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PCM1681: sound problem

user5896361
Prodigy 60 points
Part Number: PCM1681

I got Onkyo htr558b has digital output problem, when I start it after a day I get every sourse playing sound, after 5 to 15 minute the problem is that it has no sound in dsp mode, in direct mode i am getting sound without digital source, when i am playing file from usb or any other digital source i am not geting sound in even direct mode also, so i open and investigate where is the problem, i checked the dac chip when i am touching on DAC chip (PCM1681) i am geting distorted sound, then i checked digital input pins with oscilloscope I found frequency on 6,11,12 pin. also i found just now when i am touching (not the pin only top black part of the ic) the pcm1681 i am getting distorted audio also sometimes clear sound for few seconds. I found someone online who has same problem then he change ic and his problem solve. In my case if I order the ic I will get it after 40 to 60 day and It cost me too much,

Any way other way to fix this? Help pls

  • 0
    TI__Guru 53923 points
    Hi,

    You might want to check with Onkyo support to see if they have a fix for this. Generally if physical manipulation of electronics fixes a problem, then I could be a build or mechanical issues with the board. You could check for bad or cracked solder joints on or around the device. If you find one, you can try to resolder the joint or pin. Otherwise, you could try replacing the device, but the issue may not be the PCM1681, but some other components around the device.

    The digital source signal should be present on pin 5, 6,7, 8, and possibly 11, 12,13 depending on the configuration. Pin 17, 23 are the VCC supply pins, and they should should have 5V applied to them. Pin 9 is VDD, and should have 3.3V. The VCOM pin 25 should measure about 2.5V, and is generated by the PCM.

    If you find an issue with these pins, it might give you guidance on the circuitry that could be causing the problem

    I believe if you purchase the device from ti.com it should be able to get to you faster than that!

    Thanks,
    Paul
  • 0 in reply to Paul_Frost
    Prodigy 60 points
    www.badcaps.net/.../showthread.php exactly same issue, his problem solved by replacing pcm1681 may be it will solve my too. i am from Bangladesh and there is no onkyo support. at this moment i have no pay pal or international credit card to buy this pcm1681. so im in a great problem to buy this ic. that why i am searching alternative solution
  • 0 in reply to user5896361
    TI__Guru 53923 points
    Well it is possible the device is damaged, but I think you should try the debugging steps that I suggested before replacing the device. This could just be a small soldering issue.

    Thanks,
    Paul
  • 0 in reply to Paul_Frost
    Prodigy 60 points

    thanks for fast reply. i will post the result after trying debugging steps that you suggested

  • 0 in reply to user5896361
    TI__Guru 53923 points
    Okay, sounds good.

    Thanks,
    Paul
  • 0 in reply to Paul_Frost
    TI__Guru 53923 points
    Any updates?
  • 0 in reply to Paul_Frost
    Prodigy 60 points

    i am little bit busy this week, report you soon. in that time i was trying to brought pcm1681pwpr from tistore but i faild 6 times. i was using my friend American express credit card. it shows around 6$ for 2 ic+7$ for shipping. every time i tried it shows problems occur. his card provider tlod him he can buy anything from international online store. i dont known where the problem. i was mailed ti support but they told me it not there problem.  i search online and found some same ic in aliexpress.com the prices also lower then tistore! are those duplicate? or made by some other company?? any ideas about this?

  • 0 in reply to user5896361
    TI__Guru 53923 points
    I am not sure about the difficulty you are having ordering the devices from the TI store. I do not suggest you by a replacement from aliexpress. You could try one of TI's authorized distributors in Asia.
    www.ti.com/.../distributors.html

    In the mean time, let me know how your evaluation of the supply pins goes.

    thanks,
    Paul
  • 0 in reply to Paul_Frost
    Prodigy 60 points
    here is the debugging result. pin 17, 23 have 5v pin 9 has 3.3v pin 5,6,7,8,11,12,13 have digital signal when its 5.1 mode. chk all solder joint and all electrolite caps look fine. test the analog audio out pin (19,20,21,22,26,27)by cannecting extranal audio source to those pin, all channel sounding fine. what to do next? thanks
  • 0 in reply to user5896361
    TI__Guru 53923 points
    If you have been able to track down a schematic for the system you could try to confirm the digital values are correct. Otherwise you could still try replacing the PCM1681 device.