djevlen
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Choosing the correct DIGI+ Board. HifiBerry interrupting.

Thu Apr 21, 2016 7:39 pm

Hi

Ive made a new psu for raspberry pi 2 model B. The pi is only music player, and when i start the dishwasher or plug or unplug some other electric device from the wall socket or turn on the lamp, the pi stop to play music for a short moment..

How to solve this problem ? Was thinking to connect better/bigger capacitor, but with which value ?

Setup:

-Toroidal Transformer 30VA 230V -> 2x6V / 1x12V
--Rectifier
---Cap : uF2200 25V
----LM2596 Buck DC-DC Adjustable Step Down Power Supply Module Converter

any advice and suggestions will be greatly appreciated
Last edited by djevlen on Mon Jun 06, 2016 11:07 am, edited 2 times in total.

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davidcoton
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Re: diy powersupply interrupting

Thu Apr 21, 2016 10:12 pm

Have an electrician check your mains supply and wiring. It sounds like there could be a serious problem there. Only when that is checked and found OK should you consider an extra capacitor on your supply.
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rzusman
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Re: diy powersupply interrupting

Thu Apr 21, 2016 10:20 pm

Does the Pi actually reboot?

geoffr
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Re: diy powersupply interrupting

Fri Apr 22, 2016 12:22 am

davidcoton wrote:Have an electrician check your mains supply and wiring. It sounds like there could be a serious problem there. Only when that is checked and found OK should you consider an extra capacitor on your supply.
I would tend to agree - while I am not an expert on sizing a cap for smoothing the output of a rectifier, 2200uF is quite big, and going any bigger you probably would want to carefully consider issues related to inrush current.

Out of curiosity - why not use an off-the-shelf 5V DC power supply? That will probably be more efficient. The only case where I am looking at using a rectifier and Buck converter is for an irrigation controller where I need a 24VAC supply to control solenoid valves, and don't want a separate power supply for the Pi.

stderr
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Re: diy powersupply interrupting

Fri Apr 22, 2016 12:48 am

djevlen wrote:How to solve this problem ? Was thinking to connect better/bigger capacitor, but with which value ?
Setup:
-Toroidal Transformer 30VA 230V -> 2x6V / 1x12V
--Rectifier
---Cap : uF2200 25V
----LM2596 Buck DC-DC Adjustable Step Down Power Supply Module Converterd
Is this the TI part or is it something out of a street shop in China? Is this the right data sheet?: http://www.ti.com/lit/ds/symlink/lm2596.pdf . I noticed that it says not to use greater than 820uF caps and that ESR needs to be carefully considered as do issues with regards to the inductors.

mosespi
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Re: diy powersupply interrupting

Fri Apr 22, 2016 5:37 am

Good suggestions from everyone else. I would agree your cap is pretty large.

Are you sure it is a problem with your power supply? Can you swap the power supply with a regular USB and retest?
Can you give us more info as to what happens? Is "short moment" a few seconds? A minute? Does the Pi reboot?

Do you have your audio playing through (or sourced from) bluetooth, wifi or some other wireless? If so, I would guess possible localized RF blip/interference that causes a short pause in audio playback.

I've got a bit of experience with the LM2596, but we first have to confirm its a power problem before diving into switch mode power supply design.

Regards,
-Moses
Power problems? MoPower UPS for the Pi
http://www.allspectrum.com/mopower/

masa-aud
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Re: diy powersupply interrupting

Fri Apr 22, 2016 6:37 am

reply to djevlen on diy psu
I think that the 2200uF is too small to supply enough energy for the step down circuit to output constant 5V (2A) to your Pi from the rectifier (even a bridge type), apart from the cap at the output is restricted to less than 820uF e.g..
BTW I wonder why your psu is sensitive to other home electric machines. I recommend you to try changing tapping point for your psu to another AC outlet.

djevlen
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Re: diy powersupply interrupting

Fri Apr 22, 2016 10:02 am

Ive had off-the-shelf 5V 2A psu, and it did the same. Thats why I tried the DIY way.
The pi has a HiFiBerry Digi+ connected and its streaming to DAC via coaxial connection.

The interruptions last maybe 1 seconds, and then it resume playing music. no reboot.
The pi is playing from USB stick atached directly to it, or from NAS (no wfifi, only cat5 wires). The interrup happens no matter which source pi is playing from, as soon i turn on something in the kitchen , or lamp it stops for a moment. 1 second or so.

Oh and the capacitor is connected between the rectifier and step down buck. I was following this guide :
http://www.learningaboutelectronics.com ... supply.php

FM81
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Re: diy powersupply interrupting

Fri Apr 22, 2016 3:12 pm

First be aware on davidcotons hint:
davidcoton wrote:Have an electrician check your mains supply and wiring. It sounds like there could be a serious problem there. ...
When this is checked: Have you any spikes or noise or such on your 5V-line during the interrupt-events? (In best case please check this with an oscilloscope.)
If not: Is the effect gone away, when you have no external connections, means using the raspberry in a fully isolated environment?

MfG, FM_81
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davidcoton
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Re: diy powersupply interrupting

Fri Apr 22, 2016 5:27 pm

djevlen wrote:Ive had off-the-shelf 5V 2A psu, and it did the same. Thats why I tried the DIY way.
PLEASE refer to my original advice.

There should be no way that switching on another device (especially a small load like a lamp) should interrupt power to your Pi.

If you connect a lamp where the Pi normally plugs in, does the lamp flicker if you start the dishwasher?

I am an electrician, I fear you may have a poor or loose connection in your house wiring. This could potentially cause a fire.

PLEASE get an electrician to check URGENTLY.
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rzusman
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Re: diy powersupply interrupting

Fri Apr 22, 2016 7:41 pm

djevlen wrote:Ive had off-the-shelf 5V 2A psu, and it did the same. Thats why I tried the DIY way.
The pi has a HiFiBerry Digi+ connected and its streaming to DAC via coaxial connection.

The interruptions last maybe 1 seconds, and then it resume playing music. no reboot.
The pi is playing from USB stick atached directly to it, or from NAS (no wfifi, only cat5 wires). The interrup happens no matter which source pi is playing from, as soon i turn on something in the kitchen , or lamp it stops for a moment. 1 second or so.

Oh and the capacitor is connected between the rectifier and step down buck. I was following this guide :
http://www.learningaboutelectronics.com ... supply.php
If the Pi doesn't reboot, it's very unlikely to be a power supply issue.
Sounds like a possible ground-loop problem, or a glitch introduced on the coax cable.

djevlen
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Re: diy powersupply interrupting

Fri Apr 22, 2016 11:38 pm

rzusman wrote:
djevlen wrote:Ive had off-the-shelf 5V 2A psu, and it did the same. Thats why I tried the DIY way.
The pi has a HiFiBerry Digi+ connected and its streaming to DAC via coaxial connection.

The interruptions last maybe 1 seconds, and then it resume playing music. no reboot.
The pi is playing from USB stick atached directly to it, or from NAS (no wfifi, only cat5 wires). The interrup happens no matter which source pi is playing from, as soon i turn on something in the kitchen , or lamp it stops for a moment. 1 second or so.

Oh and the capacitor is connected between the rectifier and step down buck. I was following this guide :
http://www.learningaboutelectronics.com ... supply.php
If the Pi doesn't reboot, it's very unlikely to be a power supply issue.
Sounds like a possible ground-loop problem, or a glitch introduced on the coax cable.

Connected the pi to DAC via Optical link and there are no interruptions at all..only when streaming sound via coaxial cable..Hope not im damaging my DAC ???? looks like the problem is in the direction which rzusman pointed out.

masa-aud
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Re: diy powersupply interrupting

Sat Apr 23, 2016 9:16 am

reply to djevlen on psu
About the cap 2200uF, it seems the output voltage of the transformer such 6Vx2 not enough for the regulator to output firmly 5V at (2A), because the rectifier can show but only around 7.4V even at peak that will cause frequent 0V at the regulator output as 100Hz or 120Hz. If 12Vx1 is applied to the rectifier your psu will work properly. Anyway cheking voltages of your psu with a scope is recommended to clarify this issue and also of your AC outlet line too.

djevlen
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Re: diy powersupply interrupting

Sat Apr 23, 2016 10:27 am

tried to rewire transformer to 1x12 v (red and violet together) and white/black to rectifier.

It didn't solve the problem.

Here are the transformer specs : http://media.it-tronics.de/Datasheets/T ... 826006.pdf

rzusman
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Re: diy powersupply interrupting

Sat Apr 23, 2016 3:38 pm

It's NOT the power supply dropping out!

I don't understand why everyone is focused on that - if the power supply was dropping out, the Pi would reboot or hang.
The OP has already stated that this isn't happening.

stderr
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Re: diy powersupply interrupting

Sat Apr 23, 2016 3:59 pm

rzusman wrote:It's NOT the power supply dropping out!

I don't understand why everyone is focused on that - if the power supply was dropping out, the Pi would reboot or hang.
It's some kind of interference or grounding problem or whatever, it's not a whole house cut in power that's killing the pi, although there certainly could be a pause in power due to a house wiring problem.

But he didn't start out saying that normal store bought power supplies have the very same problem. This interference could be caused by a Marconi spark gap generator in the poster's wiring, thus the person who said he's an electrician's concern. I wonder if AM radios work within a few miles of his house.

But the original poster never has explained what he means by the sound output pausing for a second. Obviously it isn't rebooting the pi if it comes right back. Is this "pause" accompanied by crackling and snorting out of the speakers like he's being hit with a lightning strike? Or is it just dead silence? Is the pi networked with ethernet when all this fun stuff is happening? I would operate without such a thing as a test.

He said:

"Connected the pi to DAC via Optical link and there are no interruptions at all..only when streaming sound via coaxial cable"

Is the pi perhaps output to a stereo or amp or something like that via coax somehow? How does that work? I would just have the pi and its power supply, no ethernet or professional sound system, just the bare board and some battery powered speakers. Does the problem still exist? I guess I would've done that before trying to home brew my 5v power source.

FM81
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Re: diy powersupply interrupting

Sun Apr 24, 2016 6:38 am

I'm a little bit sure too, there's something wrong with the ground-connections! To to the raspberry (and it's included DAC) of our thread-opener may exist two or three:
- over the shield of the LAN-cable
- over the ground of audio-signal
- via the self-made power-supply
There seems to be a potential-difference between them which shouldn't be there ...
With an optical connection all things seems to be fine?
Means for me that the potential-difference may still exist, but because there is no electrical way back to the raspberry anymore, it doesn't matter ... :)

Greetings, FM_81

PS: And in general: for audio ist ONE GOOD ground enough, of course it should be on the right place too ...
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davidcoton
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Re: diy powersupply interrupting

Sun Apr 24, 2016 8:21 am

The fact that the system works without a glitch with an optical connection does point to the involvement of a ground loop. But an ground loop problem should not be revealed by switching other mains appliances, unless there is a separate mains wiring problem. This is my last attempt to convince the OP to get his/her wiring checked. But I would hate that ignoring these problems could lead to a preventable house fire, or worse.
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djevlen
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Re: diy powersupply interrupting

Tue May 17, 2016 2:53 pm

update on the issue

Found out that the pi does not pause for a moment only when something else is turned on. It also pause when other device is turned off. For example: it will pause when i turn dishwasher or lamp off...sometimes when on.

djevlen
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Re: diy powersupply interrupting

Tue May 17, 2016 4:42 pm

updtate again

connected other amplifier to the pi with its 3.5mm jack stick = 0 problems
connected through hifi-digi optical = 0 problem
connected through hifi-digi coaxial = problem
Tried to remove ground from main line/cord to preamp = no difference

The preamp has 3-pin C13 plug and it is grounded. So i tried to connect it to power-line where ground is disconnected..no difference. The Pi paused for 1 second.
So my power-supply is OK..It did that also with stock pi power-supply.
This only happen with coaxial connection.. and i don't know if its the hifi-digi board coaxial connection that stops sending signal for a moment or if its the preamp fault. I don't have other coaxial devices so i cant test it.

djevlen
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Re: diy powersupply interrupting

Tue May 17, 2016 5:39 pm

ok, last update

Had one of these laying around :
https://img.conrad.de/medias/global/ce/ ... FB.EPS.jpg

Result : no interruption at all via S/PDIF
But can this be some incompatibility ? because the digi+ board is the "transformer version"
https://www.hifiberry.com/product/hifib ... r-version/

When i measure it with multi-meter @ "diode" setting it show short-circuit.

What can be the problem ?

Could my preamp (nuforce AVP-18) be over sensitive, or some Ground differences ? the funny part is that there are no problems when optical ports are used. Or is this just some anomaly that i just have to accept ?

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davidcoton
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Re: diy powersupply interrupting

Tue May 17, 2016 7:04 pm

Sorry I can't answer your main problem.

BUT you should NEVER disconnect mains ground connections. Mains ground is the main safety connection, breaking it will remove the protection from power supply faults in the equipment. The consequences can range from increased damage to connected equipment (including the Pi) to death by electrocution.

If there is a hum problem, a quick test is to break a signal ground. The solution may not be that; it could be to use the optical connection, or to design a proper earth break by transformer or other means.
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djevlen
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Re: diy powersupply interrupting

Mon Jun 06, 2016 11:00 am

Hello
Just wanted to report that the problem has been sovled :)

I have tried to get line conditioner..it didn't help.
I had electrician in my house to measure the sockets..no faults found..
I bought a new cd transport and connected to the preamp.No problems.
Tried with another music streamer..no problems.
I bought new pi and new digi+ board..same problem.

Then i contacted the DIGI+ company from Switzerland and got this reply:

"looking at this picture of the inner parts of your preamp it seems that the case of the preamp is connected to the ground wire, but not the circuit itself.
In this case, the isolation of the transformer works like a big antenna and can create problems like this. You need to use the transformer-less version.

Best regards,
Daniel"

So i ordered digi+ without transformer and all problems are gone. :mrgreen:

Thank you all for suggestions..hope this will help others choosing the correct model from the very beginning.

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