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1  Hardware and U-Boot firmware / Hardware / Re: Is my sheevaplug dead ??? on: March 05, 2010, 01:16:06 AM
SuperPat has some really important information in the thread on USB power supply problems (http://plugcomputer.org/plugforum/index.php?topic=1347.msg8339#msg8339).

Please Read It before you attempt any modifications on your power supply! Pay particular attention to the warning:

Quote
WARNING....  MAINS SWITCHING POWER SUPPLIES, ESPECIALLY THE FILTER CAPACITORS CAN HAVE SEVERAL HUNDRED VOLTS ACROSS THEM EVEN AFTER THE SHEEVAPLUG IS DISCONNECTED FROM THE MAINS. THEY CAN  KILL OR GIVE YOU A NASTY FLASH BURN.  OBSERVE ALL NORMAL HIGH VOLTAGE SAFETY PRECAUTIONS WHEN WORKING ON MAINS SWITCHERS. 

If you don't know the normal HV safety rules then you should not be into a mains switcher!

I would add that it is possible for the capacitors to hold this dangerous charge for weeks or even months.  Don't assume that it is safe simply because it has been unplugged over night or over the weekend. In fact, I wouldn't recommend opening the silver box.

Upon re-reading my posts, I realize I posted without including the warnings I should have. I apologize for unintentionally putting anyone at risk. Please use care.

The other thing SuperPat suggests is that a 5V @ 3A to 4A  external power supply may be necessary as the Sheeva can draw as much as 2A at peak load. So far, my Sheevaplug is still working well but I defer to his judgement and knowledge.

2  Hardware and U-Boot firmware / Hardware / Re: Is my sheevaplug dead ??? on: March 04, 2010, 11:48:25 PM
I think the bare plug draws somewhere around 850mA to 1A without load. Adding a wireless adapter or USB flash drive might bump that up to 1100mA or so. There are some AC / USB adapters that provide right around 1A but it doesn't really give you much headroom. The Gigaware is only a suggestion. If you keep old parts around, you might find other 5V sources. If you have any broken (powered) USB hubs around, many of those seem to be 5V @ approximately 2500mA to 3000 mA.

The plug will only draw the power it needs so the 2A is only to make sure I'm not stressing this power supply, too.

I would second not using an unpowered USB hard drive. I was using an unpowered 2.5" SSD. I thought I might get away with that since it wouldn't have to spin up. Interestingly, I almost always use a powered hub but just neglected to hook it up this week when I was moving it and upgrading some software (it had been running 24/7 since September). So, I'm just guessing but I think it's ultimately a heat issue that is weakening and killing the power supply.
3  Hardware and U-Boot firmware / Hardware / Re: Is my sheevaplug dead ??? on: March 03, 2010, 11:15:28 PM
Okay, I had the same problem. Green LED kept blinking approximately every second. Opened it up -- same brown crap everywhere in the power supply.

There is a fairly simple fix. Dump the power supply. Cut off the plug that connects to the main board. Then go down to "The Shack" or somewhere similar and get a Gigaware Gaming AC Power Adapter. It's about $14 or $15.  It provides an output of 5V, 2A which gives you a little clearance over what the plug usually draws -- depending on what you have plugged into it, of course.

I also purchased matching male and female DC power connectors. I think I used size M. If you unscrew the figure 8 plug connector, your new power receptacle will fit in this spot (on either side of the figure Cool. Mind the gap.

Now you have a choice. If you want to keep some of the options for the Gigaware Power Adapter, just cut off one of the plugs. Otherwise, cut them all off just before the junction where they all split off. Now just wire up your new DC power connector plug to the Gigaware power adapter and the other receptacle to the little plug you cut off the original power supply. If you wired it up without wiring it backwards it should power up nicely when you plug it in. Now just put it back together and enjoy your plug powered plug.

It's a good idea to check and re-check your connections with a voltmeter before ever connecting the new power supply to the Sheeva. As my father always says, "One is negative and one is positive. I'm just not positive which one is negative."

My Sheeva is up and running again and acting much more stable than it did just before it stopped working. The other nice thing is that it is so much cooler without the heat from the internal power supply.

Hope this helps. Let me know if you have any questions.
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