Poll: Sheeva Plug Power Supply failures - does the mains voltage matter?

[c128]

I'll have to add my vote for a Sheevaplug where the PSU has failed in around 6 months running semi-continuously on 240V .

Yesterday I woke up to find that my Sheevplug-based fileserver was unavailable and that the MCB in my consumer unit dealing with the socket it was plugged into (with other things) had tripped.

Checking everything out, and it was one of my Sheevaplugs that had failed - burnt smell coming from the casing, no lights, fuses intact.  Everything else connected to the same surge protector strip (another Sheevaplug, router, modem, Gigabit switch) were all fine.

The plug in question is about 6-7 months old and was connected to a (powered) multi-disk USB enclosure; the SD card with a  Debian install appears to be fine.

For now I've resorted to bringing up an old NSLU2 with Debian and connected that to my USB enclosure just to give me a fileserver again - forgotten just how slow an NSLU2 is running Debian though :-( .

NewIT, where I bought my plugs from, replied very promptly and said that they are expecting some PSUs in from Globalscale within a few weeks and will contact me, so I guess I'll have to wait and see where this goes.  Were it not for the warranty, and sticker covering the casing to enforce it, I'd have opened it up to have a poke around, but from the burnt electrics smell I'm pretty sure it's a blown capacitor or some such.

[cjm]

The new one has been OK so far but whenever I plug in the power lead there is usually a small spark which is a bit worrying.

[Simple] switching power supplies draw a high amount of current when connected to mains until the capacitors have charged up and this can cause a sparc. All this assuming, of course, you connect it when the AC is not currently 0V (every 100th/120th second at 50/60Hz) but this can hardly be controlled

Perfectly normal...

Thanks,
--Christian

[plagervall]

I just contributed to the poll. Plug stopped working due to power supply failure after about 8 months of continuous usage. In my case, 110V system. No obviously damaged components on the PS PCB. However, measuring with a multimeter on the 5V output (main board disconnected) it is clearly observed how the 5V line is "jumping" back and forth between 0V and 5V (almost). This explains why the LEDs were blinking before I took the device apart.

It was great to find this problem covered in this user group as it saved me a lot of time to find the cause. So far I have been unable to find a circuit diagram for the PS design. In fact, I have not been able to identify the model/part number yet even though it appears to be a Haosenda International built part. Anyone that has more technical information for this particular Power Supply?

[dattaway]

120 volts and one year.  The final output capacitor jetted its oil onto the board.  1000uF.  Replaced and its good as new. 

I also replaced the other two large capacitors since I had them.  But I added extra ventilation to keep the heat from destroying it again.

[robertut]

See my post here about external PSU from eBay, much cheaper and better:
http://plugcomputer.org/plugforum/index.php?topic=1735.msg15574#msg15574

[nhoeller]

A SheevaPlug that had been running continuously as a squid, backup and file server (externally powered USB drive) failed earlier this week - blinking lights, random restarts and finally nothing.  Fortunately, I stumbled on this forum.  The power supply looked OK, although the tops of two of the smaller capacitors seemed to be a bit bulged.  Unloaded voltage read 5V.  I plugged the power supply into the circuit board and got a green LED.  However, output voltage of the power supply dropped to 3V and then cycled between 0V and 3V.  Fortunately, I run Linx off an SD card and had a spare SheevaPlug, although it took a while to clean up the file systems on the external harddrive.

Just to confirm, can I safely replace the power supply with an external 5V/3A regulated power supply?  I assume there is nothing special about the two pairs of wires - it is hard to tell from the power supply with all the brown glue, but it looks like the black wires are soldered together and the two red wires are connected through the circuit board.

Best wishes for the holidays,
Norbert

[restamp]

I believe you are essentially correct, Norbert.  I think 5V/2A is all that is theoretically needed, but 3A would give you a bit more of a safety margin, and is what I would prefer.  Just remember:  Red is +, Black is -.

With all the SheevaPlug power supplies that have failed, has anyone cataloged the components (capacitors) that tend to go bad?  My Sheeva is still running on its original PS, and as a preventative measure, I would not mind preemptively replacing the two or three caps that are prone to fail.  Anyone care to make a list?

[dattaway]

I believe you are essentially correct, Norbert.  I think 5V/2A is all that is theoretically needed, but 3A would give you a bit more of a safety margin, and is what I would prefer.  Just remember:  Red is +, Black is -.

With all the SheevaPlug power supplies that have failed, has anyone cataloged the components (capacitors) that tend to go bad?  My Sheeva is still running on its original PS, and as a preventative measure, I would not mind preemptively replacing the two or three caps that are prone to fail.  Anyone care to make a list?

From left to right: 1) 400V, 6.8uF, 2) 400V 22uF, 3) 1000uF, 10V....

Since these are filtering capacitors, substitutions can be made if the rated voltage exceeds the original.

edit: the one on the right is the most likely to fail.  When it vents, its capacitance drops to almost nothing.

[restamp]

Thanks, dattaway!  One more question:  I have a blown PS that a friend gave me that has some of the capacitors removed.  What is the value of the small electrolytic that is just to the right of the marking "400V 22uF" in your picture?  It's between the 2nd and 3rd one that you suggest replacing.  That one was removed and lost and I'd like to see if I can resurrect this PS.

[dattaway]

Thanks, dattaway!  One more question:  I have a blown PS that a friend gave me that has some of the capacitors removed.  What is the value of the small electrolytic that is just to the right of the marking "400V 22uF" in your picture?  It's between the 2nd and 3rd one that you suggest replacing.  That one was removed and lost and I'd like to see if I can resurrect this PS.

Unfortunately, I would have to take apart my running server which is hosting that picture to find out!  I did see from another picture on the internet and could make out a 22uF:

http://www.ronketti.org.uk/toasty.jpg

Not sure of the voltage, but it is on the high voltage side.  Might be 400 volts.  A higher voltage capacitor might be bigger, but will work fine.