[arm-allstar] One of two USB URIs dropping off

[David McGough]

Agreed. This is probably a good area for a how-to. Who would have ever 
guessed that obtaining a solid and reliable 5V power source could be such 
a challenge!

BTW, I did a little write about 3B power woes over a year ago.  It's worth
reviewing. The executive summary is that the micro-usb connector is a
problem---you'll end up with ripple on the 5V supply due *ONLY* to CPU
load! And, this noise can potentially modulate analog hardware hanging off
the USB bus.

http://lists.hamvoip.org/pipermail/arm-allstar/2017-December/006939.html

73, David KB4FXC




On Sun, 13 Jan 2019, "Randy Neals via ARM-allstar" wrote:

> Perhaps your power config needs to be one of the "How to guides" on the
HamVoip web site.

I was totally against having an adjustable power supply, for the reason
that it is likely to get misadjusted.
Given what I've learned about power and the Pi 3B+, I'm much more inclined
to have an adjustable PS now to overcome losses/drop.

-Randy

On Sun, Jan 13, 2019 at 5:27 PM "Doug Crompton via ARM-allstar" <
arm-allstar at hamvoip.org> wrote:

> Randy,
>
>  While the adapters you mentioned from Amazon are very handy since they are
> plug and play we have had several failures and in other cases as you
> experienced low voltage since they have an output voltage of 5.0 (or maybe
> a little less) that is not adjustable, We also have no idea what it is that
> fails since it is impossible to take them apart! My theory is possibly heat
> build up since they never get even warm to the touch. This tells me there
> might be a heat transfer issue.
>
> In any event if you have one and it is working for you fine but if you are
> having problems that would be the first thing I would suspect and replace.
>
> We have been using a 5V open and adjustable buck converter like this:
>
>
> https://www.amazon.com/eBoot-LM2596-Converter-3-0-40V-1-5-35V/dp/B01GJ0SC2C/ref=sr_1_3
>
> and they work fine. We generally adjust to 5.2 volts at the board with
> minimal distance to the Pi and connect to the GPIO pins not the micro USB.
> At less than $2 each how can you go wrong.
>
>
> *73 Doug*
>
> *WA3DSP*
>
> *http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*
>
> On Sun, Jan 13, 2019 at 8:16 PM "Randy Neals via ARM-allstar" <
> arm-allstar at hamvoip.org> wrote:
>
> > To close out this thread with the solution.....
> >
> > 1. We were using DC to DC converters with a micro USB plug on the output.
> > Similar to these from Amazon. https://www.amazon.com/dp/B00KKI4C1U
> >
> > 2. There was also a "warbling" in the repeater audio which we did not
> > immediately notice, but which became apparent later.
> >
> > 3. Another ham had a different brand DC DC converter, similarly
> > encapsulated.
> > We connected that and after a few minutes we had a low voltage error.
> >
> > 4. We substituted a generic 5V AC wall-wart power supply, and the
> repeater
> > has been running steady for more than 12 hours at this point.
> > There is no warbling in the audio and no low voltage errors being
> recorded.
> >
> > Theory:
> > We obviously had a low-voltage condition on the Raspberry Pi. I did not
> > believe that was likely given that it used to work fine, and trying
> > different power supplies didn't seem to make a difference.
> > The voltage was drooping to lower than 4.6V at the input to the Pi Volt
> > Regulator.
> > The CM108 in the DMK URI has a 4.5 to 5.5 volts operating range. The low
> > voltage on the Pi would be even lower by the time it extended across the
> > USB cable to CM108 in the URI.
> > Voltage supplying the URI/CM108 likely sagged to <4.5V and we lost the
> URI.
> >
> > Randy
> >
> >
> > On Sat, Jan 12, 2019 at 7:11 PM "David McGough via ARM-allstar" <
> > arm-allstar at hamvoip.org> wrote:
> >
> > >
> > > Hi Mark,
> > >
> > > Yes, that style power supply is available from many sources. And, it's
> > > becoming the "preferred" variety for me, too, at this point.
> > >
> > > At least if it's not potted in epoxy, the manufacturer can't hide what
> > > components were used!
> > >
> > > I've also soldered power wiring to all my production RPi boards. I
> don't
> > > use the micro-usb at all.
> > >
> > >
> > > 73, David KB4FXC
> > >
> > >
> > > On Sat, 12 Jan 2019, "Mark G Thomas via ARM-allstar" wrote:
> > >
> > > > Hi,
> > > >
> > > > I use these cheap tiny adjustable DC-DC supplies, just a couple
> dollars
> > > each on eBay, fed with 12-14 VDC. So long as your 5V wires are short
> and
> > > heavy to minimize resistance and hence variation with load to the Pi,
> you
> > > can then adjust the supply up to sufficient voltage (possibly as high
> as
> > > 5.2-5.4 – I should measure...) that you measure 5.0 or 5.1 volts on
> the
> > > test point directly on the Pi PCB. Google for where exactly to measure.
> > > There is a poly fuse and maybe other sources of voltage drop on the Pi;
> > > hence the need to use a greater than 5V supply, especially on the more
> > > power hungry 3B+! This works great!
> > > >
> > > > My experience was the fixed voltage epoxy potted 12V-5V converters
> are
> > > too low voltage an output when under load, considering the resistive
> loss
> > > of the 3B+ setup.
> > > >
> > > > KC3DRE
> > > >
> > > > Mark G Thomas
> > > >
> > > > I am not sure if the photos will make it:
> > > >
> > > >
> > >
> > > _______________________________________________
> > >
> > > ARM-allstar mailing list
> > > ARM-allstar at hamvoip.org
> > > http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
> > >
> > > Visit the BBB and RPi2/3 web page - http://hamvoip.org
> > >
> > _______________________________________________
> >
> > ARM-allstar mailing list
> > ARM-allstar at hamvoip.org
> > http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
> >
> > Visit the BBB and RPi2/3 web page - http://hamvoip.org
> _______________________________________________
>
> ARM-allstar mailing list
> ARM-allstar at hamvoip.org
> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>
> Visit the BBB and RPi2/3 web page - http://hamvoip.org
_______________________________________________

ARM-allstar mailing list
ARM-allstar at hamvoip.org
http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar

Visit the BBB and RPi2/3 web page - http://hamvoip.org