SheevaPlug won't power up

[philv]

Hi Everyone,

I had received my SheevaPlug early this week, and had not had a chance to experiment with it much until last night. When I plugged it in the first time, and subsequently last night, everything worked properly, I was able to access the serial console and even managed to ssh into the installed Jaunty.

I left the SheevaPlug on overnight, and it would seem that sometime overnight it failed. When I got up this morning, the blue LED was off and the green LED was flashing -- it was like a capacitor discharging, as it wasn't an immediate on/off, but rather it went bright then gradually faded to dark. I opened it up to check the voltages on the power supply, and they seemed to be within the 5.8-6V range, which I believe is OK for the regulators on the board, based on the data sheets. As well, the LEDs on the ethernet jack flicker on and off briefly, at the same time as the green LED does. The FT2232 doesn't even enumerate anymore, so I presume something has failed catastrophically.

At the same time overnight I had a DBAu1200 plugged in (to the same power bar, even) so I don't really think it was a power related issue that caused the plug to fail.

Does anyone have any suggestions, or has anyone seen similar symptoms before or is it time to get in touch with Globalscale's technical support team?

Thanks a lot!

[dattaway]

I would take an oscilloscope and check for noise on the power supplies.  And check to make sure the clock signal is clean.  Check for a proper reset sequence and watch for signs of things initializing.  Might be a bad connection or something.

[philv]

Well, I took some time to look at the power supply. Turns out it is indeed the power supply that has failed. There are roughly 1V differences in voltage over a period of about 1 second.



This is what I saw on my scope. I was measuring the power input to the SheevaPlug motherboard, which I suspect is supposed to be somewhere around +5V -- the transients seem to push this to about +7V. Whoops. Explains the LED behaviour, I suppose (interestingly, the transients I'm seeing occur at the same frequency as the LED is blinking). Notice that this is over a 2 second period.

Time to email Globalscale Technologies support, I suppose.

EDIT: fixed typo.

[spike]

This is quite alarming seeing a 7V spike on a 5V rail.  40% rise is voltage is too much.  Have you checked the power supply block as to what is really causing this spike?  The decay may be due to the filter capacitor discharging but its kinda strange that it fails to filter a specific harmonic.

Have you also checked the mains whether you see some fluctuations?

[philv]

This is quite alarming seeing a 7V spike on a 5V rail.  40% rise is voltage is too much.  Have you checked the power supply block as to what is really causing this spike?  The decay may be due to the filter capacitor discharging but its kinda strange that it fails to filter a specific harmonic.

Have you also checked the mains whether you see some fluctuations?

Yeah, mains is clean. I have far more sensitive dev kits I run off the same power strip, even, so I suspect it was a manufacturing defect.

FWIW, my replacement SheevaPlug arrived yesterday from GTI. I'm so far very impressed with their service and speed. :-)

[mutzel]

I'm having the same issue. Mine was running overnight for 10 days.

Are there others having the same problem or is it an exception that the SheevaPlug is dieing if running permanent?