K3706 (2SK3706) N Channel Mosfet from Sharp TV

Discussion in 'Electronics Resources' started by trader007, Jul 20, 2013.

  1. trader007

    Thread Starter Active Member

    Feb 27, 2010
    It appears to be this here, found on this datasheet-


    Silicon N channel mosfet it seems.

    Problem is, the only one I can find online is from maylasia. Now, I will order it if I have to, but I was hoping someone could help me finding a substitue off digikey or something.

    This is out of the right side inverter board from a Sharp LC52D64U Tv.

    What trips me up is I can't even find any "silicon N channel mosfets" on digikey... Does the replacement have to be silicon, or is that even any different the the metal oxide ones they list?

    Much thanks for the help! I have been struggling with this tv for months now, and I think I'm down to this last fet. It is shorted 0 ohms across all legs.
  2. panic mode

    Senior Member

    Oct 10, 2011
    trader007 likes this.
  3. trader007

    Thread Starter Active Member

    Feb 27, 2010
    you da man. thats what i was thinking, but i am glad you chimed in.

    I will order a couple, and hopefully have a working tv soon! My problems were first with the power supply itself, the secondary transformer was shorted out. Couldn't find a replacement, so I ordered a whole new board (only $40!).

    That fixed part of my problem obviously, as I now have a specific blink code. Before I even read up on what the code meant, I traced another short back to this mosfet on the inverter board. Surprised I didn't catch it before, but again it looks like I needed both boards repaired anyway. I am guessing the inverter's fet slowly died, drawing down some parts on the power supply, which eventually gave up.

    I'll post back in a few days with results! thanks again.
  4. trader007

    Thread Starter Active Member

    Feb 27, 2010
    Well the fet allowed the tv to hold for a few seconds, then the fet blew again. lights never came on. I gave up, knowing a replacement board is $40.

    Installed the new board, and the TV works perfectly! :D
  5. #12


    Nov 30, 2010
    That's why I quit fixing them. They drive me crazy! All that interdependent stuff conspiring to do multiple murder/suicide pacts at the same time! You would have to work them full time to get good at tracing the cascade of dead parts, and them the manufacturer would change the design.

    Where's that GIF of shooting myself in the head...
  6. trader007

    Thread Starter Active Member

    Feb 27, 2010
    yea! and it makes it worse when the service manuals don't provide schematics.

    When I was in a TV repair shop, the only real component testing was done when you had previous knowledge of common failures for that particular model. Otherwise, it's just easier to try and guess what board is at fault, and swap it.

    This TV though, it was both the power supply board and the right side inverter. I actually thought it was the mainboard at first, because with just that and the power supply hooked up, it would click in and out. But to even test the voltages out of the power supply doesn't tell you much since the motherboard has to properly signal the power supply before it will fire up.

    Once I got a new mainboard and verified the symptoms were unchanged, it was a little easier. New power supply would at least let the TV flash error codes, and that is what lead me to the inverter.

    On top of all that, the manufacturers also have diagnostic tools that they won't allow anyone else to have, even their authorized service partners. You see tons of test points on these boards too, but they won't tell you what the values should be in any given state... It really is just a giant pain in the end. They expect you to reverse-engineer every board in the TV, and when the TV only costs $400 there simply isnt enough time to do so economically.

    Oh well. I got this 52" aquos for $35, and I have a whole $200 into it total. Turned out to be a pretty nice deal despite the time I have in it! Dad is going to hang it on his wall... he still doesn't know what HD is, but he will! :D
    #12 likes this.