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Thread: Help needed please re: rpi2 and new psu

  1. #1
    Join Date: Nov 2012

    Location: Barry, Vale of Glamorgan

    Posts: 36
    I'm Richard.

    Default Help needed please re: rpi2 and new psu

    I've successfully been using an rpi2 with an Audiophonics v.2.1 dac for a while now no problem.

    Just got a linear psu from eBay to power the dac and pi, but it doesn't seem to be powering up with it.

    My understanding is that this dac takes the power and also feeds it to the pi.

    I've tested the psu and it works fine.

    The dac: https://www.audiophonics.fr/en/dac-a...s-p-11917.html

    The psu: https://rover.ebay.com/rover/0/0/0?m...2F323781588105

    Is there anything I need to do to the dac?

  2. #2
    Join Date: Apr 2012

    Location: Near Oxford

    Posts: 911
    I'm Bill.

    Default

    I'm talking rubbish, should have looked at the link
    Allo Boss Player / NJC Audio Reference Headphone Amp / Sennheiser HD600

  3. #3
    Join Date: Dec 2014

    Location: UK, East Midlands

    Posts: 1,471
    I'm Mike.

    Default

    Quote Originally Posted by richie60 View Post

    Is there anything I need to do to the dac?
    My French is not the best but if I'm right there is something on one of the illustrations that could imply that a jumper is needed if you want to use the DAC power input to feed the RPi as well:



    If you feed it via the RPi this is not required (I think)

    Slightly similar case with the Allo Boss DAC.
    If you don't like my potatoes - please don't dig up my vine!

  4. #4
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 1,348
    I'm Chris.

    Default

    It appears the DAC requires 5 volts DC - is that the voltage being output from your psu ?
    With DC fittings and cabling be aware of polarity, that the device being connected to that
    ground connects to ground and 5 volt positive to 5 volt positive. noting cabling or indeed the
    end plugs can be arranged to swap polarity. it is a jumble dealing with DC Also be aware of cables
    that swap that polarity at junctions.

    It is almost mandatory for equipment manufacturers to fit known plug types but some
    disobey the obvious common polarity of having positive as centre and do it the opposite way.
    Equipment manufacturers also should fit protection diodes or have circuitry unable to process
    current where wrongly connected.

    Its hard to determine if each end is positive to the centre conductor. or what indeed is expected
    - perhaps there are markings on the rear panels. I would begin carefully looking at
    each devices instruction manuals. In future to save this difficulty choose equipment accepting a AC voltage
    rather than DC

  5. #5
    Join Date: Nov 2012

    Location: Barry, Vale of Glamorgan

    Posts: 36
    I'm Richard.

    Default

    Quote Originally Posted by mikmas View Post
    My French is not the best but if I'm right there is something on one of the illustrations that could imply that a jumper is needed if you want to use the DAC power input to feed the RPi as well:



    If you feed it via the RPi this is not required (I think)

    Slightly similar case with the Allo Boss DAC.

    Thanks. All sorted now (No thanks to Audiophonics). I managed to dig out an old jumper from the back of an old CD Rom drive i had and connected it across the pins: 5v and external 5v as illustrated in the picture. The rpi then lit up��

    I have the psu set at 5.04v just to give it a little bit extra. Seems to work fine now.

    Thank you...

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