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View Full Version : Help needed please re: rpi2 and new psu



richie60
16-05-2019, 15:58
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-and-interfaces-for-raspberry-pi/audiophonics-i-sabre-v21-dac-es9023-tcxo-raspberry-pi-3-pi-2-a-b-i2s-p-11917.html

The psu: https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F 323781588105

Is there anything I need to do to the dac?

Bourneendboy
16-05-2019, 16:07
I'm talking rubbish, should have looked at the link:)

mikmas
16-05-2019, 16:19
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:

https://www.audiophonics.fr/23219-thickbox_default/audiophonics-i-sabre-v21-dac-es9023-tcxo-raspberry-pi-3-pi-2-a-b-i2s.jpg

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

Slightly similar case with the Allo Boss DAC.

Light Dependant Resistor
16-05-2019, 16:32
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

richie60
16-05-2019, 17:21
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:

https://www.audiophonics.fr/23219-thickbox_default/audiophonics-i-sabre-v21-dac-es9023-tcxo-raspberry-pi-3-pi-2-a-b-i2s.jpg

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...