1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Other Bloody odd cause of computer problem! :D

Discussion in 'General' started by jewelie, 5 May 2016.

  1. jewelie

    jewelie Ancient geek, newbie to BT

    Joined:
    3 Jun 2015
    Posts:
    50
    Likes Received:
    4
    TL;DR Erratic performance on laptop trackpad when plugged in with original charger solved by disconnecting house from communal UHF TV aerial! :eyebrow:

    Hi folks! :)

    For the last year the trackpad on our Dell Inspiron N5030 has been intermittently erratic. Fed up with it, I decided to try and fix it; I assumed it was the trackpad or the cabling between it and the laptop that was faulty, or perhaps I'd broken something when upgrading it at some point (goodness, a CPU upgrade and an SSD can make all the difference!)

    I did some Googling for parts and also reports of similar problems and turned up LOTS of results about dodgy 3rd party laptop PSUs emitting RFI that's the route of the problem... so I did some experimenting and yes with the PSU connected there's problems, on just battery it's fine, and the problem also goes when the PSU is connected if I hold a shielded part of the laptop. However, this is the original PSU, not a WunHungLo[tm] and I just didn't buy it being the PSU itself in this case...

    ...so did some more investigating, just to check...

    The problem only occurred when connected to around half the sockets on a particular ring main. It didn't matter where the laptop + PSU were, just which sockets on the ring main it was connected to (tested through elemination using extension leads to compare the problem between different sockets with the laptop & PSU in the same place - then moving the laptop + PSU around and repeating the test.)

    Two sockets on same ring main behaving differently? **BUGGER** Must be iffy connection on ring main. :worried:

    Where? Obvious first guess is where one of the two-where-one-goes dual gang sockets were installed (one by an "electrician", one by my Dad who used to be qualified to do such things, and two by me who's not qualified to do that sort of thing but therefore is REALLY careful to do the job as properly as I can.)

    Some basic tests later and it seems the continuity measured between sockets around the mains ring is fine (as fine as I am able ascertain with the equipment I have.) So, not the mains ring! This is getting odder and odder... perhaps it's RFI from other devices propagating part way around the ring? All devices turned off. Nope, that's not eliminated it.

    Hmmmm..... phoned Dad, who suggests to make sure to physically disconnect everything from the mains plugs, including 4-way adapters etc.

    So, off we went, disconnecting absolutely everything from sockets, all sockets (including the landline/broadband and the communal aerial.)

    AH-HA! GONE! :clap:

    Cool. So we're getting there! Now to start reconnecting things, one by one, slowly slowy catchy monkey...

    ...GOTCHA! :rock:

    With all equipment physically turned off, except for the laptop+PSU, and the communal aerial attached to any piece of (turned off) equipment, we get an RFI problem that messes up the laptop trackpad when the laptop is connected to around half the sockets on the ring main (those nearest the device that's connected to the communal aerial and plugged in but not turned on.) It seems it's NOT travelling "through the air" though but travelling from the communal aerial socket, through the turned off TV, into the mains, and going part way around the ring, and is strong enough to travel a fair way down the extension, through original laptop PSU and bugger up a laptop trackpad!

    :jawdrop: :eyebrow:

    SO....

    Any thoughts on this mystery RFI from the communal aerial and what I could do about it?

    1. Could it be the 4G mobile masts that have been introduced here? Bloody stupidly they're pumping out the new 4G signal slap-bang in the middle of what used to be used for analogue TV here until recently (unsurprisingly there's some expectations of some problems in some areas and there's a service to supply free filtering equipment.)
    2. We've just had two pieces of equipment fail early, one high quality ATX PC PSU (general consensus of opinion on here was a premature MOV failure) and now a printer (unknown electrical problem - manufacturer error codes can be bloody useless at times.) Any possibility of a connection to the above that I should be concerned about?
    3. Any thoughts how I could investigate further? I don't have a scope, or even decent meters.
    4. Any ideas how I could solve it? Somehow decoupling from the communal aerial feed, a bandpass filter perhaps?

    Warm Regards
    Julie
    x
     
  2. asura

    asura jack of all trades

    Joined:
    22 Apr 2009
    Posts:
    1,747
    Likes Received:
    78
    Remain completely disconnected from the communal areal and buy a mini one to sit on a window cill?
     
  3. jewelie

    jewelie Ancient geek, newbie to BT

    Joined:
    3 Jun 2015
    Posts:
    50
    Likes Received:
    4
    Not viable, unfortunately. Ground floor flat in a rubbish signal area. :( I've tried, many times! Thanks for making a suggestion though. :)

    I'm waiting on feedback from a manufacturer, but there's an inline aerial filter that seems to be genuinely bandpass and should filter out DC, low frequency AC, 4G, Tetra and everything else not TV. Our TV signals go from channel 31 to 57, it's really hard to find a bandpass filter that covers those.
     
  4. jewelie

    jewelie Ancient geek, newbie to BT

    Joined:
    3 Jun 2015
    Posts:
    50
    Likes Received:
    4
    Eventually discovered the aerial system was emitting enormous RFI across MW radio (wiping MW radio out.)

    Engineer came out, fixed aerial system (it predated 4G etc and he reckons it was a 4G issue.)

    Problem with trackpad gone.

    :)
     

Share This Page