The new Zynthian case is wonderful but the project is slightly disadvantaged by the poor power input method for the Raspberry Pi. In my view, micro USB connectors are not reliable enough for long-term use and are prone to slipping out. I know that many music hardware manufacturers are now using this connection type to save space, but if it can be avoided or improved upon, then this should be a goal. I have 4 possible suggestions for discussion:-
add a cable clamp next to the power input connector to hold the USB cable in place
Semi-permanently attach a USB cable to the case with a blob of silicon rubber
Move the Pi + HiFiBerry away from the back wall of the case and add a more robust barrel connector to the case with an internal USB cable connecting from the PI to the barrel connector
Options 1 and 2 are quick and dirty solutions. People that really need to improve the power input right now can implement one of this 2 methods quite easily.
Option 3 has more “contras” than “pros”, IMHO.
Option 4 is the more elegant, and could have some interresting side benefits, like:
add a poweron/poweroff mechanism
include a small LIPO battery and a charging circuit
I’m not sure what the best solution is, but I agree that the micro USB connector is a poor choice for powering Zynthian. I’ve managed to break off the micro USB from a couple of RPi boards in the past & it’s impossible to solder them back on again.
A dream solution would be to have a USB B ("Printer connector) on the back of Zynthian. Then we can use a thicker USB A-B cable connect to a 5V PSU. These cables have much bigger cores so the voltage drops are much less than with the spindly micro USB cables.
I had lots of problems during booting until I used a better USB charger (2.4 A rated) and a real USB charger cable (2 A rated).
my disco-Zynthian ahs a 5A power supply - but currently with a micro-SD adapter. Will fix this as soon as I have time (and have a free Raspi3 for exchanhing the current Raspi2).
I used the same cable, cut it, shortened it and added a switch…
And by the way, RPi3, Hifiberry DAC+, midi keyboard, ttl midi out, extra leds, touchscreen etc… and never more than 0.6A current draw, even under heavy load.
I would recommend not using any type of USB connector to power the device if you want to move it around, e.g. take to gigs. Even the USB Type B is prone to failure. It is easily dislodged and I have a QX49 that has a faulty socket. (The central plastic locator can become unconnected and push back within the socket.) I would recommend using a standard (as if there is such a thing!) power connector proven in use over many years, e.g. concentric connectors used by Roland et al. (Better still - a locking connector.) Then have an internal power regulator (which could integrate with a rechargeable battery like jofemondo suggested which provides portability plus UPS). (I don’t personally like these connectors but they are still working on my 40 year old musical devices!!!) Or go a stage further and add an internal power supplier with IEC 60320 power inlet to get rid of the wall-wart all together. The further we get away from the micro USB the better (but probably also more complex and expensive).
Regarding power switch - adding a simple, press to make switch between pins 5 & 6 allows a powered but shutdown RPi to be booted. I have this on my Zynth and it works well. Because you don’t generally press it during normal operation it does not interfere with the I2C clock. (I2C recovers fine if you do press the button - it just won’t work whilst the button is pressed.) I haven’t bothered with implementing power off for this button because we have the option to long press the Select knob. I would recommend adding this power-on button to the core design.
Hi. I’ve been struggling to figure a way to make my official V2 kit power more reliable, so I avert rehearsals and gigs trouble, and just found your post. I’d like to mod my kit, so can you please share further details about it? Thanks in advance!
Hey, I was describing an internal solution. The official kits don’t have space for it. I would consider a new USB Power Supply wo the enough Ampere. What are your issues? Reboots? Maybe it’s heat?
Yes, I got it is internal, but i hoped that you had been successful fitting it inside, and was looking for details!
My problem is the micro-usb connector reliability. I had a couple of bad episodes, gladly without frying my rPi3 or the SDcard…
Meanwhile I have read other old posts and i’m considering to glue a good usb cable in place. Adding a 1F 5.5V supercap, as suggested by @Axeman, seems also wise, but I’m not sure where to place it.
And yes, I know these issues have been fixed in the V5 kit, but the small V2 is just perfect and enough for my gig needs, along with the small Keystation 61.
Thx for your hints!
You are really looking at powering via the edge connector as an alternative internal approach. I have gone onto psu pads on the Pi board with plumbing like soldering. At least if an internal connection is made ia the USB c it’s protected from the outside world but you are then exposed to the dubious world of cutting up USB C cable and that is an art of it’s won, and a disturbing insight into quite what cable is actually delivering pwoer to your device.
Thx ofr jumping in with your hints.
I’m trying to avoid powering via the edge connector, so that I don’t lose the protection of the resettable fuse and transient suppressor.
Of course, I would consider that route if I had very good 5V such as the Meanwell, but if I have to keep it external, then I prefer to just fix the connector reliability problem, which is an issue even with the good quality official power supply.
The other interesting topic I’ve read about is the UPS addons, but it seems a bit too much for my purpose…
