Blank screen (HDMI Shows boot to black screen with terminal prompt))

Hello everyone! I am currently building a very custom Zynth inside an old Gamma Ray Detector. I am using The v2 kit and a pi 3.5 TFT screen as well as a HifiBerrry DAC+ soundcard

I got everything hooked up EXCEPT the 6-pin optp-couplers. I figure since I’m only using USB midi controllers I don’t need to bother with those. Am I very wrong? Could this be my Issue?

I am also getting a low voltage warning whenever I plug everything in. When it’s just the pi and Hifiberry I do not get this warning.

I also wanted to point out that the mcp23017 gets extremely hot when powered on…

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That shouldn’t really happen ( or rather I’ve never noticed one getting warm . . ).

You might well have something slightly array in the Power to the AllinONe board.

Might be an idea to unplug the AllinONe selecting Dummies in the Wiring settings ,
Then plug a mouse in to the USB port and set up cursor on in the webconf. This will allow you to drive the interface from a mouse without encoders to check basic functionality like test sound.

Here are some pictures of the All-in-one board:

And one of the Gamma Ray detector case:

I am still getting a that voltage warning and the screen only backlights. I am using the same 2.1 amp charger and quick charging cable I’ve always used for my pi-projects, but I have never used a screen before. I am about to check with a vanilla raspbian image to see if my pi-screen is working otherwise and will report back.

I think that something about this setup has also bricked my rpi3. Even with a fresh image of raspbian, it will not boot pass the splash screen and the PiTFT also does not work. Interesting side note: the GPIO expander does not heat up at all with this raspbian card. I’m completely at a loss here… damn

Start by disconnecting everything… Do you have an separate HDMI monitor?
You can build a fairly brain dead zynth around just a raspberry pi (by selecting custom and dummies), which will reveal which of the base bits are working .

IF you can get things running with an hdmi monitor/hifberry card & Pi then those bits all work ok…

It’s perfectly OK to omit the optocouplers if you are not using the MIDI ports. No problem at all. In such a case, you should also omit the resistors, capacitors and diodes related with the MIDI circuit.

Your power supply is not good enough, or your USB devices take too much power. Try with a better one …

Ups! Something is wrong in your circuit, my friend. The MCP23017 never should be hot, as it’s a low speed digital IC. If it’s very hot, you have a serious problem. BTW, is it placed in the right position? :wink:


Please, send photos of the top side!! Some component should be misplaced …

Okay, I’m back at it now! Thank you for your time and consideration. I have been looking more closely at the documentation and I found that I have been trying to plug in the 40pin connnector inverted on the all-in-one board… oops. I am a bit of a noob when it comes to actually playing with circuitry.

Here is the top of the All-in-one:

So, without anything connected, I can get my pi3 with the Zynthian card to sort of boot, but it always gets to here:

Then It switches to a black terminal-like screen with a prompt. It’ll even flash between a blank terminal and that last screenshot?!

Also, I am unable to get into webconf… When I attempt to I am greeted with this message: “500: Internal Server Error.”

I just checked a different distro with the RPI3b+ and found it to be working. I also just tested the PiScreen and it appears to be working… Apparently you have to install drivers for the screen… lol This is a learning process for me.

Also, I was able to get to the login prompt through the network! Progress!

I appreciate any time you guys have/will spent/spend helping me with this and promise to represent this project as best I can. But it’s off to work for me for now. See you at 5pm (-6GMT)

Well the behaviour you describe is often mis configured display and audio settings ie you use an audio injector card but it’s configured for hifiberry or you have an hdmi monitor but the zynth is trying to run 3.5 waveshare…
The webconf is where you sort that out but… The 500 means that you have actually asked the webconf a decent question but it’s failed whilst running whatever it was running so that does at least prove something is going on.
Probably the next step is to log onto the zynth using ssh which means loading up Putty on a seperate machine and filling in the address of the zynth. Unfortunately if you are running Windows and most people do then you probably can’t use names (zynthian.local)…so you will have to see if the zynth reports an ip address when it kicks off. Once you have a putty login then it’s time to see what is actually running…
ps - ef | grep python
Should tell you what’s going on and you might well see webconf running…

So of course what we need to do and stop webconf so we can run it in such a fashion that we can look at it’s output when we ask it questions…
To stop it type…
systemctl stop zynthian-webconf

You do it this way because anything else will be restarted by system (the programme systemctl talks to)…
Once you’ve stopped it you need to go to the webconf location and start it by hand…
cd /zynthian/zynthian-webconf
And then run it…
(I’m typing on my phone from memory so I might have a name wrong but the basic idea is pretty simple)

Once you’ve done that and if it stays up. Then try accessing the webconf again… You should get a traceback that will tell us why it’s failing. Cut and paste whatever it says up here and we should be able to fix it and then I will politely request a sound sample cos that’s what I do…:face_with_monocle:


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Are you using the Aruk RC3 image?

Since I am building with the v2 kit I am using:
“Zynthian “Gorgona Omega” SD-image, configured for Kits v2”

I have tested my hardware and confirmed that everything works except for the all-in-one (which may work too, I just haven’t been able to test it). I will try the things that wyleu mentioned this afternoon and report back. Oh and I’m using Linux as my main OS so I was able to use zynthian.config (or whatever it was). I was also delighted to see the RPI3 in my routers connected devices list. That tells me that things are working just not configured.

Actually, one more question: Is it possible to run all this from a travel charger that outputs 2.1Amps and 5v? If not I will look into a more substantial battery

No no, you should be using Aruk RC3 for V2 too.
Gorgona os no longer supported!

Okay, thanks!

I now have Webconf up and running.

So, I got everything except the rotary encoders to work. Is there some setup I am missing here? It’s possible I burned out the mcp23017 and that’s why they do not work.

I’m so close to finishing this awesome thing!!

Have you checked that you configured the correct kit in the webconf?

Opinions vary… :slight_smile:

In any rig I’ve ever tried with a USB battery pack it tends to get low voltage warnings, but it seems to function. I want to specifically run that way for guitar processing (& keyboard MIDI as well :smiley: ). Safe on stage, no mains hum contributions or common earth except via signal lead.

If it will record a forty minute set as well, so much the better.