Total Bithead repair

  1. suicidal_orange
    I have just stumbled across my first portable amp - a Total Bithead. I used this daily for about 6 months with my ipod, but barely used the DAC part (I did test it worked before stuffing it in a bag).

    Today the DAC only has sound out of the left channel but using the line in both channels work, so somewhere between the PCM2900 and AD8397 the right channel gets lost. I've got it apart and everything looks fine but I can only get access to one side of the PCB which might not be helping.

    Can anyone help me with which pins are audio out (specifically right, if it's standard...) or confirm that the dot on the chip is at the end with pin 1? Any other advice would be appreciated, this will be a good learning experience before my next build (the CK²III was too easy, didn't learn any debugging skills [​IMG])

    Thanks in advance [​IMG]
     
  2. Fixz8
    Yep, the dot on the chip package marks pin 1. It's pretty universal, although some chips might have 2 or more marks, which makes it kinda ambiguous sometimes. You can usually double check by finding which pins are supposed to be the positive voltage supply and ground, and then just make sure those are reading right.

    I'd say make sure everything is soldered down on the chips in question, one of the pins might have come loose after enough vibration/shock.
     
  3. mgrewe
    This happened to me last week. The amp fell on the floor and when I powered her up, I only got the left signal. I ended up just blowing in it a few times and after a few days of off and on working, it started going again 100%. Good thing too b/c I have no access to a solder iron or any tools here at school.
     
  4. suicidal_orange
    Thanks for the help [​IMG]

    As I say everything looks fine, but no harm can come from blowing on it so I'll try it. The PCM9200 only has one dot so thats something, I'll get back to measuring tonight. I hope it isn't a loose leg as its a small chip, with very tight spacing - I have an iron, but my SMD skills aren't up to anything this small!

    Can anyone make sense of the pin names as relating to audio? So many legs [​IMG]

    Thanks again,

    Suicidal_Orange
     
  5. maxslug
    Bringing back this zombie thread because I just had to make a repair to my Bithead, and figure others might come across it.
     
    Symptom:  the right channel is very very weak or not present
    Problem : The PCB trace (circuit board wire) blew off the board!!!
    Fix: Add a wire where the trace was going.
     
    I don't have image permissions yet, so here's the pic of the fix : https://www.dropbox.com/s/8f5bi95zuqcvff8/total_bithead_repair.jpg?dl=0
     
    Under a magnifying glass I noticed there was damage to the board at the spot where the solder points to in the picture.   With a ohmmeter I still read low resistance (good) but the trace was obviously blown.     That makes sense for the symptom of very low volume on the right side.   I added a wire to two points on the same trace that bypassed the broken part et viola!
    Enjoy,
    -m
     
  6. HiGHFLYiN9
    Well done! Always nice to repair electronics that would otherwise end up in a landfill. Hope you get many more years of usage out of it.
     
  7. flamerz
    I have the same problem that maxslug. Does anybody know how to open this thing up without breaking it?
     
  8. foxa
    Last edited: Nov 16, 2017

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