Diode question

Discussion in 'General Electronics Chat' started by ricker24, Sep 22, 2012.

  1. ricker24

    Thread Starter Member

    Mar 5, 2011
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    Hello, I am trying to repair my Samsung TV power board. I have one diode that showed when I tested it with my Fluke meter contact through both ways and I have not been able to get it to show that again. Now it just shows contact one way. Is this a sign of it going bad? The diode is marked IN4746A. I can not find any diodes anywhere with this number for sale other than an IN4746 zener diode and this diode does not look like a zener. It is black with a silver stripe on one end. Is there any diodes that anyone knows that would work in place of this one in case it is bad. I also have a couple of capacitors that look to me like are bulged just a bit on the top so I am going to change them also. I was also wondering if anyone could tell me a replacement for them as I don't have any with the correct values. They are 47uf 50v. Should they be replaced only with the same uf rating. I know that I can go up on the volts but not sure on the uf. Thanks and any help appreciated.
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,414
    3,353
    1N4746A is an 18V 1W zener diode. This is a common part so replace it with the same.

    Replace all bulging capacitors with the same capacitance. Do not go with a lower voltage rating. It is ok to go with a higher voltage.

    Before you remove electrolytic capacitors, make a note of the polarity and how they are installed. Make sure you install the new caps correctly.
     
  3. panic mode

    Senior Member

    Oct 10, 2011
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  4. ricker24

    Thread Starter Member

    Mar 5, 2011
    53
    0
    You say these are a common part but I can not seem to find them anywhere. Can you give me a link to where I can purchase them? Thanks.
     
  5. BSomer

    Member

    Dec 28, 2011
    433
    106

    http://www.findchips.com/avail?part=1N4746

    Pick one...
     
    absf and MrChips like this.
  6. ricker24

    Thread Starter Member

    Mar 5, 2011
    53
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    Thanks for the links. I found several that say they are the same number(IN4746A) but even with the same number they do not look like the one I have. Does it matter? Thanks. The one I have is just plain black with a silver stripe at one end.
     
  7. BSomer

    Member

    Dec 28, 2011
    433
    106
    No it will not matter. Generally they are going to be the same thing, though manufacturers may change the body style on occasion.

    Another thing I have noted is that you keep referring to a number that seems to be incorrect. The leading character you use is "I", where it is usually a number "1" when dealing with diodes. A part number leading with "1N" is a simple diode, where as a part number leading with "IN" is generally something else entirely (usually an op-amp). The part you describe as having a black body with a silver stripe is a diode.
     
  8. ricker24

    Thread Starter Member

    Mar 5, 2011
    53
    0
    Thanks to everyone for all of your help. I didnt even notice that it was 1 and not I. I actually believe the diode is fine. I removed it and tested it and it seemed to be fine so I guess I will have to figure out what else is wrong with my TV. Thanks again.
     
  9. BSomer

    Member

    Dec 28, 2011
    433
    106

    What problems are you experiencing with you tv? There are many here on this forum that can help you through the diagnosis of your problems. Just give us a detailed explanation and maybe some pictures. I know one member here in particular, R!f@@, seems to love this kind of stuff. He is good at troubleshooting problems. Even when there are thousands of miles separation.
     
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