No sound and no light in LED 7


I got a Shruthi some years ago, but i am just building it now. I it has been discontinued, but hoping there is still help to find. I am almost finished with my shruthi, or I thought I was, doing the first test, there is no light in LED 7 when starting up (all the other LED works fine, the potentiometers seems to work fine too). But I have NO sound.

So what can be wrong? The missing light, maybe I messed up with the + and -, but does this influence the missing sound?

I haven´t tested it with a MIDI keybord, I will do this later today.

Thanks for making great instruments

The LED shouldn’t influence the sound generation at all. You can check if you accidentally reversed the LED just by looking at it and comparing it to the other LEDs on the board. Looking from the top: at the bottom of the LED is usually a little ring with a flat side. That should be oriented the same way as the other LEDs. If not, you can also check the metal parts inside the LED: One is bigger than the other.

How did you test the sound without a keyboard? Chances are, you simply didn’t trigger a note.

Thanks for the answer.

The LED seems to be installed the correct way, got a new one, so I will try and install that.

And yes, I didn´t trigger a note. Pushed the encoder and the Shruthi played. Pushed a lot of buttons and got something started that sounded amazing and I could control the sound with the pots - so far so good :slight_smile:

Then I connected a midikeyboard, but that didn´t work, no sound / no reaction. So I will look into that. Any idear where to start?

So grateful

Start with the midi settings on the midi keyboard and the shruthi. Check if they send/receive on the same channels.

Regarding the LED: Before you swap the LED out for a new one, check the resistor that is in series with the LED. It might have a bad solder joint on it, or maybe it ist simply the wrong value?

Great I will try that :slight_smile:

Well my friend took a look at my Shruthi (she has better eyes than me) and could see that the LED is connected the wrong way, so I guess that must be why, there is no light :slightly_smiling_face:

Regarding the MIDI. My keyboard is sending on channel 1, and I think the Shruthi is recieving on channel 1 by default (The LCD is not soldered on yet), but still no sound

The 6n137 is in the right correction and the resistors has the right value, so where to go?

All the best

Before you inspect the MIDI section, I’d first try to be sure you didn’t by accident switch it to another channel when you played with the buttons and pots. Since there are only 16 midi channels, you could simply try out every possible channel with your MIDI controller.

If tht doesn’t work, I would check the solder connections that will be hidden under the display one last time and then simply solder the LCD in place. It’s much easier to tell what’s going on when you can actually see something.

If you absolutely don't want to solder the LCD on yet, you can click here

You can solder the pinheader to your LCD and stick it into the holes on the motherboard. If you tilt the LCD slightly so that the pins are pressed into the holes on the pcb, you could actually make good enough of a contact to get the lcd to work. Please note that the the LCD is initialised on power-on, so you’d have to make the contact and then power the synth on. If you are carefull you may actually be able to navigate to the menu that sets the midi channel without loosing the LCD connection and having to reboot the whole device for a new LCD initialization.

But to be honest, I’d just solder it in.

Well this is SO embarrassing. It turns out tha the MIDI in/out is swapped in the quick guide that came with my Shruthi, the MIDI is working and has been working all the time.

Shruthi is working and sound so great :slight_smile:

Now its time to install the LCD - YEAH!

Thank you so much for your help and feedback - sorry for being so stupid :upside_down_face:

All the best

Great to hear it’s working now! Stupid mistakes happen, don’t feel embarrassed - enjoy your new synth!