Destroyed my TinyGv7 and laptop tonight.

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  • November 22, 2014 at 12:04 am #7004
    complacentsee
    Member

    While playing around with my TinyG tonight I managed to destroy both my laptop and my TinyG.

    Not 100% sure what happened but I pluged in the USB cable and a small amount of smoke came off the ground trace next to the USB port/FTDI chip.

    Unplugged the cable but the damage was already done. Looks like my power supply has a strange common terminal configuration where the positive terminal is referenced to ground and the common terminal actually floats negative.

    Did a bit of digging on the board with my oscilloscope and found the USB data pins had the power supply voltage on them. Took off the FTDI chip and the data lines returned to normal but the ground trace was indicating negative power supply voltage when compared to the USB housing.

    Not sure what changed tonight versus the other times I used it that caused the issue. I’m assuming it was an issue that solenoid caused a looped between the odd rail configuration on the power supply and my laptop USB.
    It looks like I’ll be laptop, Tinyg and power supply shopping in the near future. I’ll probably pickup a USB hub just in case.

    November 22, 2014 at 7:02 am #7005
    cmcgrath5035
    Moderator

    Well ouch, that’s not a fun way to end your CNC session.

    I have been a bit concerned myself as I research adding a DC spindle to my machine, which means a direct 3.3V logic connection to the spindle controller, which in turn has its own 48V power supply and “not always clear” polarity and ground references for the spindle drive side.

    The USB Hub is a good idea, but I’m not sure I trust a run of the mill low cost hub to necessarily provide the desired isolation either.

    Anyone else with experience here, and good solutions, please comment.

    November 22, 2014 at 6:22 pm #7006
    complacentsee
    Member

    I think im going to use the Advanced Devices chip to make sure I’m isolated in the future. Shouldn’t be to big of a pain to make work as I just need to pull 5v and ground to the isolator. They are priced pretty competitively.

    November 22, 2014 at 8:08 pm #7007
    cmcgrath5035
    Moderator

    Post a link to your schematic/strategy.
    Others may be interested.

    November 22, 2014 at 10:31 pm #7008
    complacentsee
    Member

    Basically it would be using an Analog Devices ADuM4160 USB digital isolator.

    I tossed my eagle schematics and board files for a prototype on my github account. User complacentsee/USB-Isolation. It’s just using the recommended layout and hasn’t been tested. I just ordered the prototype from OSHpark tonight and will test once sometime December.

    The upstream side of the ADuM4160 gets power from the host device, in this case your computer. The downstream side of the ADuM4160 will need to get it’s power from the TinyG driver boards 5V rail.

    Last night my TinyG was still working (FTDI was destroyed but uProcessor and drivers working) until I killed the 7805. Hopefully I can replace a couple components and get it running. The solder mask is damaged but the traces all look good.

    November 23, 2014 at 7:39 am #7009
    cmcgrath5035
    Moderator

    Quick look around finds the AD eval board and this

    Pecs are a tad confusing. USB2 compatible, but only up to 12Mbps.

    November 23, 2014 at 10:11 am #7010
    complacentsee
    Member

    Yeah. They are USB 2.0 full speed and not high speed. The FTDI on the TinyG indicates its full speed on the data sheets.

    The chip can do low speed and full speed but needs manual selection. I jushard circuited mine for full speed and decided to take the 5V directly from the TinyG instead of dealing with another adaptor. Plus I didn’t want to have another adaptor that may for some reason reference ground differently and protect the PC but not the TinyG.

    November 29, 2014 at 8:23 am #7048
    cmcgrath5035
    Moderator

    When you have some time, give this thread a read

    The wireless alternative…..

    • This reply was modified 9 years, 11 months ago by cmcgrath5035.
    November 29, 2014 at 4:09 pm #7050
    complacentsee
    Member

    Thanks for the link. Amazon has one available on prime so I had to pick one up. I think I’ll be able to repair my unit with something like that.

    Right now it looks like functional again now that I have the 5 volt rail repaired but the microprocessor lost it’s program or needs to be replaced.

    November 30, 2014 at 7:22 am #7054
    cmcgrath5035
    Moderator

    Right now it looks like functional again now that I have the 5 volt rail repaired but the microprocessor lost it’s program or needs to be replaced.

    That sounds like a tough job; I have seen it done (QFP replacement) but very difficult with the usual hobby soldering tools. I assume that you think the bootloader is gone?

    December 9, 2014 at 8:25 pm #7143
    complacentsee
    Member

    Unfortunately the repair didn’t go as planned. I didn’t have any issue replacing the mcu but it doesn’t run. I can flash xboot onto it and it verifies but it can’t be flashed with avrdude. I flashed the full firmware onto it but that either doesn’t work or only responds with errors serially.

    Not sure if it is my AVRISP clone or some other issue. Perhaps my board is damaged.

    December 9, 2014 at 10:14 pm #7147
    cmcgrath5035
    Moderator

    Bummer.

    Surge events can lead to difficult/impossible to find problems.

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