Help identifing a part on motherboard

Discussion in 'General Electronics Chat' started by lilunwl, Mar 29, 2009.

  1. lilunwl

    Thread Starter Member

    Mar 29, 2009
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    Hello all!!! I am new yes but im hoping that I can get some help here. I have a motherboard that im trying to figure out what this part is that is burnt out. It is in a dell sx270. I know most of you may think "its not worth fixing" But this is something im playing with. Its not my primary computer its just one I got from my sister cause it "burnt up". I would like to know if this part is replaceable and where to get it and what it is ofcoarse. It looks to me like a small microcontroller but I cannot find any info on it. I am kinda familar with microcontrollers because I mod xbox 360 controllers but this is totally different. Im going to try and upload a pic. So please if anyone can steer me in the right direction I will appreciate it greatly. And like I said I know alot of people think "its not worth replaceing the part" but thats not what im asking. Im asking what is it, where to get it, and if it is possible to replace it. Yes I have soldering skills. Thanks in advance!!! Oh I almost forgot. This is the letters and numbers on the part VHC 08 D518
     
  2. leftyretro

    Active Member

    Nov 25, 2008
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    It's not worth trying to find the correct replacement. ;)

    Lefty
     
  3. lilunwl

    Thread Starter Member

    Mar 29, 2009
    17
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    LoL I know. Its something I want to do for fun. Thats really not the answer im looking for but thanks anyways ;-)
     
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    More than likely, you need new capacitors instead of that IC http://www.badcaps.net Check that link and see if your problem matches.
     
  5. loosewire

    AAC Fanatic!

    Apr 25, 2008
    1,584
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    We have what you call big trash days.People put all kinds of stuff
    out to be picked up twice a month,I know a school that going
    throw out maybe 20 computers.Post the part number, look throw outs
    in your area. 20 thousand working computers have been tossed for
    replacement.
     
  6. lilunwl

    Thread Starter Member

    Mar 29, 2009
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    Thatoneguy ..Its not the capacitors. The part I have the arrow to is bad. Its legs are burnt to a crisp. I know for a fact that it is bad. I know about the cap. issue with these computers. Thanks Though I greatly appreciate your info.

    loosewire..Trust me I always look for old electronics on trash day :-D I would rather have fun with these things then let them go to our landfills. :-D Thanks for the advise!!!
     
  7. wr8y

    Active Member

    Sep 16, 2008
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    If you can find the right part, how are you planning on changing it?

    What Soldering (and de-soldering) equipment do you have?
     
  8. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    If it's any consolation, it is the SMPS controller for the 1-2V supply for the CPU.
     
  9. lilunwl

    Thread Starter Member

    Mar 29, 2009
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    wr8y... Yes I can desolder and solder. Its no different then an xbox 360 controller and that is what I do most. Thanks for the concern though!!

    thatoneguy....Thank you for the name of the part. Any idea if it is "possible" to replace or is it something that will only work on the board that it was made for? I know its possible to desolder and solder. Just didnt know if function wise if it is possible.Any idea where I could get this part? Thank you for your help!!
     
  10. wr8y

    Active Member

    Sep 16, 2008
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    I was not concerned, I was honestly asking - HOW are you going to get the old part off the board?

    And how are you going to solder pins so close together?

    I have tried, and failed at such small SMT devices. What's your secret? Your technique? Or do you have $8,000 of SMT rework equipment? :confused: I have always believed, "Where there is a will, there is a way", but perhaps half the time, I end up lifting traces or pads from the board. Not ALL the time, but too often, IMO. Perhaps the boards I am working on are too cheaply built!

    I use a PACE desoldering set with an SMT tip for desoldering and a temperature controlled iron with a TINY tip to tin the pads and solder in the new part. This works for many of the SMT devices, but if they are too small, the pads will lift too easily without real SMT rework equipment.

    How are you doing this?
     
  11. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    iwr8y, you must be using way too high tip temprature, otherwise I can´t imagine how do you manage to lift the pads. In school I used some Rework jelly for soldering, it made the job much easier, also the desoldering braided copper can help a lot.
     
  12. beenthere

    Retired Moderator

    Apr 20, 2004
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    It may be lead free solder. Flood the pads with the real stuff (leaded) and see if the stuff doesn't come off more easily.
     
  13. wr8y

    Active Member

    Sep 16, 2008
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    It seemed to me that I was trying too hard to NOT lift the pads - setting the temp to 750F worked better than 675F or so. Seemed like the lower setting meant that I had to sit on the part's leads too long, speading heat all around!'

    But what are you guys using for REMOVAL? With smt parts having such short leads, I can't (as I did years ago with larger parts) cut the legs off and remove them one at a time.

    It's in the REMOVAL that I am having problems. How are you guys heating all legs at once so effectively??????

    I should add that, when I talk to other shops, they say, "Oh, we dont' bother with those tiny parts, we send that stuff to the depot". Again, WHAT are you guys using to lift the part from the board?
     
  14. wr8y

    Active Member

    Sep 16, 2008
    232
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    What the hell other solder is there? :D I upset the boss when I came here 8 years ago - I ordered smoke filters for the benches, told him I hadn't breathed lead smoke in 20 years and I was not going to start now!

    Really upset him. But he got over it.
     
  15. lilunwl

    Thread Starter Member

    Mar 29, 2009
    17
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    I apologize for misunderstanding!! Ok as far as getting the old part off and new part on. I will tell you I have never done this type of part. But I am confident I can do it just because I have soldered surface mount leds in controllers. No its not the "same" but is similar. I think my tip is a 7/32 tip. Very small. Strong Magnifying glass on my stand. I will try taking it off by heating the solder up on the pins and lift with a bent needle or tweezers starting in one corner and working my way around.. Then once im done taking it off if in fact I can replace it I will basically just put a little bit off silicone on the underside of the chip and align it with tweezers and then hold down with tweezers and touch each pin with the soldering tip loaded with solder. It will run where it needs to run. No I do not have 8,000.00 in rework equipment. Only 7000.00 Ha ha No seriously I dont have alot of stuff. I really dont. Lifting traces I have done my fair share. When taking off the 0603 surface mounted leds I have takin off traces. Then its scrape and fix. YUCK!!! LoL When taking off the parts "TRY" to leave a lil solder left it makes it easier when installing back on.

    I will tell you what. I will "TRY" once again theres that word try. LoL I will try and make a video if I find the part I need. If not I still may try and make one just for people to see and maybe help them. I know I probably didnt help much with what I said Im not good with words and typing.
     
  16. lilunwl

    Thread Starter Member

    Mar 29, 2009
    17
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    Yes desoldering braid works wanders also!!! Forgot to even mention that. I dont use that much on what I do though. But I have used it and yes it works well.
     
  17. wr8y

    Active Member

    Sep 16, 2008
    232
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    How does "desoldering braid" help you remove a surface mount component?
     
  18. Wendy

    Moderator

    Mar 24, 2008
    20,766
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    I've done it, suck most of the solder and it does go easier. I've also done surface mount, both hobbiest and professional. Removal usually consists of sucking up as much solder as you can, then cutting the leads off with fine tipped wire cutters.

    I prefer the hot nitrogen solder removers though, they melt all the solder at once (preventing oxidization in the process), and you just lift her off. They can also cause the board to delaminate, which is the end if it happens.

    Never done it, but I've heard indium solder will alloy with regular solder like a dream, dropping the melting temperator in half. The solder will practically jump off the board if you add a little indium solder while melting it.

    Nowdays the norm is silver solder, 96% tin, 4% silver, mandated by almost every country in the world (including the USA). It is a PITA to work with, and while mechanically stronger has a higher melting point and tends to grow dentrites, causing invisable shorts. Military contractors have already gotten wavers because the stuff simply isn't as reliable. I bought about 5 pounds of lead/tin last HAM fest, and recommend anyone serious about it to do the same. You would think lead was arsinic the way some people talk.
     
  19. wr8y

    Active Member

    Sep 16, 2008
    232
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    Ok, anyone got any secrets about how to remove one of these four IC's (the BIG four on there)?
     
  20. lilunwl

    Thread Starter Member

    Mar 29, 2009
    17
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    By laying the braid across the muliple solder points and heating it with your Iron. It obsorbs most of the solder into the braid. Therefore there is little to none solder left to take off. Not saying it will take the part completely off but it does take alot of the solder off. Search youtube perhaps there will be a video of it being done.
     
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