Question about Akai LCT2715 27 in. LCD Television

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Power Supply Buzz

TV was given to me dead. I removed and recapped the 200W power supply using good 105 degree C capacitors. Most of the old caps were shot. TV now works fine. Unfortunately, it has a loud buzzing that appears to be coming from one (maybe both) PQ3220-1000C transformers.

Would you have an idea of what other component(s) might still be defective? I see no other visible damage to the power supply.

Thanks.

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  • gehdiving Nov 13, 2008

    Thanks for your response.



    Yes, all caps were replaced with the same rating, with the exception of two 470uf 25v, and two 470uf 16v caps. They were replaced with four 470uf 35v caps as 25v and 16v were not available from my supplier. My understanding is that this should not be a problem??



    Polarity of all the caps is confirmed as correct.



    There were also two bad 1000uf 16v caps on the TV main board next to the power connector. They were replaced with 1000uf 35v caps.



    I have seen numerous reports on the web of these power supplies buzzing in brand new sets. Most returned under warrenty.



    Interesting that you have never run into the buzzing problem.I recapped another of these same power supplies about a year ago and that one buzzed too. That set went in the trash can because of a bad display and no sound.



    If you think the four higher voltage caps that I used are a problem, I can track down ones with the lower rating and change them. Let me know what you think.



    Thanks again.

  • gehdiving Nov 14, 2008

    Unfortunately, I don't know whether the supply buzzed prior to the recap as the set was given to me dead.



    Any suggestions as to what you consider good quality capacitors and where to obtain them?



    Thanks.

  • gehdiving Nov 14, 2008

    Thanks. I'll give some thought to recapping it again.

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Did you use the same as original replacement capacitors? I have repaired many of these power supplies for others and never had an issue. It is possible that the failing capacitors could have caused more damage to the power supply but I have never seen it in over 50 repaired AKAI power supplies. Also, make sure you replaced the capacitors with the proper polarity.

Posted on Nov 12, 2008

  • Vernon Gibson
    Vernon Gibson Nov 13, 2008

    While this shouldn't be a problem and I have even used higher rated caps in the past when I did not have an exact replacement it could not hurt if you can to replace those with exact matched caps. I also suggest using high quality capacitors as I have seen issues similar to this arise by using low grade components. If the power supply did not buzz prior to the original capacitor repair I would think that it may have been a result of the cap replacement or damage sustained from the power fluctuation that the failing caps would have caused. If it did buzz prior to the repair I would suspect something on the AC side of the board that is causing this.

  • Vernon Gibson
    Vernon Gibson Nov 14, 2008

    Nichicon is what I buy about 90% of the time. From what I have seen they are a pretty good manufacturer for quality components and I have never had anything fail that I have used them in. Most capacitor manufacturers have a Premium line and they have a bottom dollar line... In some cases the old adage "you get what you pay for" is true. But, Nichicon tend to be reasonably priced and they are from what I have been able to determine good quality.



    I buy a lot of parts from Digi-key.com as they have quick shipping and good prices for most parts. Their site is not the easiest to navigate but they have pretty much anything you will need.

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