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can someone help identify the parts to replace?

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    #1

    can someone help identify the parts to replace?

    I have a case mod ccfl inverter that runs very hot and today it suddenly fails. I opened it up and see 2 heavily burnt spots under the transistors.

    I saw D1804 SX 02 markings on both of these pieces but I don't know what compatible parts may be, searching those numbers on google doesn't yield definite results.

    see attached for pictures.

    Is it acceptable to solder a working part back and expect it to work? or I have more work to do before replacing that?

    in the center pin on the transistor both has a brittle texture on the solder joint. so which way the damage goes? bad solder joint caused overheating and killed the chip? or the bad chip overheated and broke the solder joint?
    Attached Files
    Last edited by meanderer; 11-28-2010, 06:37 PM.
    Tags: None
    #2
    Re: can someone help identify the parts to replace?

    The second pic is enough out of focus that I can't quite tell. BTW, is this for effect lighting in your case? I don't recognize the inverter board offhand.

    You might want to check the windings on the transformer with your DMM to see if shorted, but assuming the xformer is ok, you migh get away with replacement of the components. I just cant tell what they are from this pic. Sorry. Maybe another view with better lighting?

    Comment

      #3
      Re: can someone help identify the parts to replace?

      The most likely candidates for failure are the transformer and transistors. The transistors generate the AC sine wave required by the transformer for voltage amplification. They do run HOT! The transistors are possibly 2SD1804 and should be checked for shorts. If one is bad, replace both. Also check the transformer for shorts as romansroad suggested.

      Comment

        #4
        Re: can someone help identify the parts to replace?

        Probably 2SD1804. That's a Royer oscillator circuit. Resolder the transformer pins at the same time you replace both of them.

        PlainBill
        For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

        Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

        Comment

          #5
          Re: can someone help identify the parts to replace?

          I have an identical inverter that doesn't run as hot.

          Yes, this is for case mod lights. It is probably very generic design.

          the bottom pin and the top pin on the right side on the transformer is short. Is that normal or that's the cause of defect?

          I would order something from digikey, which one would work?
          Last edited by meanderer; 11-28-2010, 07:07 PM.

          Comment

            #6
            Re: can someone help identify the parts to replace?

            Originally posted by PlainBill View Post
            Probably 2SD1804. That's a Royer oscillator circuit. Resolder the transformer pins at the same time you replace both of them.

            PlainBill
            Nice! He makes the call from multiple zip codes away and with a slightly fuzzy pic

            As to the windings resistance, are you measuring them out of circuit? I've been fooled by this before. Keep in mind that we're talking low resistances here....say 0.3 ohms anyway so be sure your DMM is able to do this. Once you've figured out which component it is, I love to way oversize my heatsinks on power semiconductors. You can scavange these from old PCB's and screw them on with some thermal grease. Watch out to not have the heatsink touch any nearby metal, as one never knows what potential the other voltages are at.

            There's a place called Moniserv that I've used for xformers, as Digikey's inventory is sparse. I was happy with their service. I recall a guy named Hue, who really knocked himself out looking for a xfomer for my Samsung 215TW.

            Comment

              #7
              Re: can someone help identify the parts to replace?

              Oh yeah, Moniserv lists their transformers by number and primary/secondary resistance....I have subbed in a few that were near the correct resistance and the oscillator circuit didn't notice! Since you have another identical working one, this should be easy to measure the good xformer.

              Comment

                #8
                Re: can someone help identify the parts to replace?

                Originally posted by meanderer View Post
                I have an identical inverter that doesn't run as hot.

                Yes, this is for case mod lights. It is probably very generic design.

                the bottom pin and the top pin on the right side on the transformer is short. Is that normal or that's the cause of defect?

                I would order something from digikey, which one would work?


                Since you have a good identical inverter, try comparing the resistance readings of the good one to the bad one. If it is the transformer, you might be cheaper to purchase another inverter versus the time and money trying to match the transformer.

                Comment

                  #9
                  Re: can someone help identify the parts to replace?

                  I would much rather not do the comparison as the casing is fused and require dremel-style destruction to take it out XD.

                  if I can just replace the 2 pieces and call it a day, I would do that. Otherwise I rather buy another one LOL.

                  Thanks everyone for trying tho.

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