Help - Diagnosing Ethernet dropouts

During the pre 0.4.0 experimental releases, I was experiencing ethernet dropouts, to the point that I had abandoned my beloved Rasplex in favour of a Plexconnected ATV3 (which is a good solution for European TV shows, but the lack of 24Hz output is a showstopper for US stuff). All of this after having "upgraded" my power supply to a proper 5V/1.2A (which I have tested with a multimeter).

With the latest release out, I tried again, and Rasplex is back on my TV.

Given that I have read success stories with high-bitrate 1080p movies (by high I mean > 10 Mbit/s, which were previously unwatchable), I applied dlanor's overclocking settings (thanks dlanor).

After booting, Rasplex picked up immediately my PMS, pre-cached everything and I proceeded to customise my settings.

As soon as I scrolled to "Movies", the PMS disappeared, then reappeared one second later, and so on..

Going to the Connections section of the rasplex settings confirmed my suspicions. The ethernet connection was flashing every second.

So I decided to overvolt by 2 instead of 4. The dropouts were even more frequent.

Disabling overvolting prevented the Pi to boot (black screen after the Rasplex logo).

Now, I set it to 1. Dropouts are less frequent, but I actually managed to start playback once.

While I am fully aware that I am treading on thin ice, my question is: why does the dropout always occur when browsing the library (most of the times when I scroll to Movies or TV Shows without selecting the section) and never during playback?

Is there something I can do to better diagnose the problem?

Thanks a lot.

maybe check the debug logs .?

Thanks Longchair, I wasn't sure if logs could be helpful since it seems that this happens at a lower level. Here are the logs, the event occurred at around 14:29.

Plex HT Log

http://pastebin.com/9QGfyT4a

Varlog - lots of network stuff here

http://pastebin.com/5yPHqcXD

Kernel Log

http://pastebin.com/SVbTEH5f

Thanks for your help!

Based on my experience, if you use a power source that doesn't supply enough power, one of the first to drop will be the ethernet. (Then raspberry will reboot :D)

Try using a different (1.5-2Amp) power source and see if it makes any difference. Yes, I know it's way above what it  should use, but at least you rule out one cause.

As for why "why does the dropout always occur when browsing the library [...] and never during playback?" that might have to do with the buffering. Maybe. 

Give it a try and please let us know the results. 

Based on my experience, if you use a power source that doesn't supply enough power, one of the first to drop will be the ethernet. (Then raspberry will reboot :D)

Try using a different (1.5-2Amp) power source and see if it makes any difference. Yes, I know it's way above what it  should use, but at least you rule out one cause.

I'm picking up a new 2A adapter this afternoon and will report back! I tried with an iPad adapter but I soon realised its output was 5.1V instead of 5. Instant dropouts occurred.

No luck with a 5V/2A adapter.

Tried different over voltage settings,  removed the custom overclocking, reset to the standard config.txt, changed ethernet cables, plugged the adapter straight into the wall instead of a strip, etc...

I think my unit must be faulty since I am apparently the only one with these problems.

I will go back to Plexconnect and patiently wait for Cubox-i support.

No luck with a 5V/2A adapter.

Tried different over voltage settings,  removed the custom overclocking, reset to the standard config.txt, changed ethernet cables, plugged the adapter straight into the wall instead of a strip, etc...

I think my unit must be faulty since I am apparently the only one with these problems.

I will go back to Plexconnect and patiently wait for Cubox-i support.

Sorry to hear it doesn't work for you.  I know you sound like you gave up, but... Even if it says 5V/2A some adaptors don't deliver what they promise... Any way for you to measure the real voltage (use P1 & P1 testing points on the raspberry pi board)?

Then again, you might be right and have a faulty unit... 

Thanks for your tips MoonshineSG, I did some more investigating and I think I found the culprit, the Pi's F3 polyfuse.

Testing the TP1&TP2 pins reports ~4.5V, which is terrible according to http://elinux.org/R-Pi_Troubleshooting#Troubleshooting_power_problems.

However, testing the micro USB cable directly reports a steady 5V. Testing power going in the F3 fuse is 4.9V but going out there is a drop of half a Volt, so I guess my fuse has too much resistance.

Apparently I'm not the only one, this is an extract from a post on the Pi forums.

Well I was wrong about the adapter, turns out it's the F3 fuse...  .

Thanks to the tip from thsBavR10 I ordered new F3 fuse from newark. What a difference.
My old fuse had a resistance of 1 ohm and my TP1-TP2 voltage was 4.5-4.6V
The new fuse has a resistance of 0.1 ohm and my voltage is now 5.03V (the adapter provides 5.25VDC)

So, if you have a lower than normal voltage on TP1-TP2 (less than 4.8V) or are having weird problems with your PI, check your F3 fuse with an ohmeter (with power off).

In my case though, I'm a total n00b as far as soldering irons are concerned. So I guess I will live with it :)

Anyway, I flashed an old version of Rasplex, 0.1.38. With the 2.4A adapter I get dropouts, but with the 1.2A everything works fine. Yes it is slow but at least I can playback stuff with it. The recent optimisations done to PHT probably require more power than my unit is getting.

At least now I know slightly more about electricity than a few hours before!

When you have a chance, could you tell me your voltage reading out of the F3 fuse?

You could always try to deliver power through one of the USB ports. If you search the internet, you will find that this is possible as well. In that case (if I remember correctly), power does not pass the fuse - in your case that might solve the problem.

Thanks for your tips MoonshineSG, I did some more investigating and I think I found the culprit, the Pi's F3 polyfuse.

Testing the TP1&TP2 pins reports ~4.5V, which is terrible according to http://elinux.org/R-Pi_Troubleshooting#Troubleshooting_power_problems.

However, testing the micro USB cable directly reports a steady 5V. Testing power going in the F3 fuse is 4.9V but going out there is a drop of half a Volt, so I guess my fuse has too much resistance.

Apparently I'm not the only one, this is an extract from a post on the Pi forums.

In my case though, I'm a total n00b as far as soldering irons are concerned. So I guess I will live with it :)

Anyway, I flashed an old version of Rasplex, 0.1.38. With the 2.4A adapter I get dropouts, but with the 1.2A everything works fine. Yes it is slow but at least I can playback stuff with it. The recent optimisations done to PHT probably require more power than my unit is getting.

At least now I know slightly more about electricity than a few hours before!

When you have a chance, could you tell me your voltage reading out of the F3 fuse?

mine reads 4.96V drop to  4.83V