Greetings and project help

Discussion in 'The Projects Forum' started by JohhnyPaul, Aug 30, 2009.

  1. JohhnyPaul

    Thread Starter New Member

    Aug 30, 2009
    3
    0
    Well where do I start? I'm not the best with electronics, but I'm learning as I go. My TV blew a fuse, and when I replaced the fuse, for some reason the only button that works on the tv is the power button, none of the channel, volume or tv/av buttons work. The other issue is the Automatic timer is messed up, at first, the tv would automatically shut off when turned on (kind of like if certain components were overheating), but I must of hit somthing because now it does the opposite (it stays on, but when you turn it off it goes F this and turns itself back on.)

    I'm wondering if it might be a bad idea to start turning the potentiometers inside to see what they do or maybe if I can post some pictures of the circuits and someone can give me some pointers?

    Its an LXI tv (which was a sears in house brand, which uses tons of different parts, so technically its a sanyo tv based on the universal remote code).

    I'm looking forward to talking to most of you, but if anyone can help let me know. thanks alot.
     
  2. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
    A short circuit has occurred in your TV for which reasons are not obvious from your description resulting in the main control board not recieving power or some circuit malfunction. Any idea of what happened before this fuse blew?

    You could open up the TV and just look around below the circuit board if something has burnt or liquid has entered. However do NOT touch the board unless you know what you are doing. The TV has a flyback transformer with a voltage of 33Kv even when switched off stored in capacitors and the flyback. It must be discharged before you handle a TV board. So better call a technician than getting killed. Remember, this thing is not like the one giving a shock hazard, it is a death hazard.
     
  3. JohhnyPaul

    Thread Starter New Member

    Aug 30, 2009
    3
    0
    I appreciate the warning. I make it a habit to not touch anything that looks even remotly dangerous, which is why I'm asking if it would be a good idea to mess with some of the potentiometers near the audio source, not sure if tampering with them will cause any excessive runoff and blow up something else. I tend to stay clear of the bulb, the suctioncup deal (so basically anything hanging off of the tube) and anything with exposed copper wire.

    The fuse blew when one of the neighborhood kids tripped over the powercord while the tv was on. I did some observation, and on the back of the bulb there was a thick black liquid about the circuit (not sure if it was there before the fuse blew, however, I doubt that has anything to do with the controls, more or less the dark and runny picture, either way, Its too close to the bulb, so I ain't touching it. Also, one of the wires running by the control pannel (not directly from) which is two wires colored white and pink, has a few dark spots on them, not sure if that has anything to do with it either. I'll try and get some pictures together.

    I apologize if following my sentences are difficult, I have trouble on that end. Thanks again for the advice so far.
     
  4. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
    The potentiometers are only to be adjusted with the necessary test equipment, like a function generator or pattern generator. Simply turning it would never make a non functional tv back to normal. It is designed only for fine adjustments, not like a fan regulator to completely change everything. If you mess with it, then after a real service to the original problem, the tv would take a lot of time to be calibrated back to normal by the service men and maybe wouldnt even reach the original factory settings.

    Tampering with them wouldn't blow up anything, thats not a problem, only you change the fine adjustments which will result in poor AV clarity. The bulb you say is the picture tube. The suction cup you reffered to is the High voltage conenction line. Just observe the wire to the board, you can see a small 'box' , that is the HV flyback transformer.

    [​IMG]

    The thick black liquid might be latex laquer, used to seat and seal the picture tube safely without shaking. If it is all over on the board, then something might have burned. There are ways to discharge the devices, but shouldnt be tried by unauthorized personnel. You Tv might only have some minor problems like a burnt wire or resistor, but depending upon the make and model, may even be a burnt chip. Get someone to service it at your home, you can see the whole procedure yourself rather than sending it off to the service centre.
     
  5. JohhnyPaul

    Thread Starter New Member

    Aug 30, 2009
    3
    0
    Ah yes, I've seen that little box (Its actually kind of large in this tv). I'm Glad you answered my questions about the potentiometers, I really wasn't looking forward to messing with them.

    I'm definatly going to get someone to service it here at the house. It was a pain enough to get it in here. Thanks for clairifying all the terms and such for me. Hopefully I'll get this fixed soon.
     
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