Streaming from laptop to tv issue

[#1]

What happens if you try to play a fully downloaded video via your VGA cable?
You wouldn't need any functioning internet connection to do this.
Maybe you have a dodgy VGA connection / cable?
BTW I can play back HD videos from my hard disk (just!) using a Raspberry Pi "computer on a card" connected to a HDMI input on the tv.
The connection is made using NFS protocol and runs over a set of home plugs.
I strongly suspect that a pure wireless connection would be too slow.

[#2]

Hi Jeremy,
No problem playing downloaded video using my vga cable, as it doesn't require an internet connection to play back.  Because of surrounding hills and trees I cannot get live tv, either terrestrial or satellite satisfactorily, so streaming is the only option I have since analogue tv stopped.
                                                                                                                                                                                    Thanks Alex

[#3]

Oops, missed your later answer.  If you can log on to the router whilst the laptop is connected to the TV, see if the router thinks the internet connection is running or not.

[#4]

Hi RR,
Good to see your back on the case!  I like your methodical approach.
OK logged on to router and it was disconnected, tried to connect but the process hung.    A log on page appeared when I removed tv cable but then message when I tried to log on - authentication failed.  Had to log on again as if setting up the router!
                                                                Thanks  Alex

[#5]

Okay, as a working hypothesis I would say that when you connect your laptop to your TV or Hi-Fi then this causes a lot of high frequency 'noise' to find its way onto your phone line.  This tends to cause the router to drop the internet connection and then have trouble re-establishing it.  I presume the authentication failed because the noise corrupted the authentication data being transmitted.
The noise must start out in one of your bits of equipment, and I think the laptop itself must be the prime suspect.  It must then find its way onto the mains and thence onto the telephone wire.  Does anything nearby have a phone connection?  For example, TV connects to Sky box, Sky box connects to phone socket.  If not it must go via the mains.  Are your router, TV and laptop all on the same ring main?
Also, I have seen it suggested (though never tried it myself) that a radio tuned to the medium wave band (ideally running on batteries so it can be carried around) can help to track down noise issues.  Do you have one you can use?         

[#6]

I was thinking the same thing - about the noise making its way onto the phone line, and causing the drop of sync. I noted that this happens whenever the laptop has a wireless connection, but doesn't happen if there is no wifi connection.
Is it possible to repeat these tests while monitoring the SNRM levels in the modem? Either manually, or using a program like RouterStats?
The idea of using the medium-wave radio is good too. See near the end of this thread, "Sorry.....But I am sick to death with the problems on my line" for an example where someone is using the radio to listen to interference.

[#7]

Some of the numbers in http://en.wikipedia.org/wiki/Video_Graphics_Array look rather close to wifi frequencies...

[#8]

Thanks guys; I'm not an expert in this area so anybody else who want to chip in to help is most welcome.
Crawfordrainow, did you ever try my suggestion of trying the laptop running on battery only with the mains adaptor unplugged?

[#9]

This is very difficult to understand.
crawfordrainow do you have another PC?
A second PC could be used to monitor the routers status whilst the laptop is connected to the Sony TV.
I am not sure that the problem is interference to the ADSL signal on the 'phone line.
crawfordrainow reported in reply 39 that (as I understand it - no WiFi or ethernet connection between the laptop & router) the router internet LED remained on when the laptop was connected to the TV.
It appears that a LAN connection between the router & the laptop is required to knock out the routers internet LED.

[#10]

Yes, but I'm not sure the router LED light is a reliable indicator.  Whether or not the router maintains an internet connection, it appears the connection quality is not good enough for it to be usable.  But I agree that a second PC would come in very handy indeed.   

[#11]

Hi and thanks for your contributions,
I didn't think I would be able to try streaming to tv on battery because of the degraded state of the laptop battery.  However, I tried a lower power setting and gave it a whirl and guess what.... no problem, I can happily stream to tv, for a couple of minutes til the battery drains.  Interestingly the power adaptor is not original, that one failed so I bought a generic replacement, about a third the ptrice of a Toshiba.  Could this be the culprit?  I have not tried radio tracking for that reason. 
                                                                                              Alex

[#12]

Hi PS to last post,
      I tried plugging the laptop into an adjacent room that has a separate ring main, problm persisted exactly as before.    Alex

[#13]

Hi again,
Can anyone confirm that the fault is positively identified as the psu by the fact that I can stream from battery power please?  I do not want to replace it if that doesn't give a fix.
                                                      Thanks  Alex

[#14]

Was the psu a cheapie from hongkong off ebay
Any, 2 more tests i would do... Try your laptop at a mates house, and also if you can try a mates laptop, at your house. Use same vga cable in both tests. To be honest. I suspect its pretty conclusive given the test on battery, and you have tried a different socket...

[#15]

Hey, that's a big step forward.  Hooray.
The PSU on the laptop was my prime suspect, particularly as (we now learn) it was a replacement to your original one.  Have a look at http://en.wikipedia.org/wiki/Switched-mode_power_supply , in particular the 'Advantages and disadvantages' section.  So I think it is safe to invest in a replacement - just make sure you get a decent one.