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Chord Mojo DAC-amp ☆★►FAQ in 3rd post!◄★☆

Discussion in 'Portable Source Gear' started by Mython, Oct 14, 2015.
  1. harpo1
    Not to the mojo but possibly the headphones or iem's you have plugged in to it.
     
    Deftone likes this.
  2. musickid
    I would be more worried about connected headphones. If mojo plays nicely now then no problem. Unless of course the mojo ghost appears at 3am..........
     
  3. dakanao
    So this USB isolator (https://hifimediy.com/high-speed-usb-isolator-480Mbps) came yesterday, and tested it out for 1 hour. Plugged it in the USB port of my Jitterbug, with my Jitterbug again to my laptops USB port, with another Jitterbug sitting in another unused USB slot.

    I figured this would be the best setup, since I except there to be more RFI and EMI on the laptops usb than the isolator (obviously), so it would only make sense to connect the Jitterbug to the laptop, instead of to the isolator.

    But the result, wow. The Mojo became even more liquid, natural and smoother, with better separation and imaging, than with just the 2 Jitterbugs.

    Compared to using the Mojo directly to my laptops USB port with no Jitterbugs, and no isolator vs this setup, it really is a big difference.

    I encourage USB users to use this setup if you haven't already. It is a bit expensive, but if you want to experience the Mojo on it's fullest (or near fullest) potential, it is worth it. I have learned that there's so much noise from USB and RFI/EMI that I wasn't aware of, that takes away from the Mojo's capabilities.

    And yet this setup doesn't reclock the Mojo's processing in any way, so it has no downsides at all!
     
    Last edited: May 15, 2019
  4. Elecroestatico
    Reading all the battery issues mojo has I went ahead last night and opened mine. Just like everyone else I also found the battery super swollen, to the point that the last screws I took off popped out by themselves with the pressure contained inside the case. Like many off you Im also surprised that it did not damage the board as the presure was completely against the fpga chip and another large processor on the board. Battery is so swollen I cant even close mojo case back again without applying like 10kg of force on the case to get the screws to reach the hole threads. I guess Rob Watts is so lucky that such design flaw is not breaking the circuit board, at least in most cases, but at least they should charge or sell the battery replacement at cost, so as to honor a $600 dac that should not have these kind of problems.

    My mojo is running on optical and after testing a few usb chargers without the battery I get very loud pops and a static background noise. I see many people here taking the battery off and running their mojos in desktop mode without a problem. Is there a particular usb charger that needs to be used or maybe the problem is only with optical? Let me know if you know a fix! I tried .8amps, 1.2 amp and 1.8 amp chargers and they all make those loud dangerous pop noises for speakers.

    my version if mojo is 2016 with qr codes. board I think says rev. 4.xx
     
  5. Elecroestatico
    Actually I'm thinking it was my fault to have gotten those loud pops running in desktop mode. After removing the battery I placed a heat sink on top of the two big processors on the board, but I think the thermal pad that I used between the chips and the heatsink might have some conductor properties because after removing such thermal pad the mojo now works perfectly without battery.
     
  6. Deftone
    If i remember rightly, disconnecting the battery is ok for "line out" mode to an amp on a charger but for driving headphones directly the battery provides more power.

    Someone on this thread recently modded Mojo so that it was taking power from the wall but still providing the same output as the battery would have for headphone use.
     
  7. Elecroestatico
    loud pops and static noise is back again. I have found that the swollen battery has actuallly fracture the pcb board. I know this because if I apply enough down pressure to the fpga chip then the loud pops are gone, meaning that the battery as it expanded inside the case gradually micro fracture some of the threads and solder points in the circuit board due to the excessive pressure caused by the battery. (such fractures are usually not visible to the human eye). I have made a heatsinnk and therm pads in a way that enough pressure is applied to continue operating as normal without battery but I dont want to end up with a useless $600 dac that had only last me about a year of only home use (never taken outdoors). Does anybody know whats the warranty period for mojo in the USA? I bought from an authorized dealer, or can somebody from chord help me?
     
    Last edited: May 16, 2019
  8. Elecroestatico
    Well this is not the problem I'm having, but for what is worth I have noticed that without the battery the mojo looses a bit of its character, specially in the mid low frequencies, even without a headphone connected, I can hear this in line mode as well. Maybe this is in my head but for reference im one of the very few people that can detect the slight difference between the two 3.5mm headphone outputs in the mojo, even when they are connected to the same headphonne amp inside the mojo.
     
    Last edited: May 16, 2019
  9. miketlse
    Probably best to contact chord customer support, unless @Mojo ideas wants to propose a solution.
     
  10. dakanao
    Same here, can hear the difference as well..

    I can also hear the difference between an brand new Mojo, and a Mojo that had more play time. And a difference each time some RFI/EMI is eliminated due to a more shielded USB cable, extra Jitterbug and heard an extra improvement with an additional USB isolator.
     
    Last edited: May 16, 2019
  11. Deftone
    I wonder if the swollen battery problem issue is from people playing and charging while on low battery because i know it gets hot this way. Leaving it plugged in on a full charge its quite cool.
     
  12. Mojo ideas
    you really should not have taken the unit apart yourself the mojo should have been taken to your dealer for battery replacement
    Surprisingly the expansion of the battery is designed to occur if it fails as it rips the internal contacts off disconnecting the battery cells. Failure like this is rare it can happen if a unit has been exposed to high heat for very a long time .
    Batteries can be dangerous!!!
    so if you cannot take your unit to your dealer for repair . Do not try now try to put the expanded battery back into the unit.
    Very carefully unplug the battery there’s small white connector unplug it! do not puncture or squash the battery do not put it near combustible materials do not send it by post or carrier dispose of it safely such as temporarily burying it in sand then when you have time please take it to a battery disposal Centre such as like those at supermarkets or household waste disposal centres. Then contact info@ chordelectronnics.co.uk for advise on the battery’s replacement.
     
    Last edited: May 17, 2019
    miketlse likes this.
  13. betula
    Android/Mojo question:

    Mojo works fine with my android phone (Motorola), but it doesn't work with my Samsung tablet. I know, some phones/tablets don't support usb audio out, but I was wondering if there is a way around it. Usb audio from UAPP works perfectly on the tablet, but the system sounds (YouTube, VLCplayer) don't. I set the USB connection to 'audio source' in developer mode, without any success. I guess this Samsung tablet (running android 8) is not supported?

    Should I just accept the fact that I won't use Mojo for movies on the plane out of the tablet or there is a way around it? Rooting? Any thoughts? Thanks.
     
  14. Elecroestatico
    I have never taken mojo out of my house or place it in a hot area, so if it was exposed to high heat for a long time it could only be the heat that mojo generates. Battery was swollen and operational so those internal contacts in the battery did not detached. Yes I was careful removing the battery, I even got some latex gloves as I noticed the battery was oily, no visible spills, just felt oily. I'm no stranger handling electronics/computers/lenses, I even grounded my self so no static discharge would happen to the electronics, so unplugging the battery connector was very simple and yes I'm not thinking about putting it back. But if you read my second post you'll find out that the problem is really not the removal of the battery, it has more to do with the damage the battery did to the pcb board due to the excessive down pressure applied to the circuit board. I cant be 100% sure but like I said I have some experience with electronics and I have seen this problem several times in motherboards, so I can tell the mojo pcb board has been microfractured as the battery was pressing really hard on it, you can tell this because using a latex glove I can apply similar pressure with my fingers to the board and then the mojo works as it should, no more loud pops or static backgroung noise, as soon as I take my finger off the problem reappears. Unless such pressure is required by design I can't think of any other reason I'm having this issue. Please advise! and thank you for replying.
     
    Deftone likes this.
  15. dontfeedphils
    If the FPGA used in the Mojo is a BGA style package, then more than likely the solder joints have been fractured due to the stress from the battery. BGA solder connections fracturing is nothing new either (remember the XBOX 360 RRoD? That was caused by fractured solder joints on a BGA due to excessive heat).
     
    Deftone likes this.

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