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CRT TVs keep blowing up.

Discussion in 'General Electronics Discussion' started by echamings, Sep 6, 2011.

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  1. echamings

    echamings

    1
    0
    Sep 6, 2011
    Hi all,

    I'm not a regular here but I don't really know where to ask. I hope perhaps someone can help!

    Scene:
    We have an old house that we rent form a landlord, the electrics have always been a little bit... fruity. They will go off quite by random, and we have to put the RCD switch back on to power the house again. Weve had electricians round and they can find nothing wrong, no ground faults, no breaks in the wires etc.. it has been blamed on our equipment overloading the RCD but who knows,

    Anyway, we can cope with the electricty problems for now, the cutout is leaking bitchumen and will be replaced, following that the meter is due to be replaced, perhaps one of those will fix the problem, or we can continue testing anyway.

    So my house is also a graveyard to CRT Tvs. We have about 6 old tellies in the basement that have spent some time here and then given up. Two have gone in the last week!

    It appears the tube goes in each, power comes on, but the screen stays blank.

    They appear to be the only appliance damaged by the supply here.

    My main question is: Is there anything we can buy to sit between the socket and the tv to protect them further?

    If anyone has any thoughts on the supply issues (that get worse in the wet) then I'd listen too, but dont worry if not.

    Thanks for reading!

    Ewan
     
  2. daddles

    daddles

    443
    3
    Jun 10, 2011
    What makes you think it's the power supply that is killing the TVs? I mean, what physical evidence do you have? Do you know the actual failure mode of the TVs? The reason I'm asking is not to be contrary; it's just that I've been troubleshooting things for a long time and one of the precepts is to know you're working on the right problem. Unless you know how each TV failed, a careful troubleshooter would be loath to blame it on something without real evidence. NOTE: I'm also not saying it's NOT your power supply, but until you have real evidence, you don't want to rule out other causes. What if it was something a bit unusual, like a cat peeing on the back of the TV, causing a short?

    The only way to pin it for sure on the power supply is to put a monitoring device on the line and watch what happens over a significant period of time. Alas, this is equipment a homeowner won't have and likely couldn't afford. I don't have one of the power monitoring devices made by e.g. Fluke (they cost thousands of dollars), but I would put my digital oscilloscope on the line and use it to monitor for transient events/weird behavior. Modern digital scopes have persistence that you can turn on and it will capture the envelope of the signal over time, telling you e.g. if there was a transient.

    If you hypothesize that it is the line power, then there are devices you can put on the line to reduce/minimize the effects of power changes. If it was me, I'd start with an isolation transformer that would probably do a bit of filtering of short transients, mainly because I have one sitting next to me. :p I also have a ferroresonant transformer that I could try if I felt it was voltage variations causing the problem. Other more experienced folks here will also likely have some other recommendations.
     
  3. davelectronic

    davelectronic

    1,087
    12
    Dec 13, 2010
    CRT break downs

    Hi echamings.
    We had similar problems with cut outs, but it was found eventually, are electric cooker had an earth fault, i tried to find it, no luck, the engineer attending said good luck i could be there all day fault finding the cooker.

    Any way line spikes and transients are not uncommon, sometimes nothing in the house, have neighbors had any problems ? are you 240v or 110v ? there might be a common problem on that grid line. something drawing very large currents and voltage, Drug houses cannabis is one example, not you, they still pull in from one of the phases, high power lamps ventilation etc.

    In the mean time you can purchase an adapter, single or multi out let, these clamp line spikes and transients, some are designed to protect sensitive, equipment, you could build something, but unless your 100% clued up on mains procedure, i would opt for a retail unit, there not that expensive. Dave. :)
     
  4. shrtrnd

    shrtrnd

    3,712
    468
    Jan 15, 2010
    You've already got advice on power problems. Here's something else to think about:
    Where I lived in the summer, the basement was a high humidity environment.
    If the TV innards are moist, and you fire-up a 300watt CRT television, you can blow
    some circuits. I know I did.
    Just something to look at when you're considering possible problems.
     
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