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| USB Memory Stick not detected http://forum.hddguru.com/viewtopic.php?f=10&t=21333 |
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| Author: | DanR [ December 5th, 2011, 10:39 ] |
| Post subject: | USB Memory Stick not detected |
Hi guys, Haven't done much work on USBs so I'd thought i'd ask for your input. - 4GB usb stick. - PC does not detect any USB nor does the LED light up. - No obvious burn marks. - All fuses seem intact. - Possible crystal oscillator? Any suggestions? Thanks in advance. DR |
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| Author: | hddguy [ December 5th, 2011, 10:56 ] |
| Post subject: | Re: USB Memory Stick not detected |
DanR wrote: - Possible crystal oscillator? This would by my guess, but accurate diagnosis is near impossible without seeing the media |
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| Author: | ici_lemmy [ December 5th, 2011, 11:54 ] |
| Post subject: | Re: USB Memory Stick not detected |
DanR wrote: - Possible crystal oscillator? Would also be my first try. Easy to test with an osciloscope ! If the oscillator is working, then my guess would be the controler and you'll have to work on the memory chip ! |
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| Author: | Vulcan [ December 5th, 2011, 14:55 ] |
| Post subject: | Re: USB Memory Stick not detected |
@DanR: It may be helpful to know the history of that USB drive, leading to the current situation. |
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| Author: | DanR [ December 5th, 2011, 16:48 ] |
| Post subject: | Re: USB Memory Stick not detected |
@Vulcan Unsure of history but there have been no previous DR attempts. Plug USB into computer and you get nothing. @ici_lemmy Tested using an oscilloscope. Was showing no 12MHz, so I presumed it dead. Replaced the crystal and still no 12MHz output. This leads me to think that the micro-controller is now dead. |
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| Author: | pcimage [ December 5th, 2011, 16:53 ] |
| Post subject: | Re: USB Memory Stick not detected |
DanR wrote: @Vulcan Unsure of history but there have been no previous DR attempts. Plug USB into computer and you get nothing. @ici_lemmy Tested using an oscilloscope. Was showing no 12MHz, so I presumed it dead. Replaced the crystal and still no 12MHz output. This leads me to think that the micro-controller is now dead. In which case you'll need to remove the flash chip, read it in and reconstruct the data. |
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| Author: | Vulcan [ December 5th, 2011, 17:20 ] |
| Post subject: | Re: USB Memory Stick not detected |
@DanR: Thanks for the reply. DanR wrote: Unsure of history That's a shame for you, as having that info often helps troubleshooting, in my experience. DanR wrote: Tested using an oscilloscope. Was showing no 12MHz, so I presumed it dead. Replaced the crystal and still no 12MHz output. This leads me to think that the micro-controller is now dead. There can be other reasons for your reported measurement, not only a dead controller. As you've already seen, pcimage has explained a classic DR approach, if you are unable to repair the original USB drive. Good luck! |
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| Author: | DanR [ December 6th, 2011, 7:14 ] |
| Post subject: | Re: USB Memory Stick not detected |
Taking the chips down to the lab tomorrow. Will post results (if any) |
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| Author: | ici_lemmy [ December 6th, 2011, 11:27 ] |
| Post subject: | Re: USB Memory Stick not detected |
There is no reason that the memory chip is dead. So you will have result but the difficult part is to reconstruct the data... |
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| Author: | dick [ December 6th, 2011, 13:35 ] |
| Post subject: | Re: USB Memory Stick not detected |
Before doing anything drastic I would also always check the 4 contacts from the usb connector to the pcb for continuity. And it is a good idea to check for +5v and then check the +/- data lines to the controller. |
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| Author: | fzabkar [ December 7th, 2011, 21:43 ] |
| Post subject: | Re: USB Memory Stick not detected |
Can you measure any voltage on the memory chip's Vcc pin(s)? Is there a discrete 3.3V linear regulator IC on the PCB? |
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