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Post-soldering August ep 650 headphones, bluetooth mode doesn't turn on. Any hope?

Discussion in 'Troubleshooting and Repair' started by NeoJesus, May 23, 2018.

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  1. NeoJesus


    May 23, 2018

    I have a pair of August ep 650 bluetooth headphones that I received as replacements of my original pair towards the end of my warranty, and my warranty has ended anyway. I try to be careful with these headphones but occassionally they receive a little bit of impact when they fell down a few times before and as they rub within my backpack.

    Previous Damage and Repair
    The left ear piece of the headphone had one of the wires (of one red and one black connecting the ear piece to the chip/board) break which made the sound only appear in the right ear piece of the headphone on both bluetooth mode and with the audio jack. The wire/cable was welded together at the breakage point and this fixed the problem. There was no specific damage

    Current Damage (Initially)
    However, the left ear piece stopped working again, but everything else worked including the bluetooth mode. Opening up the ear piece I found that the red wire/cable (of the one red and one black connecting the ear/sound piece to the chip/board) was detached from one of four openings of the chip/board; broken again.

    Note: On both bluetooth mode and using the audio jack played audio, just through the right ear piece. And the battery and everything worked as expected.

    Latest Repair
    The red wire/cable was welded to the chip/board on the opening from it was detached from, with some solder and flux - but somewhat messily. The broken tip of the red cable was put above a lighter flame (away from the rest of the chip/board) to expose more of the copper wire and burn away the insulator, and a big chunk of solder was used with repeated attempts of welding. Both a knife and a small screw-driver were used to ensure there is a gap between the soldered area and other areas.

    Final Damage (The Actual Problem)
    After soldering the red cable, the bluetooth mode wouldn't turn on. Using an audio jack worked and both ear pieces would actually work this time (the repair worked), but something else went wrong in that the bluetooth mode couldn't be enabled using the on/off button (and play/pause button).

    The blue/red lights function correctly when it comes to charging, but upon trying to turn on bluetooth mode by holding the ON button as is normal (with little and enough charge) neither the expected sounds are produced or the blue light turns on. (One exception is on some press & hold attempts - but NOT EVERY - both the red and blue lights flash for a short instant and stop immediately on the moment of pressing the ON button).

    Question: Any hope, any potential things I can try to solve & repair, or will I have to buy a new pair?

    Kind Regards & Thank You,

    Images (some with Annotated copies):

    20180523_203406.jpg 20180523_203406_2.jpg 20180523_203508.jpg 20180523_203508_2.jpg 20180523_203518.jpg 20180523_203552.jpg 20180523_203602.jpg 20180523_203602_2.jpg 20180523_203628.jpg 20180523_203703.jpg 20180523_203754.jpg 20180523_203754_2.jpg Untitled.png
  2. 73's de Edd

    73's de Edd

    Aug 21, 2015
    Sir NeoJesus . . . . .

    Excellent initial introductory information and visual presentation.

    Now, after perusing over the info, it seems like you were always a diddling n' a fiddling with the AF output stages connected circuitry and either leaving it unloaded or shorting it out.
    Now the whole system is responding with a no- go fault situation.

    Perusing over the 3rd photo down.

    We can see the units main custom microprocessor . . .a chugging along at 26 meggle-hurtz, with the smaller chip to the right assuredly being its support memory chip.

    Back to your power switch, to its right we see a single SM transistor, and at the top, above the switch is a dual unit.
    I would expect these to be POWER FETs with one of them related to switching the power to the ??? PAM R?8?9?0 G? power audio amplifier.
    That is being located at far left bottom.
    Do a better inspection of the numbering of that chip . . . as that is the best . . . that I am able to see.
    Then we look up that chip to find its power input pin, and lift it to then be able to have this chip power isolated.
    Then power up and see if the unit doesn't then stay on, with this pobably shorted chip . . . . then being out of the power loop circuit.

    I read one transistor as being a 3? B? G / sideways Y . . .see if you can make out and read the dual units #. GL ?

    Thasssssssit . . . .

    73's de Edd
  3. Alec_t


    Jul 7, 2015
    Is the 9th photo showing the Bluetooth module and its antenna? If so, how does power get to its two contact pads?
  4. 73's de Edd

    73's de Edd

    Aug 21, 2015
    Hmmmmmmmmmmmm . . . . .

    Look at photo # 2 where you can see it setting over there by itself, but it really goes over to he other side of the headset.
    Then look att photo # 3 where you see the little piezo beeper, at the right top corner AND a second set of RED and BLACK wires, just below, that fold around and go to the opposite sidee of the board.
    I would suspect that they are feeding the power for the BLUE -toofie modules, two gold contact tabs via pressure contacts aligned up with them.
    Looking at the right angle turn of the right power foil, that distance down to where the COB epoxy covers it up should be about right for 2.4 giggle-hurts, then the extra added loooooong serpentine coiled foil path could only be related to enhancing omnidirectionality aspects.

    Last edited: May 25, 2018
  5. NeoJesus


    May 23, 2018
    Thank you for the replies.

    Note: I don't really know much about electronics or much of this, so I wasn't too sure about some parts of your thoughtful replies - for which I thank you anyhow. I can and have used Google to find out some of the abbreviations to make a little bit of sense but I'll keep trying to see if these can be repaired and will try to provide any information that is necessary.


    If by 9th image you mean the tiny chip on the closing flap/casing then:



    Kind Regards,
  6. Alec_t


    Jul 7, 2015
    Don't try puncturing that thing with a needle: it's the microphone!
  7. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    This thread closed.
    Last edited by a moderator: Mar 25, 2020 at 6:30 AM
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