TPA3122 Weird Problems

Discussion in 'General Electronics Chat' started by Casual_Engineer, Aug 31, 2014.

  1. Casual_Engineer

    Thread Starter New Member

    Jun 13, 2014
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    Hello everyone. I built a class D audio amp on a breadboard, however, I'm running into weird problems involving it.

    So I was following the following circuit. The only change I made was adding 2000uF capacitance to the DC bus. Keep in mind that the circuit draws around 10ma at 12V. However, the circuit randomly does not power up when 12V-28V has been applied.

    Another problem I realized is that when my audio signal exceeds 1vpp the circuit shuts off and the power needs to be recycled to work again.

    Can anyone advise me on how to correct the problem?
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    What supplies the 12-28V?
     
  3. Casual_Engineer

    Thread Starter New Member

    Jun 13, 2014
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    YH-305D, A 150W power supply (32V/5A)
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    The 1000 uF cap takes too long to charge up. If so, the device is latching up.

    Is the 1000 uF cap on your circuit bigger than the filter caps on your 5A power supply? If not, is your supply old or have high ESR filter caps?

    If you turn it off and then on immediately, does the device work?
     
  5. MikeML

    AAC Fanatic!

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    Does this supply have fold-back current-limiting, or possibly a crow-bar circuit?
     
  6. Casual_Engineer

    Thread Starter New Member

    Jun 13, 2014
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    It does, but I did not see it tripping

    I'm not sure what's the filter cap on the power supply. I brought it off ebay almost a year ago.
    I don't see it working when I turn it off then back on. I do notice the following

    1) The speakers make a chipping sound
    2) If I move the wire connecting the right speaker from pin 12 to pin 13, then reconnect it to pin 12, the amplifier becomes operational.
     
  7. GopherT

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    Well, now I would guess a wiring error. Send a photo of the board (Front and back).
     
  8. Casual_Engineer

    Thread Starter New Member

    Jun 13, 2014
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  9. GopherT

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    Nov 23, 2012
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    You have a mess of sorts there. Your positive (+) rails should be connected to each other (the yellow jumper on yhe bottom of tour board connects the left negative rail to the right positive rail. You need to really be careful, be consistent and follow the guidelines so you do not have to remember which is positive and negative, you just have to look at the blue or red rails on the breadboard.

    You may be aware of the positive/negative inconsistencies and that is fine for you but it become difficult or impossible to follow from a photograph. You might be best off being consistent, then I can help.
     
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  10. Casual_Engineer

    Thread Starter New Member

    Jun 13, 2014
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    Took your advice and also made a slight modification to the circuit (pic 1, pic 2). Yellow, purple, green and grey are ground. Blue, Orange, and red are VCC. Blue connects to the output LC circuit. Also, I placed a .1uF capacitor between pin 10/11, and pin 1/20 to see if it is a latching issue.

    Seems like the problems from earlier disappeared. I guess it had something to do with how close the decoupling caps had be for the IC. Hell I'm able to use the full volume from the computer without the circuit crapping out on me other than clipping problems.


    THANKS FOR THE HELP GUYS! :D
     
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