you touch the Macbook with the ground connector of PSU driven USB/display devices the ExpressCard slot can create drop-outs that leads to all kind of issues with ExpressCards: data corruption, Mac hangs, Kernel Panics.

On 08/09 MBP it seems to be worse when the 9600M is active compared to the 9400M.

Furthermore my personal experience/suspicion is that these electrical issues even happen without the external touching/connection, but more sporadically and thus less reproducible.

That all being said it also depends on the kind of device you are connecting and the electrical build of that device. For example it can well be that the grounding parts of your USB/display connector already carry a small voltage by themselves. And with one external eSATA HD I noticed that the issues are worse when I connect the HD directly (eSATA-to-SATA cable) compared to connecting it via its enclosure (eSATA-Oxford bridge chip-SATA).

Nevertheless it should not happen and is a clear production error aka malfunction. :apple:
 
Wow cool, thanks for that information - good to know it's a known problem. Obviously it'd be really easy for :apple: to say in a situation like this 'well everyone's home mains supplies are different so it could be any number of things wrong with your power, the sockets, the wiring, the local substation....'. I'm not bothered as such by the sparks created, I just don't want them to be indicative of a bigger problem, one which is going to end up damaging parts of my hardware, causing data loss or, even worse, causing me or others harm via mild electrocutions! :)
 
I would not call it a "known problem" nor does Apple have any official stance to it yet. But when you go to an Apple Store with a frozen Mac in your hand and then demonstrate how the thing freezes again once you touch the USB port they can hardly deny the evidence anymore (again: after 22 months of rather useless telephone negotiations).

One thing you could test is to connect an external Firewire HD and see if the problem still occurs. This seems to have an impact on the whole electrical situation.

My MBP is at the Apple store for nearly 3 weeks now, because the FW thing first made the issue unreproducible. They seriously wanted to give me back the MBP as "repaired" because of that (and because they ignored that I gave them a completely fresh OS X installation on the internal HD), but I reminded them how I demonstrated the issue in *their own shop* and that the FW HD bootup would change the whole electrical situation.

They are trying a new Logic Board (again), after which we will decide how to go on (already had a Logic Board changed with my original 15" 2008 MBP and later the MBP exchanged for the 2009 one).

As long as you don't have/use the ExpressCard port and don't experience freezes/kernel crashes it shouldn't concern you too much though. If you use that slot you should test it against errors and tell Apple about it.
 
Nah mine's a 2009 model without the ExpressCard slot so should (hopefully!) be fine. I will try the firewire HDD suggestion though.......
 
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