Trying to fix ESS based sound card, problems with amplifiers

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  • Paar
    Member
    • Jun 2020
    • 14
    • Czech Republic
    #1

    Trying to fix ESS based sound card, problems with amplifiers

    Hi everyone. I have a problem with my ES1868 based sound card, mainly with it's amplifier part. The right channel is crackling all the time, but only when amplified. When the card is set to LINE OUT, both channels work fine. I have replaced the amplifier chips with new ones but the problem persists (chips are two LM386N1). When there is only right amplifier installed the channel works fine but when there are both, the left is fine but the right crackles. Made some measurements - left amplifier outputs approx. 6V but the right one outputs 12V. The weird thing is that bot GAIN pins on the left amplifier have approx. 1.3V but with the right amplifier one of the chips has 5V-7V and the second one has around 3V and is changing constantly. Is it some voltage noise? Some kind of short? I am not very skilled in fixing audio circuitry so I am searching for help even though I know it's hard to help without having the card personally. The amplifier circuit seems very simple but I cannot figure it out. Has someone experienced something similar?

    I have replaced all electrolytics but that didn't help whatsoever. The problem had to occur by some HW malfunction or overvoltage as the card itself was unmodified when I got it. Where should I start?

    Tags: None
    • Paar
      Member
      • Jun 2020
      • 14
      • Czech Republic
      #2
      Re: Trying to fix ESS based sound card, problems with amplifiers

      It was a bad solder joint, after reflow the card works perfectly.

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