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3.3V Power Draw

Murat

October 02, 2017 04:43

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I am powering the 3.3v of the Digi+ Pro rev 1.1 separately using 2x26650 LiFePO4 batteries with fantastic results. The tonal balance improved tremendously; airiness came back with total midrange richness and impactful bass. I urge anyone with basic soldering skills to give this a try.

I have noticed, though,  that the RPI3/Digi+ Pro combination continues to draw current from the battery even when I disconnect the power from the 5V header. 

I found this surprising because the power LED of the RPI is off but the 3.3v circuit seems to be active drawing power like business as usual. 

1. I would like to know if this is normal.

2. Can I prevent this from happening by bending some pins or whatever? 

 

Thanks in advance & pls try the LiFePO4  goodness.

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6 comments

• 0
  
  HiFiBerry team October 02, 2017 08:38

  Hi,

  if you use separate power supplies for 5V and 3.3V it is normal, that they are separate. Disconnecting one power doesn't mean the other does not draw any power. You can't prevent this. 

  Best regards,
  Daniel

• 0
  
  mike mears October 02, 2017 12:06

  Hi Murat,

  I tried to do this mod and it did not work. With the mod, Volumio could no longer see the digi+ pro.

  I am using RP3 & the text on the digi+ pro board says "HifiBerry Digi-Pro HW 1.2." I see you are using rev1.1 I wonder i that makes a difference ?

  Apart from that I just removed R3 & soldered pins to the P5 header pads and like you, used batteries.

  Can you see any difference between what you & I did ?

  Best Regards

  mike

   

   

• 0
  
  Murat October 02, 2017 12:17

  Hi Mike,

  Can you try the following:

  1. Disconnect both the 3.3v & 5v

  2. Power the 5v first (no power at 3.3v yet)

  3. Connect the 3.3v immediately (i.e.within 1-2 seconds)

  Pls let me know if it works.

• 0
  
  mike mears October 02, 2017 13:01

  Hi Murat,

  Just tried as you suggested but it still not work.

  Funny thing is that when I remove the 3.3V battery supply, with R3 removed I am still measuring 3.3V on the header pins.

  BTW, when I revert to normal supply arrangement - everything works OK again so I think the digi+ pro board itself is OK.

  I wonder if this mod is valid for rev 1.2 

   

   

   

• 0
  
  Murat October 02, 2017 15:30

  i think people with HW 1.2 boards have also removed u2 as per this thread. https://support.hifiberry.com/hc/en-us/community/posts/211820549-3-3v-power-to-Digi-Pro

  better ask daniel.

  Rgds,

   

• 0
  
  mike mears October 02, 2017 17:55

  Hi Murat,

  Problem solved !

  It turns out that in standard unmodified format, it was not necessary to enable I2S in Vulumio for everything to work. However, after doing the mod enabling the I2S becomes compulsory. This is now done.

  
  So all is working well new & sounding pretty good !

  Thanks for your help

  mike