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Technika lcd tv

Discussion in 'Troubleshooting and Repair' started by spike47, Aug 14, 2009.

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  1. spike47

    spike47

    11
    0
    Aug 11, 2009
    Hi

    I have a problem with a 19" Technika lcd tv , when it is swiched on all that happens is the red standby light is going on and of , and a small ceramic capacitor is clicking away , I have a sort of schematic and photo of the area of the pcb in question , I have removed one of the 2 shottky rectifiers for testing and It showed to be faulty , I have ordered a new one , but when I switch on the board the small cap is still clicking away , could this be a fault with the cap , ( 103 1kv ) I am not sure how to test it and if it has to be removed to test .

    any help on this will be highly appreciated.
    ps: I have a drawing I have done , but I cant reduce it to fit the sites size's , I ould PM anyone that is interested .

    spike
     

    Attached Files:

  2. charles

    charles

    3
    0
    Aug 25, 2009
    technica 19 in tv

    Had the same fault and replaced shottky d102 which was s/c. this cured fault.
    If you switched on tv without diode in place you have probably blown the capacitor.
     
  3. chainey44

    chainey44

    3
    0
    Oct 23, 2009
    Could you point me in the direction of the replacement shottky please - ie. vendor and product code? I have the exact same problem, with clicking from the PCB and flickering power LED. Is it likely I'll need to replace the capacitor you refer to as well?

    Many thanks in anticipation...
     
  4. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    It's very unlikely that the 10nF 1kV cap is faulty, or even making the sound you hear, it's usually the transformer that has acoustic properties. You could of course desolder the cap and test it on a DMM so equipped,
    If after replacing the schottky rectifier it still clicks then I'd expect there to be more shorts in the secondary circuit. The clicking is a short-circuit protection scheme and shows that the primary circuit is operating properly.
    It's hard to test if the transformer has a short.
    Feel free to PM me.
     
  5. charles

    charles

    3
    0
    Aug 25, 2009
    diode is vf20100sg available from www.dalbani.co.uk
     
  6. maccyd10

    maccyd10

    2
    0
    Nov 9, 2009
    Huh, Ironic I should just stumble across this thread today after spending a good couple of hours yesterday fault finding my LCD191D - 107. However, I too arrived at the conclusion of d102 being the likely culprit. Device confirmed as shorted after removal with my trusty ol' meter.

    I ordered myself a replacement off ebay, (slightly cheeper than dalbani by the time you account for P&P)

    Ebay item 200395989756 still 3 available for the next 7 days.

    Wish my luck I'll let you know the out come if those slackers at the royal mail get around to delivering my diode :)
     
  7. maccyd10

    maccyd10

    2
    0
    Nov 9, 2009
    Yup, D102..... Problem Solved.

    Looks like it might be a common problem with this set.
     
  8. chainey44

    chainey44

    3
    0
    Oct 23, 2009
    Well thanks very much Charles and Resqueline, your help is much appreciated and has enabled me to repair the Technika which was headed for the scrapheap. The repair cost less than £10 and was relatively straightforward, despite my complete inexperience with soldering etc.

    One question though - the diode I replaced seemed fragile, which leads me to think it had got very hot either prior to, or when it failed. Might temperature play a part in the failiure of this component and could it be worthwhile incesing heat dissipation in some way, perhaps a very small laptop IC fan?

    Thanks again, Max
     
  9. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    Glad to have been of assistance.
    A local fan just for the diode seems impractical (although it could work), better then to find a bigger or more efficient diode, or to heatsink the small one.
    Some flatscreens can benefit from the airflow of (a) chassis fan(s) though.
     
  10. Jellybean

    Jellybean

    4
    0
    Apr 23, 2010
    Same Again

    Apologies for reviving this thread but I have exactly the same 'flashing standby light of death' as Spike 47 and Chainey 44 on my 2 year old Technika LCD19DVDID-207.

    As a complete novice I am wondering whether I have the ability to repair this myself, not really wanting to consign this 2 year old TV to the scrappy.

    I have attached a picture of my circuit board (next page) and was wondering if anyone could direct me to which Shottkey it is that I need to replace, A, B or C? (They all look the same!)

    I am a little confused as Chainey stated that it was the D102 that was not working, this is letter A on my picture (next post). I note that this appears to have 4 connectors at the base yet the replacement part shown on the Dalbani website only appears to have 3. ???

    If anyone can give a complete novice any top tips regarding this job then I'd be very grateful. If I am right in over my head here then please say, I'm thick skinned :) I have never atempted anything like this before but am willing to give it a try.

    Many thanks in advance. Andy
     
    Last edited: Apr 23, 2010
  11. Jellybean

    Jellybean

    4
    0
    Apr 23, 2010
    Here's the pic of my board.
     

    Attached Files:

  12. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,418
    2,788
    Jan 21, 2010
    My guess is that it's A, but notice that your board is a different revision (it has a heatsink whereas the earlier one had a single transistor(?) and markings for where the heatsink used to be. (I would say yours is the earlier revision).

    Check the part number on the device marked A and get back to us.

    edit: It's a shame that both photos show different details. I would not be surprised if this was the inverter for the backlight.
     
    Last edited: Apr 24, 2010
  13. Jellybean

    Jellybean

    4
    0
    Apr 23, 2010
    Many thanks for your reply Steve. Unfortunately the part number isn't very clear (it appears smudged). I've taken a pic, not sure if this is helpful. The marking on the board just below the Shottkey is 'D102'.
     

    Attached Files:

  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,418
    2,788
    Jan 21, 2010
    That device has 6 legs!

    I'd be somewhat surprised if it's the same part as in the other power supply.

    I can make out a few letters of the name, but not enough to be really helpful :-(
     
  15. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    Device A is not D102 & is not a Schottky diode. Please look again. And while you're at it you can wipe the heatsink paste smudge off the part number on device A..
    I recognize device A as being an integrated off-line switchmode controller/driver made by Fairchild. I can get back to you with an official part number for those if need be.
    But if the PSU is clicking then this is not the faulty device.
     
  16. Jellybean

    Jellybean

    4
    0
    Apr 23, 2010
    Yes the PSU is clicking Resqueline, along with a flashing standby light. Any ideas what the problem might be and whether I might be able to repair it? Or is this set destined for the skip? :(
     
  17. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    Well, are you able to locate & measure D102 (& all other diodes too) then? Also check the small alu-lytic capacitor close to device A.
     
  18. charles

    charles

    3
    0
    Aug 25, 2009
    board looks slightly different but d102 on my board is position C
     
  19. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,418
    2,788
    Jan 21, 2010
    Please see here for a possibly similar fault.
     
  20. Jonboy

    Jonboy

    6
    0
    Jul 26, 2010
    LCD191D-107/207

    LCD191D

    Hi one & all.... New to this forum, so be gentle with me.

    My problem with this 2 year old Technika is that on powering up, a dull picture appears for 2 seconds, then disappears. Sound remains on - a quick turn off and on again, either from standby with remote, or directly from mains switch, produces a dull pic for 2 seconds. Presumably a PSU fault?
     
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