Fixed my PC monitor :-)

Discussion in 'Just Talk' started by Allsorts, Aug 15, 2018.

  1. Allsorts

    Allsorts Well-Known Member

    Which is a 37" Samsung TV...

    Which would, more and more often, refuse to come on.

    Isn't the internet wonderful? A quick Google pointed to the power supply board and a likely dodgy capacitor. Sadly the miscreant didn't expose itself with a knowing bulge, so I replaced all 13.

    Astonishing how little is inside a modern LCD TV - only two main boards, and the PSU one was larger and seemingly more loaded than the actual 'TV' board.
     
    Last edited: Aug 15, 2018
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  2. btiw2

    btiw2 Well-Known Member

    I bet that felt good. I find there’s something incredibly satisfying about fixing electronic devices.

    Firstly, you can’t really fail. If it was knackered before you start, then you can’t make it worse. Failure doesn’t move you backwards. It’s not like you’ll flood the house if it goes wrong.

    Secondly, those devices are like magic. I’m not smart enough to work my away around a circuit board and say “oh yes, the A5663 chip will process that signal and output a voltage on pin 7”, they’re mysterious to me, but when you replace bits and the thing starts working again - that’s like magic too.

    Thirdly, solder smells nice. It’s probably the flux.

    Was it very fiddly?
     
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  3. Bob Rathbone

    Bob Rathbone Well-Known Member

    With most electronic devices all of the fancy diagnostic kit is fine for the obscure 10% of faults, the other 90% will be found with a simple visual inspection and a multimeter. Power supply faults are most common as this is where the current and heat is most concentrated. I fixed a PC monitor on a jukebox last week, the fluorescent back light was not working, I took out the lamp transformers and replaced the lamps with 2 strips of the flexible stick on LED's and fed them from the 12V supply. Works fine.
     
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  4. Allsorts

    Allsorts Well-Known Member

    Not fiddly at all - these were big proper capacitors :). None of this surface-mounted malarkey.

    Took me right back to my childhood - mmmmm, these toxic flux and lead vapours (never did me any harm...).

    I over-sized every one I could for voltage rating tobesuretobesure, so a couple had to lay peacefully on their sides rather than upski as before.

    It is magic indeed.
     
  5. Allsorts

    Allsorts Well-Known Member

    "A PC monitor on a jukebox"? Surely a typo? Please tell me it's a typo...
     
  6. Pollowick

    Pollowick Well-Known Member

    Wet electrolytic capacitors - there are so many cheap ones out there and as everyone wants cheap consumer goods the manufacturers use those to save a few pence on each. They are in so many items from simple PSUs upwards and it is a well known repair. There are some websites that sell capacitor packs for specific devices that are known to fail frequently.
     
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  7. diy_nixy

    diy_nixy Active Member

    Good timing on this thread. Can you point me in the right direction on some articles?

    My 8 year old LCD Samsung TV "blew up" a couple of weeks ago. I say "blew up". It made a kind of "pop-pfffh" noise. I was going to skip it or put on Gumtree for free. But would be nice to have a tinker in-between house diy jobs. Failing than my 2-year old would have fun taking it to bits with my screwdrivers - she loves tools already.
     
  8. Allsorts

    Allsorts Well-Known Member

    Ah! The pop-pffffh!

    Yup, definitely a blown electrolytic capacitor, in your case a 470uF 25V jobbie to be found there. Just there - can you see where I'm pointing?

    Ok, scrub that last bit, but a popped cap is almost certainly what it is.

    Unplug TV, allow to 'settle' for a good half hour to reduce likelihood of stored voltages ready to give you an almighty belt, and then remove the back cover.

    Keep your 2-year old tightly leashed to a table leg.

    Use a torch and good eyes to scan all the capacitors, starting at around where the mains cable connects. I think your culprit will be very obvious - good chance it has blown its top*.

    Also do a Google for that exact make of TV and 'fault' or even 'capacitor' or 'power supply' - see what comes back.

    Are you up for a bit of soldering?

    Which model is it?


    * https://www.google.co.uk/search?q=b...C-wKHZtsDXEQ_AUICigB&biw=1280&bih=579&dpr=1.5
     
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  9. retiredsparks

    retiredsparks Well-Known Member

    "toxic flux and lead vapours"
    I knew there was a logical reason.
    lol
    RS
     
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  10. Allsorts

    Allsorts Well-Known Member

    (Shall I tell RS or will you? Or shall we just snigger quietly...)
     
  11. btiw2

    btiw2 Well-Known Member

    *shudder* surface mounted components.

    A while back I had to replace the micro-switches in my wife's car remote.
    There I was, increasingly long sighted with age[1], my hands shaking with the DTs, trying to solder a couple of surface mount switches in the middle of a board.
    It was a comical. I burnt and melted everything within a 10 mm radius of those bloody contacts.
    It worked though. Nobody was more surprised than I was.

    [1] A side effect of childhood vaccinations.
     
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  12. Allsorts

    Allsorts Well-Known Member

    :D

    Flushed with success, my next take-on is a DAB radio which - stupidly - has its external power supply connected via a USB socket. As can be seen by the plenitude of faulty units on t'Bay, this is a very common issue on these sets - thank you, John Lewis. (I confess I did buy it cheap for this very reason, thinking I could quickly effect a repair, wot with my incredible skills.)

    Well, not only was the USB of near-invisible 'micro' size, but it was also surface mounted. Hmmm, special purchase of a temp-controlled soldering iron complete with set of 'bits' required, one being teeny-tiny pointy end.

    Socket persuaded in to correct place, soldering iron touched gently on first contact - phew, seems to have taken. Next one... that looks okish too, but could perhaps do with a touch more solder. Third, yup, but barely holding - definitely needs a bit more solder...here...we...go...- OH ****! Pool of solder bridging at least three pins.

    Don't panic - clean iron, gently remove solder in stages. Damn, pads still being bridged. Scrape scrape - ok, the pads are now lifting... :oops:

    New purchase - 3.5mm DC power socket and PSU :(
     
  13. facilities

    facilities Guest


    I can’t believe what I’m reading here, you have zero knowledge about electronics and you have touched lucky and fixed summat by sheer chance,

    You now considere yourself an expert and are giving advice to all & sundry.

    It will all end in tears.

    https://www.google.com/url?sa=t&source=web&cd=5&ved=0ahUKEwiSpJizq-_cAhXJCsAKHd-zDnkQt9IBCCYwBA&url=https://m.youtube.com/watch?v=0gGY4FgUViI&usg=AOvVaw2YzaPwYLdrokZdmAQKUL96
     
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  14. btiw2

    btiw2 Well-Known Member

    I thought we’d had enough of experts.
     
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  15. retiredsparks

    retiredsparks Well-Known Member

    lets hope so...
    I was actually hoping it was going to end in electrocution.
    :p
    Rs
     
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  16. longboat

    longboat Well-Known Member

    And that is why we 'all' adore, DA.
     
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  17. Allsorts

    Allsorts Well-Known Member

    Plug it in, Joe, and let's see what happens.
     
  18. gadget man

    gadget man Well-Known Member

    I can honestly say I've never heard anything go 'pop-pfffh' before.:D
     
  19. chippie244

    chippie244 Well-Known Member

    Happens most Fridays with me :)
     
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  20. gadget man

    gadget man Well-Known Member

    Maybe you should lay off the Bass then?,,:D
     

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