No sound from XT. Is this the right behaviour when jumpers for digital volume control are in place?

Discontinued products Shruthi
#1

Hi All,

I received a Shruthi XT yesterday, and after completing the soldering last night I’ve finished the build this morning.

All buttons and pots on the control interface work. They all do something.

MIDI is clearly OK. I’m sending MIDI data from Cubase and seeing the little note icon on the Shruthi’s screen.

But I can’t hear anything at all.

I jumpered the connectors near the volume control so it would work as a digital volume control, on the basis that I’d always have it at max and control the gain downstream anyway. But when I turn the volume pot, nothing happens. Is this normal? Or should I see some indication on the screen that I’m changing volume, just like every other parameter?

I’ve also probed where the OSC signal should travel between the control board and the filter board, and I’m getting nothing there either.

So I guess the first thing to check off - when I twist the volume knob (when jumpered for digital control) should I see the screen update? Cos I don’t at the moment…

Thanks

#2

No, the screen shouldn’t update when you turn the digital volume knob.

Irrespectively of the status of the volume knob, you should get a signal on the OSC pin, so there’s clearly something here. Maybe a bad soldering joint on the microcontroller? Or a short between two adjacent pins (MCU or header?)

#3

Thanks for the reply!

I’ve been through with the multimeter on the header and the microcontroller and soldering looks OK, and there are no shorts. What’s the MCU?

Also, looking at the schematic it seems that pin 18 of the microcontroller is OSC out. I suppose I can just probe there to see what’s coming out can’t I?

#4

One thing - I do get a very short beep when checking continuity between pins 9 & 10, and also 30 & 31.

#5

Seems that reseating the mictrocontroller did the trick. Strange.

But no big deal - it’s up and running now!

Thanks for this great project pichenettes!