what is this component on crt tv neck board..

Discussion in 'General Electronics Chat' started by tpny, Jun 8, 2014.

  1. tpny

    Thread Starter Member

    May 6, 2012
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    1. please see attached pic, it's the silver one that looks like an oscillator says 104 something.. what is it? thanks!

    2. Where do I locate the 3.58 Mhz oscillator (I think this is for the chroma circuit..) in a crt tv? is it on the main board or the neck board?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Mica capacitor 0.1μf
    The 3.58 xtal will be on the chroma board, if you can locate it.
    Usually stands out.
    Max.
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,126
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    +1

    104 = 100nf
    J = 5%
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The yellow part with 104J on it is an 100 nF 5% capacitor.

    Bertus
     
  5. #12

    Expert

    Nov 30, 2010
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    "10" plus 4 zeroes (in picofarads) means .1 uf
     
  6. tpny

    Thread Starter Member

    May 6, 2012
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    uh, where is the chroma board? is that the mainboard? not the neck board right? Thanks!
     
  7. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Main board. Usually the parts on the CRT neck are related to convergence - getting the electron beams from the red, green, and blue guns to align correctly.

    Even with surface mount components on the bottom side, usually the crystal is a top side component. They almost never fail, so why are you looking for it?

    ak
     
  8. tpny

    Thread Starter Member

    May 6, 2012
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    My crt tv powers on in color but after several minutes (warm up?) it turn b/w. I poked around on google and some article mentioned xtal might need replacement.. Any other possiblilities I should look into? Thanks!


     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If you can locate the Chroma section, you can use a aerosol can of 'Artic Air' to freeze suspected components and see if freezing a particular component brings it back.
    Xtals do not normally fail like this, usually a semiconductor associated with it, or in the chroma section.
    Normally nothing attached directly to the CRT itself will cause this problem.
    Max.
     
    Last edited: Jun 9, 2014
  10. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Agree. "after several minutes" is a classic thermal problem symptom. Could be a bad or missed solder joint, where something making friction contact moves a fraction of a mm with heat.

    ak
     
  11. tpny

    Thread Starter Member

    May 6, 2012
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    ok, i can believe that. what's the physics behind freezing making it work again?

    took some more photos. i swapped out the 3.58Mhz xtal - no difference, I looked on the underside of the pcb, i see some orange grud around solder joints, i think some of that short out the pads, what is that orange thing anyway? so i cleaned it out with hydrogen peroxide because i have no alcohol and let it dry up (photos show after cleaned out). Tv seems to be in color now when i turn on, but need to leave it on for a while to really know if that did the trick..

    also, what is that toshiba chip? is that the chroma chip? online datasheet only reads in japanese..


     
  12. tpny

    Thread Starter Member

    May 6, 2012
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    that's great observation! thanks

     
  13. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Probably a dated version of Toshiba TA8759B which is out there in app sheet.
    I think the Arctic-air trick is your best bet, components often change after current/heating and taking them back to ambient or below, brings them back for a while.
    It's a very old servicing trick.
    Max.
     
    Last edited: Jun 9, 2014
  14. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Resolder that jungle chip. I can see multiple pins with full circle fractures from here! :eek:

    Make sure to add fresh solder to every joint, and keep wiping that old dirty solder off the soldering iron tip.
    :)
     
    Metalmann likes this.
  15. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    The orange crud looks loke old flux. Usually not a problem, and when it is it isn't thermally dependent.

    Also, there probably isn't a single "color chip". Several, or maybe all, bvideo signal processing can easily fit in a 40 pin DIP of this vintage. The 8759 mentioned above takes the output of the IF stages and does all video, chroma, and sync processing for three different broadcast video standards.

    ak
     
  16. ian field

    Distinguished Member

    Oct 27, 2012
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    Not always - the subcarrier crystal is sometimes hidden in a tinplate screening can, usually with a large chip with lots of close spaced pins.
     
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