(2014-06-29, 17:35)Bosse_B Wrote: Right, but as a new user of a Pi with the intention to just set up XBMC and get it configured I suspect that the capacity for analysis of the problem down to finding out that the cause is the darned cable is probably beyond the ordinary user.
I am a retired electronics and software engineer (MScEE) so I have at least the equipment needed to trace this down, but it was not the first thing I thought about, I must say.
I have an electronics background too (although not currently practicing in my day job...) so I have a good understanding of the voltage drop issues the Pi suffers from, but it's very hard to convince people sometimes that their random crash/freeze/loss of Ethernet etc really, honestly, probably is a voltage drop issue, and that until they rule that out by actually measuring it, they're running around in circles looking for a software "fix" that doesn't exist.
It doesn't matter that the label on their power adaptor says 5v 1amp, rarely for a USB charger does that mean it is still actually putting out 5v at 1amp, (they're poorly regulated, if at all) and then you have issues with the cable like you had, or a faulty polyfuse, or a combination of the three.
A high percentage of the problems reported here and over in the raspbmc forum (I'd say 60%) which often seem bizarre and inscrutable are almost certainly just power issues.
Those people that take the advice to check the voltage more often than not find their power adaptors aren't up to snuff, fix the voltage drop problem and the problems they were having disappear. But there are a significant percentage that won't accept the advice to check the voltage - "I have a 5v 2amp supply, it should be fine", "it was working fine with Frodo so it can't be the power supply" etc...despite the fact that us regulars see the same problems reported over and over and they are nearly always proven to be power related...
With bad power Pi's are woefully unstable, with good power they are remarkably stable. I've had almost zero trouble with mine, it runs 24/7 for weeks on end with a 1000Mhz overclock without a reboot, its had all kinds of abuse while doing test/development work and it is as stable as can be, so they can be very good.
Quote:I have now read the thread DBMandrake pointed to including its follow-up links and I do hope Farnell heeds the advice and makes sure that the power supply "designed for" the Pi really also has a proper power cable in the package....
I link to that page for any possible voltage related issues because it neatly explains the issue and how test for it - anyone with access to a multimeter can follow the instructions even without an electronics background. Not everyone has a multimeter of course but a cheap one can be had for almost nothing, considering how cheap the Pi is compared to other HTPC systems its not a huge burden to get one to help troubleshoot problems.
IMHO the Raspberry Pi foundation made a serious design error by leaving out the 5 volt regulator (and DC barrel jack) that the Alpha boards had in an effort to cut costs and keep it below their arbitrary $35 target price, now we have millions of Raspberry Pi's out there that are hypercritical about their power adaptors and the Pi has a bit of a reputation for being unstable because of it.
That's what we have to work with though - use a good power supply and cable and it does work very well.