Shruthi-1 in "rapid cycling" mode

I have had my shruthi (with moog filter) now working for several weeks, now suddenly it goes into “rapid cycling” mode when i switch it on, so its going by itself thru all the menus.

I tried to turn encoder wheel and the 4 pots in various positions, it still goes on. Is there any way to easily factory reset the shruthi? I could not read about it.

When i short circuit one outer and the inner leg of the encoder it stops. Afterall its an alps encoder, it should not break? Or possibly its part of the electronic circuitry that converts the impulses?

The next thing will be desoldering and tuner spray… Any help or advice would be welcome. This error is really a pity and reduces my trust into this great little box somewhat, if this happened on stage i would have a problem there.

It sounds like you should reflow solder over the encoder pins. if the “click” pin is floating, you will get the menu to change the operating mode: standard, XT, Frank’s XT, on start up as the MCU thinks you are clicking the encoder. Another option is to replace the encoder if the re soldering doesn’t work.

If this does not solve the issue, some pictures of the two boards would be nice. :slight_smile:

Which firmware version does it run?

Is it the XT?

Are you sure it’s not because you have configured it to use a programmer?

from what i can see it changes oscillator and envelope and other menus, as if i would turn the encoder continuously very fast. I am in slovak power grid with no proper grounding, all kinds of funky things happen here… As it looks like, only the encoder or the connection to the atmega can fail, the soldering is ok, i looked at it from all angles and sides (have some experience).

I noticed it stops if i touch the GND pin on the circuit board, probably something in the circuit is catching something “in the air”. i will try to improve shielding in the case and grounding connections…

If you can, measure the power rails with a scope. It they are steady (low ripple) and the right voltage you can be pretty sure its not a power supply issue. No proper grounding in the power grid should not be a problem as long as you use a proper external power supply IMHO.

Try measuring the resistance between the atmega pins and the encoder pins directly. Sometimes the sockets have a bad connection.

I’m trying to think if you could have some sort of ground loop… But I don’t see why that should be the case. Can you try another power supply to see if it changes anything?

As Pinchenettes asked, what firmware are you running? This is important… If one of the later firmwares, and it’s in the wrong programmer mode, it will do pretty much exactly what you described.

i didnt change anything about the firmware, i built this about half a year ago and ordered the preprogrammed chip… is there a keycombination to display version / how to change programmer mode? i already tried two psu’s, one with transformer and 300mA , other one was a switching power supply with 2 ampere. i will try to expose the metal on the case and connect everything alltogether, or possibly some pullup resistor on the atmel inputs? i can confirm the encoder and traces from encoder until the atmel pins are 100% ok, nothing broken, nothing loose.

Ok, since you don’t know the firmware version, what happens when you power on the Shruthi with the encoder pressed?

> is there a keycombination to display version

Normally you see it when the synth boots.

heh, it changes the mode… obviously it was in the wrong mode, now it works again (4 knob). what an annoying usage mistake (for a non manual reader). many many thanks for the fast help guys!

That is what I figured. :slight_smile:
Be careful not to hold the encoder or any buttons while you turn the Shruthi on.