lesliew
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Joined: Sun Jan 22, 2012 5:14 pm
Location: Melbourne, Florida

Maybe time for an RMA ?

Wed May 30, 2012 2:04 am

OK so I've reached the conclusion that my Pi is faulty. Below is a list of power supplies that I've tried.

BTW they all power the Pi, but in most cases the Pi crashes, (i.e screen goes blank PWR & OK lights stay lit) after around 2 minutes, the Scosche 4 Port USB works the best I managed to get about 30 minutes use a few times before the Pi shut down. The worse culprits are the Nokia AC-10U Chargers which cause a kernel panic before I even get a login prompt.

I had a lot of these charges/Hubs already, but in the last week did buy a $20 Belkin Kindle Charger and in desperation bought 2 cheap Nokia charges of ebay, so its not surprising they didn't work but I've reached the point where I don't think the power supplies (with the exception of the Nokia's) are at fault anymore.

This is the list of power supplies that I have tried

Scosche 4 port USB Charger QUBSH , 5v @ 2A
Apple iPhone 4S charger A1265, 5v @ 1A
Blackberry Charger PSM04A, 5v @ 750mA
Belkin Kindle charger F5L077, 5v @ 1A
Nokia AC10U charger, 5v @ 1.2A
Dlink 7 Port Hub, DUB-H7, 5v @ 3A
Belkin 4 Port Hub, F5U-404, 5v @ 3A
USB Hub in Dell U3011 Monitor

HP TouchPad Charger, 5v @ 2A - borrowed
Samsung Infuse 4G Android Charger - borrowed

I've also tried Patriot, Sandisk, Wintec, PNY, GSkill, SDCards & used the latest kernel via rpi-update

My Pi was from the initial production run, 2nd batch - 1213.

The only problem with requesting an RMA request is that I have to return it to farnell UK, from USA

Any thoughts ?, or guaranteed to work power supplies I can try! - Need to work in US

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johnbeetem
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Re: Maybe time for an RMA ?

Wed May 30, 2012 4:16 am

There are two other components that can cause this sort of problem. The first is the micro USB cable: some of these have very thin wires that have enough voltage drop to cause RasPi to fail after a while. The other is RasPi's polyfuse F3. As RasPi warms up the resistance of F3 increases and if the power supply or micro USB cable is marginal then failure can occur. To investigate these problems you'll probably need a multi-meter.

For more information, check out the RasPi wiki: http://elinux.org/Rpi_Hardware#Power_Supply_Problems and http://elinux.org/R-Pi_Troubleshooting.

For polyfuse issues, search for "polyfuse" in the Forum search or the front page Google search.

The problem could be something else, but these are good starting points.

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rurwin
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Re: Maybe time for an RMA ?

Wed May 30, 2012 6:27 am

Maybe there is someone around you with a RaspPi that you can swap gear with, just to check? It would be horrible to do an international RMA and get the same problems again.

The two power leads I trust are the HTC and Nokia leads that came with my last two phones. They are both quite stiff.

RMW5
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Re: Maybe time for an RMA ?

Wed May 30, 2012 2:27 pm

I have my doubts about some of these phone chargers that people are using because I don't think they were designed to be as stable as the R-Pi requires.

I was having similar problems and tried a variety of adapters and the voltage measurements across TP1/TP2 were around the 4.6V mark even with all the USB attachments on a powered hub.

The power supply to the generic powered USB hub (model is UH-174 and is available under many brands) was actually putting out about 4.8V, so I went and bought a 5V/2.2A regulated power supply - around £15/$22 - a bit pricey for a "$25 device". That made some improvements, but the power supply did not come with a micro USB attachment, so I powered the front end of the R-Pi with a short USB lead from the hub, and that setup gives as near as dammit 5V across TP1/TP2 and no problems so far.

lesliew
Posts: 29
Joined: Sun Jan 22, 2012 5:14 pm
Location: Melbourne, Florida

Re: Maybe time for an RMA ?

Thu Jun 07, 2012 1:29 am

After taking all of those points on board and reading lots of other similar posts, I'm still of the same conclusion that my Pi is not functioning correctly. It took a week or so to order various bits and pieces but below are my results.

Not that I didn't have enough cables already with all those power supplies that I already tested, but I went out and purchased a couple of the beefiest micro usb cables I could find $22 for 1 usb cable, got to be a joke. Tests appeared to start out well but I think that I just wanted it to work too much. To cut a long story short no real difference with the new cables I tried.

Then I went about measuring the voltage across TP1/TP2 and to be quite honest with the chargers/hubs I measured they read anywhere between, 4.76v - 4.84v with ethernet and keyboard connected, which from further reading seems to be at the low end of spec. I also tried the Pi without usb/ethernet/hdmi connected and with the peripherals connected to a powered hub.

Next step to totally rule out power was to purchase a regulated DC power supply. Not wanting to go too overboard I got this one http://www.amazon.com/dp/B000CSQK5E/ref ... C_ST1_dp_1

This allowed be to keep a constant voltage across TP1/TP2 and I tried every increment between 4.75 - 5.25v, with the maximum current set at 1100mA. Basically in every case I had the exact same result with the screen going blank and power and OK lights staying lit but essentially the Pi powered down shortly (sometimes upto 20 mins) after getting the logon prompt.

Always willing to try other suggestions but I'm running out of time.

Whats the normal period to request an RMA ?, Wife and kids are on a plane to England next Wednesday, so its the best time for me to send it back.

SliceOpi
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Joined: Fri Mar 30, 2012 6:05 am

Re: Maybe time for an RMA ?

Thu Jun 07, 2012 5:42 am

I am looking at the terms and conditions at newark as I type this because I am having exactly the same issues as you are, actually...it's been driving me crazy! I may be frustrated with this one, but it really does seem to be a random defect- there are just too many people happily using this now for the problems we're having to be common. (I hope...)
Anyway, it says at newark.com that we have 60 days from the date of the original invoice date...but then it says that "warranty related return procedures will be determined by the manufacturer's warranty policy for the applicable product. Please contact your Newark/element14 Customer Service Representative for details." So...I guess I have to call them either way and get the RMA number they require before any returns are made anyway.
The only concern I have is whether or not they will have any stock to replace mine with, since they're pretty exclusive still. I suppose I'll find out when I call.
Good luck to you.

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rurwin
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Re: Maybe time for an RMA ?

Thu Jun 07, 2012 6:33 am

They are holding stock to handle returns. You will get replacements in good time.

It does sound like you have a bad one, lesliew. If the TP1/2 voltage is over 4.75V then the power supply and F3 are good. In fact I found mine working at a much lower voltage than that (4.4V IIRC) without complaint.

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