Avoiding Zynthian power down failure


Hello @ll,

yesterday I had a really stupid problem in the rehearsal room: shortly before the rehearsal I tested my Zynthian at home: everything was running. But apparently I disconnected the power supply too early and I had to notice that the SD card was no longer readable at rehearsal room.

This problem is not good for live performances. Unfortunately there is also an unpredictable power failure live…

My first idea was to design something with some goldcaps myself, but no: there is already such a solution. Admittedly: not cheap, but ready for it and well thought out: https://juice4halt.com/products

I’m thinking about buying something like this and hope it still fits into the Zynthian v2 case.

Does anyone have any other ideas?

Regards, Holger

Using overlayFS for read-only SD cards

Hey, I’m new to this world and I’ve been reading a lot these days. Somewhere I read you can have two sd cards, so you can have a backup sd card ready if it gets corrupted.

Hope it helps!


Hi @tocatdelala,

welcome to the wonderful and amazing world of Zynthian :slight_smile:

Yes, a second SD card may also solve this problem, but I won’t start searching and replacing a SD card on stage…

Also you have to keep in mind to copy the sd card regularly to have the same configuration on both cards…

Regards, Holger


hey! thank you

No, I mean an actual device that has two SD cards plugged and you can switch back and forth


Ai can’t see the price in the shopping cart on my android tablet. I wonder if it might help with loud xruns with hifi amp2?


Hm, I thinks that this will not work. The problem is, that buffers are not written to the filesystem when powering down hard. So, if they are not written to one sd card they won’t be written to the other, too (IMHO).


Hi Holger,

have a look at this:



Probably something like this would be more use. https://learn.adafruit.com/read-only-raspberry-pi?view=all.

Boot the in Read Only mode for gigs and read-write for making snapshots and remember to shutdown cleanly. Record to external USB. Possibly holding down one of the four switches on boot to select rw mode?

That and making it work with X11…

Alternatively using Overlayfs which is used in docker containers. https://www.domoticz.com/wiki/Setting_up_overlayFS_on_Raspberry_Pi Which looks to have a sync down option.


Hm, yes. Much work and the big question is: If this will work, will it be used for the Zynthian image or do I have to create my own Zynthian image for every new version… So I think I will go the hardware way.

Regards, Holger

Model			Qty	Price		Amount
J4H-5V-USB		1	39.00 EUR	39.00 EUR
Subtotal					39.00 EUR
Shipping					6.60 EUR
PayPal fee					2.28 EUR
VAT (19%)					9.10 EUR
Total						56.97 EUR

The estimated delivery time is 1-3 weeks.

Hmmm… The problem will be to get it inside the case. Or I have to build a new case… so I can think about my next Zynthian integrated directly into a keyboard… perhaps the v3? :smile:

Regards, Holger


To avoid similar situations, now I always carry a cloned copy (or two) of sd cards. Regarding the power, I switch from micro usb to more reliable connector (and more reliable power supply that can give actual 3A when needed).

Also, my problem was having no good ground in some performance venues, so there was hum and noise in some places. So I thought of an idea to use ferrite rings - old school way in case we use power supply. Battery power is also a nice solution imho.

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There is rather a nice feeling to doing it completely off grid …


My solution exactly.


Look what’s just turned up!


Whoaaaaaa!!! And? How many years you can make music without connecting to a power source?


I’ve got to put in on first…
What with all the different power supplies round this Pi I’m expecting a fairly substantial bang at some point… :smiley:


Strange they use 2.7V capacitors. One of those would avoid a 0.5V drop of a 2A load for approx. 22 seconds (if my O Level physics is remembered) so I would guess it can support about 10s outage before things go off. I will be looking at a Li-ion batter backup so as to have full UPS and portable power.


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The stupid mobile app cut away all the post text :frowning:


I use this board in other installations where I need an “UPS” for rPI. Never had a problem… it can talk with rPI on I2C, so it should be not so hard to integrate it (or something similar) in Zynthian system.


I’m planning on something similar to the Pi UPS @Axeman is using for the live rig I’m building. I like the Juice4Pi solution, but it’s expensive to get it in the US, and it does appear to be as easy to use with REBOOT scripts and other modifications required.