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 Posted: Apr 12, 2012 - 03:04 PM |
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Joined: Oct 18, 2001
Posts: 358
Location: Eastern England.
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...you manage to toast an AVRISP mk2, the port of the USB hub it's connected to and your Saleae Logic 8.
Note to self - the tabs on voltage regulators aren't always a handy 0v reference point. Some of them are connected to the main 36v 5A power rail. So when you connect the programmer to one which is at 0v and the Logic 8 to one at 36v you can get quite a current flowing.
Oh well, I didn't want to make a profit on this job. |
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Posted: Apr 12, 2012 - 03:12 PM |
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Joined: Oct 10, 2007
Posts: 395
Location: Valls, Spain
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Ooohhh man...
That's true, some regulators have the tab connected to the voltage input... This could have happen to anyone, is easy to forget a small details like that one. My condolences to your lab equipment... |
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Daniel Campora
http://www.lear.com
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Posted: Apr 12, 2012 - 03:39 PM |
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Joined: Mar 27, 2002
Posts: 18545
Location: Lund, Sweden
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Quote:
toast an AVRISP mk2, the port of the USB hub it's connected to and your Saleae Logic 8.
Ouch!
The wise thing you did was never to attach any development tool etc (i.e. the Salae and the mkII) directly to a computer. Always a hub in between.
Always.
Not a guarantee, but it lowers the risk of frying the PC itself. An expensive fuse, but cheaper than a new PC... |
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Posted: Apr 12, 2012 - 04:12 PM |
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Joined: Jun 15, 2009
Posts: 134
Location: Northern California
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JohanEkdahl wrote:
The wise thing you did was never to attach any development tool etc (i.e. the Salae and the mkII) directly to a computer. Always a hub in between.
A good idea in general, but I've had USB test equipment and debuggers that would not work when plugged into a hub. They needed to attach directly to a motherboard USB port. |
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Posted: Apr 12, 2012 - 04:15 PM |
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Joined: Mar 27, 2002
Posts: 18545
Location: Lund, Sweden
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Quote:
A good idea in general, but I've had USB test equipment and debuggers that would not work when plugged into a hub. They needed to attach directly to a motherboard USB port.
Could that have been equipment that needed more than the basic 100 mA over the USB supply, and the hub had no power of its own (i.e. a wall wart)? |
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Posted: Apr 12, 2012 - 04:46 PM |
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Joined: Nov 11, 2003
Posts: 3880
Location: Chicago Illinois USA
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| Good point. I'll get a hub. |
_________________
Discursive design,
Torby
Some days, it's just not worth chewing through the restraints.
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Posted: Apr 12, 2012 - 07:12 PM |
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Joined: Oct 18, 2001
Posts: 358
Location: Eastern England.
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danicampora wrote:
Ooohhh man...
...some regulators have the tab connected to the voltage input...
Thanks for the condolences!
In my case it was an LM317 (wired as a current current source) so I'd connected to the Vout terminal. |
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Posted: Apr 12, 2012 - 07:20 PM |
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Joined: Apr 20, 2007
Posts: 6066
Location: Long Island New York
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Quote:
...you manage to toast an AVRISP mk2, the port of the USB hub it's connected to and your Saleae Logic 8.
Ohhhh that hurt!!  The MKII loss sucks, but the Logic 8 is a kick in the Ballocks.
I have a saleae8 Great unit!!
Contact them and tell them what happened. I have found that they are pretty generous with repairs through some of the forums I come across.
You might be very surprised what they respond with....Only sayin'  |
_________________
Jim
I have decided that I am no longer going to plan anything in advance. In a court of law this is called Pre-Meditated, and does not look good for the defense.....
Timer function not working properly? Check CLKDIV8 Fuse first
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Posted: Apr 12, 2012 - 09:40 PM |
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Joined: Oct 18, 2001
Posts: 358
Location: Eastern England.
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jgmdesign wrote:
Contact them and tell them what happened. I have found that they are pretty generous with repairs through some of the forums I come across.
Thanks for the heads-up, I'll do that.
I have bought a new unit as I need to get this project sorted ASAP and I'm chasing down comms issues - RS485, 115k data, half-duplex, multi-drop, 1000' cable runs, power down the data cable to the slaves... At least with a second unit I'll be able to send the broken one back to them and not worry too much about shipping times.
And a second unit is a nice luxury to have in the laptop bag - luckily I had a second AVRISP in there which kept me going today. |
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Posted: Apr 12, 2012 - 11:32 PM |
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Joined: Apr 20, 2007
Posts: 6066
Location: Long Island New York
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YOu have to love the pre loaded serial type ocnfigs that you can use. And the ability to have the packets decoded and on top of each byte.
My big HP can do it but not so easy.
Best $200 I ever spent |
_________________
Jim
I have decided that I am no longer going to plan anything in advance. In a court of law this is called Pre-Meditated, and does not look good for the defense.....
Timer function not working properly? Check CLKDIV8 Fuse first
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Posted: Apr 14, 2012 - 03:55 PM |
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Joined: Oct 29, 2006
Posts: 2758
Location: Sweden
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Quote:
You know it's time to stop work for the day when...
I did repair work on a mixing console a couple of months ago.
The transformer was attached to the bottom plate, so in order to work with it I had to have it standing upright on my workbench.
At 2 o'clock in the night I was finished, everything worked again.
Of course I managed to bump into a lamp which in turn made the console fall flat on the table on its knobs.
Just beside where it fell on the workbench was my newly purchased desktop computer.
The computer had turned itself off and any attempt to restart it only resulted in some leds blinking.
Pretty devastated from that discovery I decided to see how the console survived.
So I put my headphones on and started testing channels.
No matter what channel I tested all I could hear was a load hum noise.
This made me even more devastated. Not only had my new computer died but the audio console seemed to have suffered severe damage falling on its belly...
I returned to my desktop and low and behold the start-up screen showed up. After another ten or so times it actually made it all the way.
Back to the mixing console.
In my distress I forgot that the audio was routed via the desktop so the hum noise was coming from the turned off computer. With the computer back up every channel was working again.
Took me nearly 2 hours to get to that point.
Still not sure what happened to my desktop.
A chunk of the hard drive teared off?
A G sensor in the computer decided that I was disqualified for half an hour?
I did go to sleep with some sort of grin. |
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Posted: Apr 15, 2012 - 12:45 PM |
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Joined: Jul 02, 2005
Posts: 5939
Location: Melbourne, Australia
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| I bet you aged 15 years ... |
_________________
Ross McKenzie
ValuSoft
Melbourne Australia
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Posted: Apr 15, 2012 - 01:56 PM |
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Joined: Oct 29, 2006
Posts: 2758
Location: Sweden
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Quote:
I bet you aged 15 years ...
Yes, I was chocked when I looked into the mirror next morning.
That is, a bit more than the experience I'm used to every morning. |
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Posted: Apr 18, 2012 - 02:25 AM |
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Joined: Apr 24, 2006
Posts: 283
Location: Sydney, Australia
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I was trying to measure the voltage differential across a motor drive IC, and connecting the oscilloscope probe and ground leads across the load seemed like the immediately obvious thing to do.
Except when the motor was off, both sides of the motor were held at 24V with a SMPS behind them. Grounding one side flowed a lot of current through the drive IC and it exploded quite impressively. Thankfully no damage to the CRO!
Of course I know the correct way (probe on each side with the display set to A-B) but there's always room for a brain fart when you are thinking about other things. I had assumed that the "negative" side of the motor was at ground potential. Nope! |
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