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Creative A520 Speaker, burnt power supply in lightning

Discussion in 'Repairing Electronics' started by Solder Guy, Sep 15, 2015.

  1. Solder Guy

    Solder Guy New Member

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    The power supply of my Creative A520 speaker system got nuked in lightning. I tried an external adapter 12V/1Amp and it works with occasional volume loss during heavy bass. I guess the adapter is unable to supply enough current.
    I am trying to repair the power supply but cannot figure out the values of the burnt parts.

    I can see two resistors and a zener diode as burnt:

    Please help me figure it out. circuit.jpg
     
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  2. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Oh dear, not a pretty sight :(. I think your best hope is to find someone with the same model supply and get the values from that. There's a good chance the IC is fried too: the board near its pins looks to have delaminated? Can't spot any datasheet for that IC in a quick search.
     
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  3. Solder Guy

    Solder Guy New Member

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    Its a PWM controller and its datasheet claims 100% avalanche testing. I guess it means it can withstand high voltage but not sure.
    The power supply is quite common and based on Fairchild FQPF8N60C MOSFET.
    I also figured out the diode to be a 1N4148 high speed one. Now just the resistors need trial and error.
     
  4. dave

    Dave New Member

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  5. tunedwolf

    tunedwolf Well-Known Member

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    This might help: http://www.datasheetbank.com/CR6853T-Datasheet-Chip-Rail.html
     
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  6. vtech

    vtech Member

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    As it was mentioned, your best bet is to find someone who has the same unit.

    In the mean time, there is a hi-res picture of exact power supply happened to be posted on a Turkish forum! Some of the parts are pulled out but you might open it up in a separate browser or an editor for blow up, I think you can see the bands---by the way it is going to be more than the resistors faulty. I can see a(red red blk) 22ohms and the other is 4 7 something.

    Hope that helps.


    [​IMG]
     
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  7. Solder Guy

    Solder Guy New Member

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    Thanks a lot guys. I would have never thought about the Turkish forum.
    I think the diode was used to signal PWM and after its blown the whole unit shutdown.

    My current guess is 4 burnt parts (right to left):
    Diode: 1N1418
    Resistor: 22R
    Resistor: 4R7

    Big Blue Resistor below-left the heat sink: 0.33R

    I will get the blown up parts from local radio shop along with the Chip Rail PWM IC (CR6853T) and FairChild MOSFET (FQPF 8N60C) provided they are cheap :) ;)
     
  8. xTatshx

    xTatshx New Member

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    can is ask about the turkish forum??
    need reply thanks..
    i just need to know about the voltage and power of that thing....
    coz i want to convert it to linear power supply(with huge transformer thing?) without lacking of power or burning my Audio ICs
    thankz...
     
  9. vtech

    vtech Member

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    Not sure but I think the picture was originally posted here;
    http://forum.donanimhaber.com/
    Whether you can get the information is another story. Plus modifying a SMPS to a linear does not really make sense unless I am missing something here? Why not build your own linear supply? If you don't know how, there are tons of info/schematics on the net.
     
  10. bountyhunter

    bountyhunter Well-Known Member

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    Just by looking:

    the power supply looks pretty standard. I believe it's an offline flyback converter. The transformer (far right) provides isolation. There is also an opto coupler to provide isolated feedback. In most cases there is some kind of proprietary IC in there driving the switch FET (on the heatsink). Bottom line, if it got hit by lightning you would probably need to replace all the electronics even the capacitors. The other option is to unsolder all the P/S components from the board and just hard wire in an external 12V source. You can usually find lots of them on ebay very cheap.

    12V/5A adapter for $10.

    http://www.ebay.com/itm/12-Volt-5-A...499669?hash=item1c5fbff415:g:7r0AAOSwqrtWmBsw
     
    Last edited: Apr 18, 2016
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  11. Solder Guy

    Solder Guy New Member

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    The optocoupler has some lines on the edges. Does it look burnt?
    I checked with a new one and the diode readings are same.
    My circuit after damage 2.jpg
     
  12. xTatshx

    xTatshx New Member

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    I' ve used 12Vdc 5Amp SMPS(Commonly found on CCTV systems) to supply the Unit and It sounds Fine without cracking the sound, even i Tune to its maximum Volume no cut offs.
     
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  13. Solder Guy

    Solder Guy New Member

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    Thanks xTatshx.

    That's my last resort. I think the power requirement is 4.2 Amps. I have adapters till 3.33 and it didn't work. Basically I wanted to learn about SMPS circuits after it blew up and it has helped a lot in that regard.

    I also tried to power it using 12V rail from my desktop power supply. It was able to supply the current but lot of static noise was there. I think I can put some combination of inductor and capacitor to filter it and then the speaker will work even better with it. It will switch off when the computer goes to sleep.
     
  14. Umair Hussain

    Umair Hussain New Member

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    Can anyone please confirm these 4 encircled components? The FET I believe has been mentioned already. Can someone please tell me the value of the resistor (R4), the diode (D5) and the light blue capacitor.

    [​IMG]
     

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  15. alec_t

    alec_t Well-Known Member Most Helpful Member

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    The link is broken. Use the 'Upload a file' button to upload the image to this site.
     
  16. Umair Hussain

    Umair Hussain New Member

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    Edited, visible now?
     
  17. Solder Guy

    Solder Guy New Member

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    I got a new 12v 5Amps SMPS but its still struggling with bass. Also the copper in some speaker wires had black dust (carbon?). I think the lightning damaged components on the amplifier too :nailbiting::nailbiting:

    umar:
    FET = FQPF 8N60C
    R4 = 560K
    D5 = RL207
    Blue capacitor = 101 1KV = 100pF 1KV

    I have the big blue 1W resistor (R3) damaged beyond recognition, can you please tell me its value.

    Thanks


     
  18. Alexandre Neves Lopes

    Alexandre Neves Lopes New Member

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    Hello ladies and gentlemen.
    I have the same home theater , but my problem is that the motherboard sound is missing a component. This component has 9 contacts on the board. I need to know if someone could post the picture here that card so I can identify it and then search to try to find it , because without knowing their identification can not. It could also be the card scheme.
    Thank you very much.
    Hug.
     
  19. Solder Guy

    Solder Guy New Member

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    Kindly post a picture giving the location of the missing IC. Most ICs on the amplifier board have large heat sinks on them so its not easy to point. Also the PCB will have some marking like U14 for the missing IC.
     
    Last edited: Sep 20, 2016
  20. Alexandre Neves Lopes

    Alexandre Neves Lopes New Member

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    Hello . Here are the photos of the controller board . I took the liberty to indicate the missing component of the position. This is an IC with 9 legs audio controller. The exact function of it I can not tell.
     

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  21. Alexandre Neves Lopes

    Alexandre Neves Lopes New Member

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    Hello, Solder Guy.
    Any news about the missing component of the identification of the main board?
    I appreciate if you can cooperate.
    Hugs.
     
    Last edited by a moderator: Sep 24, 2016

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