No sound out of anushri :'(

Hello everyone,

yesterday i finally got my anushri assembled.
I think i soldered it cautiously, but then, when testing time arrived, absolutely no sound came out of the synth. Except a few noises when moving some pots.
anyone experienced this?
just asking for some hints before going deep in troubleshooting.


Hi ozu. What kind of noises and which pots? Is your PSU adequate; how is it rated? Try factory resetting the synth first by holding Run/Stop whilst powering it on. Once it has been on for a couple of minutes, auto-tune the VCO by holding ‘Hold’ and pressing ‘Run/Stop’ once.

Is it receiving midi? Does the gate led flash when you press a key on the midi-keyboard?

nope, i don’t think it receives midi. no flashing led…

Did the voltage tests check out? Take all the chips out (except the LT1054) and check the voltage regulators first.

ok, thanks for the tip. i will when back home!

but yea, i didn’t know if i should expect flashing leds when sending midi, so now i know it may come from there.
anything special i should check midiwise?

thanks a lot for help!

check the orientation of the 8-pin chip next to the midi-connectors: 6N137

Check the orientation of the optocoupler IC 6N137 next to the MIDI sockets. Are any of the LEDs lit or flashing when you power it on?

Even without midi you should be able to have it play some notes by holding the bottom right button.
You should probably read both the manual and the building (troubleshooting) section more carefully.

@ gphg + toadstool : i will check 6N137 (but as far as i remember, i checked them all and they were properly orientated)
@ toadstool : yes, 2 leds are flashing when powering it on ( up + up left), the up one is changing slowly.
@ MicMicMan : i did hold the bottom right button yesterday and nothing happened + i promise i will RTFM today.
and probably get back to anushri on sunday evening!

thank you all for helping!

OK, are they definitely both flashing? The top LED of the left-hand vertical line should be permanently lit, the left-hand LED of the top horizontal row should be flashing. If that is so then it sounds like it has booted properly because the synth page LED is lit and the LFO LED is flashing slowly…

Hello again!

so, i made a few tests… but still haven’t removed all the ICs + checked voltage.

first of all, i resetted to factory settings. Then I held the bottom right button (drone mode) as suggest by Micmicman. All I get is one click sound.
Then i pushed the middle right button (run/stop), then I get sequenced clicks (+ gate led flashes) but still no proper oscillator sound.

I checked 6N137 orientation, and it looks ok, but I have no Gate LED flashing when input from the midi keyboard. But when I feed the modular analog gate input (from my nanozwerg lfo out), the gate led flashes + I get sequenced clicks again (tempo is related to nanozwerg lfo speed).
So my guess is that there are 2 problems : midi is not received (though 6N137 is properly orientated) + no oscillator sound.

If i turn both lfo mod + resonance to max, i have a very weak sound (like auto oscillation responding to the lfo). So my guess is that the filer should work.

any ideas? should i buy another 6N137? but even if it would cure the midi in i’m not sure i would cure the oscillator…?

thanks a lot for helping!

You should definitely check all the voltages first using the ‘Troubleshooting’ section of the Anushri build pages

Which voltage do you have on pin 6 of the 6N137 when MIDI data is transiting?

so i just checked pin 6 of 6N137.
Voltage is -0.02V when midi is transiting and also when not transiting…

Pin 8 is 4.96V

… and i just checked all voltages as shown in the power distribution picture in the Troubleshooting section, but WITH all ICs inserted, and everything looks just FINE.
Should I check with ICs removed (I admit i’d like not to remove them…)

I guess it is quite impossible for me to check both Signal Path + MCU as I don’t have any oscilloscope.

Thanks for helping!

Check if there is a short between pin 6 of the 6N137 and the adjacent pin - or if the 10k pull-up resistor is correctly soldered.

By 10k pull-up do you mean R2?

Yes, this is R2