HP laptop Adapter Buzzzzzing

Discussion in 'General Electronics Chat' started by bhvm, Mar 26, 2010.

  1. bhvm

    Thread Starter Active Member

    Jul 16, 2009
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    Hola amigos!

    I have this beast laptop listed here-

    http://www.gadgetsguru.in/hp-pavillion-dv8216tx-notebook-pc-price-specification-buy-india-1351.aspx



    The Adapter is rated for 19v at 4.7A...Which brings it to 90W.
    I've noticed a faint, high pitched whine/buzz from the adapter.
    Since this is from day 1....and has worked wonderfully for 4 years...I see that its not some fault...But by design. However that buzz is enough to irritate my sensitive ears, esp at quiet nights.
    Can any of you explain in detail whats causing this noise? and how could i be eliminated? DELL adapter does not make any such noise.

    Noise is at peak with NO load....and comes down as load applied. Sometime i can spot a Rhythm too (some component might be pulling power in the rhythm)
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Hola.
    Did you consult with HP?
    Problem is in the design if it is brand new, but also it could be a faulty capacitor causing the SMPS to run at audible HF.
    Or it could be a faulty snubber HV capacitor.
    All in all it is HV caps that tend to develop this kind of noise
     
  3. bhvm

    Thread Starter Active Member

    Jul 16, 2009
    53
    2
    Thanks for the interest,

    As I said in my post beforehand....
    The machine is 4 years old, and has worked the same way since its journey with me.

    Can you explain me a bit more on the HV cap stuff ?
    I am ready to tear open this Adapter if some compelling solution is nailed down.
     
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Are you sure about this
     
  5. bhvm

    Thread Starter Active Member

    Jul 16, 2009
    53
    2
    Sure about?

    Laptop stability?
    Buzz since the beginning?

    Yes Sir to both!
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    You know I did write a huge reply to your thread and when pressed post I got an invalid thread, contact admin. :eek:.
    And to make things worse your thread disappeared and I really got frustrated that I lost the huge reply and I forgot what I wrote.
    So after contacting the admin fixed it. so here I go again.

    It takes a lot of effort ripping open a laptop adapter when there is no screws.
    Care should be taken not to damage the board inside.
    Most components like small HV caps a well hidden under heatsinks and bulkier components. It will be a pain the neck to get to them.

    There could be a couple of reasons for this high pitch noise.
    Like you said if it were there when brand new it could be a design flaw.
    And it also could be that the cap develop a fault after it was shipped.
    If design fault then it will take a lot of work to find the cap, and to make things worse it could be a noise suppressor snubber creating a fault.
    Snubber's are made up of Cap, diode and resistor combination and sometimes with inductors too. Inductor on the other hand could be a culprit, as loose core and weakened glue could cause the core to vibrate.

    But there major case is caps. So I will tell u about them for now.
    High Voltage caps a small ( mainly in 2 pin blue colored ) ones.
    Due hight voltage stress they tend to degrade and value changes over usage pretty fast. Premium components lasts longer, but every now and then a component batch will have a bad component or a poor manufacturing result and these will go bad and the whole assembly line where that component is used will create problems.

    Talking about ripping opening the adapter, it's up to you, if you care then go for it, and I can show you the components. But take great care in doing so as most of the time glue is used inside if no screw's are there, and the glue will tend to break the board if care is not taken.

    De soldering the component is another problem, if you don't have proper soldering iron, solder wick and good quality solder.
    I am saying this as these type of high power adapter's have ground planes and power planes which are laid through out a multilayer PCB, and they absorb heat damn fast than any normal iron can supply. So the solder will be semi molten and sucking and wicking the solder is impossible.
    You will need to practice this if you are new. And believe me a beginner will tend to destroy the PCB most of the time

    Next is the cap location, Most of the time there will be strong glue holding them in place and will be located underneath most heat sinks.
    You might need to take out the heat sink together with it's component to take out a typical component. This heat sink components are far by the worst to take out due the heat absorbing factor.
    And to make things worse the glue will be holding them really well, so you won't know if it the glue or unremoved solder that is holding the component, so by the time you find out, you would have ripped the cap. :).

    And last but not least, these types of adapter will be cramped with components really tight. But we'll never know once you opened it. do we? :cool:
     
  7. bhvm

    Thread Starter Active Member

    Jul 16, 2009
    53
    2
    I understand the pain when one looses carefully compiled bunch of information.

    I had issues with site yesterday too... Somehow, My IP address got banned from accessing the site... a quick mail to the admin brought things back on track.

    Else... thanks for the vast info on my topic.
    I forgot that the adapters have no screws! eekk!!

    I don't know if i'll rip this thing apart... as this is the only computer I have now.

    Some buzz makes into my audio output as well (headphone only), and ideas on that?
    Its lower freq buzz than one from the adapter...maybe its from a different origin.
     
  8. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Hmm!! My guess is audible HF in injecting into the audio preamp.
    And since it is audible you can hear from the speaker two.
    This definitely is a big problem

    I don't think it will take long now, since you said it is getting louder somewhat.
    The oscillation will tend to heat up circuit components causing excessive power dissipation and finally blowing them.

    I suggest you think of buying a new one and get your brain stormed with the old one.
    It will be a good experience.
     
  9. bhvm

    Thread Starter Active Member

    Jul 16, 2009
    53
    2
    Hmmm.......

    What did I say?

    The hummmm/BUzz is same since the birth of this machine....

    Stayed the same since 4 years, no Increase, No decrease...

    There's still a lot of life in this machine, esp since I upgraded it to 4GB of RAM, and DUAL 7200RPM HDDs in RAID 0.

    I guess i'll wait for a year more until spending on a new one.

    Thanks for all the help and time you gave me. I've learned a lot from you.

    Have a nice day.
     
  10. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Welcome.
    PS. I wonder when you will return with that adapter
     
  11. bhvm

    Thread Starter Active Member

    Jul 16, 2009
    53
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    The buzz goes away while heavy load is applied...Eg Playing Crysis.
    How come?
     
  12. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    It means the loading is causing the switching frequency to rise above the human hearing range.
    The adapter is definitely having a problem
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    Just a speculation - might be that when the power adapter was made, it did not receive a full "load" of epoxy fill, or their may have been an air bubble in the epoxy filler. That could have left some inductor windings unsupported, and they could be vibrating inside the adapter.

    At any rate, if the noise intensity has not changed, it's probably OK to keep using it - but not unattended. If the noise increases noticeably, stop using it.
     
  14. bhvm

    Thread Starter Active Member

    Jul 16, 2009
    53
    2
    Yeah...
    Thanks.
     
  15. bhvm

    Thread Starter Active Member

    Jul 16, 2009
    53
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    Hello again,
    I just Isolated the ground.
    Simpley taped the top Prong on the plug.. and the noise went away!

    Sometimes, My lap gives me a very small shock at the front speaker grill tough... Ohh!!
     
  16. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Cause now you are completing the earth loop
    u cut the ground, you stand on ground which makes you a solid ground and then you touch the grill which is connected to the lap chassis..
    After cutting it you are providing it.
    Way to go.....
     
    bhvm likes this.
  17. Audioguru

    New Member

    Dec 20, 2007
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    I think the power supply was designed by a deaf guy who cannot hear frequencies above only 3kHz and wrongly thinks most people cannot hear frequencies from 3kHz to 20kHz which is normal hearing. The deaf engineer attended too many rock concerts or drives a noisy motorcycle.
     
  18. bhvm

    Thread Starter Active Member

    Jul 16, 2009
    53
    2
    My Bodily Loop complete does not re-introduce the noise.
    Guess My body is good at looks but bad at Conduction ha ha ha ha.!
     
  19. bhvm

    Thread Starter Active Member

    Jul 16, 2009
    53
    2
    Copy that!!!!

    This used to introduce stray Noise into the audio Sub-Circuit!
    After investing sony MDR and Phillips 40mm (cans), this dilemma was extremely annoying.
    Now its GONE!

    BTW my ears are super sensitive... I can also 'hear' Cellphone chargers....CFL SMPS....PC SMPS....and so on...
     
  20. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
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    Wow, I wish I could hear them, I guess I stick with taste.

    And they dont taste like they sound. ;)
     
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