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What can cause a capacitor to blow on an IC?

Discussion in 'General Discussion' started by Tesla, 22 May 2006.

  1. Tesla

    Capodecina

    Joined: 19 Jan 2003

    Posts: 17,410

    Location: Bristol, UK

    My knowledge of IC's is limited. I have the tools and knowledge to replace individual components though.

    Mum has a really old Kenwood food mixer, very strongly made and until yesterday had worked fine.

    Apparently it started smoking loads.

    So I took it apart and the motor looks fine, had a look at the simple IC and two capacitors look blown, well they are blown. Literally.

    One is 0.1 x 10-6 F and one is 0.15 x 10-6 F.

    How much would these components cost? How likely is it that other components have been damaged (there are not many of them!)? What is the likely cause of them failing?

    Regards,

    Chris
     
  2. benjo plz.

    Capodecina

    Joined: 15 Jan 2004

    Posts: 14,208

    Location: Hall

    a few pennies tbh. I wouldn't recommend replacing them though, best to buy a new mixer tbh.
     
  3. fatty1

    Gangster

    Joined: 28 Mar 2006

    Posts: 485

    If its old old age will make components fail normaly due to build up of crud but electrical items all have a shelf life
     
  4. Tesla

    Capodecina

    Joined: 19 Jan 2003

    Posts: 17,410

    Location: Bristol, UK

    Why would you recommend against replacing? I think it's about 20years old.
     
  5. VeNT

    Capodecina

    Joined: 9 Jan 2003

    Posts: 20,674

    Location: Cornwall

    being soldered on backwards is always good for blowing up electrolitic caps
    that or runing at too high a voltate etc will always cook any IC
     
  6. Tesla

    Capodecina

    Joined: 19 Jan 2003

    Posts: 17,410

    Location: Bristol, UK

    Mum said the mixer was running on max when it occured.

    I think I will get a pic of the IC to assist in ordering the correct parts.
     
  7. SourChipmunk

    Sgarrista

    Joined: 9 Nov 2003

    Posts: 9,474

    Location: The Motor City

    If I'm not mistaken, the caps are used to provide a little additional power to help the motor start from a dead stop. If they've overheaten, the motor itself is probably getting bound up. At 20 years old, that doesn't surprise me.

    You could replace them for a couple quid, but you'll have the problem again very soon. Like Phnom_Penh said, best just to get get a new mixer.
     
  8. m3csl2004

    Hitman

    Joined: 17 Jun 2005

    Posts: 621

    Location: Sheffield

    chances are the chip blew after being at full load, shorting the capactiors making them blow

    btw - blowing capacitors is amzing fun, i recomend every does it
     
  9. Tesla

    Capodecina

    Joined: 19 Jan 2003

    Posts: 17,410

    Location: Bristol, UK

    How about charging them and playing catch?

    Would it be possible to refurn the motor too? Surely it is!
     
  10. m3csl2004

    Hitman

    Joined: 17 Jun 2005

    Posts: 621

    Location: Sheffield

    lol - charging them and playing catch can be fun - but not as satisfting at blowing stuff up :cool:

    tbh if its 20 years old replacment chips will be hard to find
     
  11. William

    Capodecina

    Joined: 26 Jul 2003

    Posts: 10,948

    Location: Derby

    How does one blow them up?
     
  12. VeNT

    Capodecina

    Joined: 9 Jan 2003

    Posts: 20,674

    Location: Cornwall

    solder them on backwards
     
  13. William

    Capodecina

    Joined: 26 Jul 2003

    Posts: 10,948

    Location: Derby

    Sounds fun, you are responsible for my eyes if anything goes wrong by the way. ;)
     
  14. m3csl2004

    Hitman

    Joined: 17 Jun 2005

    Posts: 621

    Location: Sheffield

    dude....

    turn the power supply on after your a good metre away, youll be covered in capacitor inards (paper/foil or liquid and metal dending on the cap)


    edit: after my electronics exam tomorrow i may celerbrate in a rather relavant way and video it ;) - depends if i can get a decent power supply though, screw using mains, last time i did that......
     
  15. Tesla

    Capodecina

    Joined: 19 Jan 2003

    Posts: 17,410

    Location: Bristol, UK

    Just had the motor apart and it looks fine. It's doesn't even looked used and moves very freely.

    The cake mixer still actually works.

    I have been chatting to Adam on MSN and have sorted out most of what I need so going to get the parts (cheap as chips) and replace them. Then see how it goes.

    However, 2 of the capacitors we are unsure on.

    We think they are 25 pico Farad (x10^-12 ???)

    Anyway, if you could take a look at this pic and let me know what you think they are. Cheers!

    [​IMG]
     
    Last edited: 23 May 2006
  16. sinister_stu

    Gangster

    Joined: 15 Nov 2002

    Posts: 447

    The 250 is the clue... there's no standard for capacitor labelling so not sure what value it is. Usually they are in uF of pF though. The part behind the capacitors is a crystal oscillator though, resonant frequency of 3.8MHz.
     
    Last edited: 23 May 2006
  17. VeNT

    Capodecina

    Joined: 9 Jan 2003

    Posts: 20,674

    Location: Cornwall

    need better pics (different angles etc) but I'd say that it was the ossilater behind that is the issue
     
  18. Tesla

    Capodecina

    Joined: 19 Jan 2003

    Posts: 17,410

    Location: Bristol, UK

    On the top it "read" 0.15microF @ X

    I thought it was an X rated capacitor.
     
  19. VeNT

    Capodecina

    Joined: 9 Jan 2003

    Posts: 20,674

    Location: Cornwall

    what
    with boobies etc?
    niiiice
    porn microwave
     
  20. sinister_stu

    Gangster

    Joined: 15 Nov 2002

    Posts: 447

    0.15uF @ X means that at the resonant frequency, the oscillator will be a capacitive load. Not especially important to you, but necessary to know when you're designing a circuit incorporating it.

    Best bet for replacing the crystal (if required) is to take that component to a high street electronics store and see if they can match it.