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Author Topic: USB Weirdness  (Read 2205 times)
adamf
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« on: August 18, 2010, 04:08:31 PM »

I have the std SheevaPlug & it's been running like a champ for a long while (24X7).

It has an external 3.5 hdd (independantly powered) via a (powered) USB hub.

Suddenly...in the last week...If I plug anything into USB  (even just the hub if on boot though if post boot just the hub is OK) the plug keeps rebooting.


If I then unplug the USB hub & restart the plug starts OK but then the date is always reset to Sat Nov  8  1947

At this point not a lot works (e.g. dns etc because obviously the date is so far off ) but I can get on using ssh & reset the date & then everything works once more.

Plug in the hub (just the hub)  & everything stays working.....plug in the disk into the hub (or anything else USB e.g. my LIRC USB infrared adapter) &...... pow back to rebooting.....

Any ideas?

Adam
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cjm
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« Reply #1 on: August 18, 2010, 11:32:28 PM »

Could be the power supply. Plugging in the USB hub will draw more power, even if its only a little as your hub has its own power supply. If this is the case, the plug should stop booting even without the hub attached pretty soon as the power supply gets worse quickly once the capacitors have lost their electrolyte. NewIT sells replacement power supplies for around 10 bucks but shipping outside of Europe is expensive. Or you could hook up an external 5V power supply with around 10-15W.

Could be something else, of course, but it seems the original power supply will always fail sooner or later.

BTW, I've seen this kind of failure on other devices as well. My NSLU2's power supply failed the same way after one year of uptime. Switching power supplies require special low-ESR capacitors with high temperature tolerance but for some reason it seems many manufacturers want to save the few cents those capacitors would cost extra...

Thanks,
--Christian
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adamf
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« Reply #2 on: August 19, 2010, 01:49:41 AM »

Could be the power supply. Plugging in the USB hub will draw more power, even if its only a little as your hub has its own power supply. If this is the case, the plug should stop booting even without the hub attached pretty soon as the power supply gets worse quickly once the capacitors have lost their electrolyte. NewIT sells replacement power supplies for around 10 bucks but shipping outside of Europe is expensive. Or you could hook up an external 5V power supply with around 10-15W.

Ahhh...OK

A) Is there a wiring diagram etc which says solder A to B etc?
B) I have a number of such beasties (a large drawer full of wallwarts) & I am now (having done a quick look on the forum wrt "power supply problems") wondering whether the wall wart is the answer as they normally outlast the electronics they power (hence the large drawer full).

Which do people recommend the external wall wart or the replacement PSU?

For one thing is the PSU daughter board mounted ergo connect external psu & remove internal psu thus increasing airflow/cooling etc?

Could be something else, of course, but it seems the original power supply will always fail sooner or later.

BTW, I've seen this kind of failure on other devices as well. My NSLU2's power supply failed the same way after one year of uptime. Switching power supplies require special low-ESR capacitors with high temperature tolerance but for some reason it seems many manufacturers want to save the few cents those capacitors would cost extra...

Thanks,
--Christian

Crikey I thought this died out in the late 90'es when pc mobo's had this problem wrt capacitors.....

Adam
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tylernt
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« Reply #3 on: August 19, 2010, 09:21:31 AM »

Crikey I thought this died out in the late 90'es when pc mobo's had this problem wrt capacitors.....
The capacitors in the Sheeva PS aren't defective, they are merely under-specified -- used for a purpose they were never designed to endure.

You may wish to open the cover on your Sheeva and check the RTC clock battery voltage. The fact that you have date problems makes me think the battery may have an issue.
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cjm
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« Reply #4 on: August 20, 2010, 01:24:08 AM »

As to the wiring diagram: Just hook up a 5V 2-3A PSU to the thin cables coming from the orignal power supply. Red is plus. There are other threads here on the forum with pictures and detailed instructions -- just seach for "dead" Wink

BTW, the power supply should of course be regulated. I would recommend to check the voltage with a meter to make sure it's 5V +- 0.1V both when idle and when connected to the plug to be on the safe side.

Thanks,
--Christian
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