Shruthi malfunction?


I built a Shruthi 2 months ago. It worked great from the start.

The last three weeks it has become less and less reliable (low output/attenuated high frequencies/distorted output), and last night it stopped producing any significant audio at all.

Originally I suspected a dry joint on the output jack, but there appears to be no issue there.

The display & LEDs are still working.

I removed it from its case last night to discover that IC9 is too hot to touch.

Does anyone have any suggestions - I’m already missing this synth :frowning:

Thank you.


you must have a faulty solder joint, IC9 is not supposed to be that hot.
Or maybe your dc adapter is too “strong” and provides too high a voltage.

Check the voltages, make sure the power supply is not higher than 12v, and then check the +5 and the -5v are correct. If they are not then check the power supply section.

Thank you for your suggestions MicMic Man and Dunk.

It turns out I had two issues!

Firstly, my 12v power supply was reading 15v across the v-in of the Shruthi - swapped for a 6v supply and the power regulators are now running cool.

Secondly, on close inspection (with recently acquired reading glasses I discovered that I had failed to solder three of the pins on IC2 on the analogue board - presumably the source of my intermittent signal)!

So my Shruthi is both functioning and finished now!

Once again, big thanks to Mutable for the cool synth, and my apologies for being a bit newbie! (Not used a soldering iron for 15 years… SOS tempted me out of retirement!)


PS Elite on the Beeb had nine months of my teenage life!