Shruthi control board: Only LEDs 1, 3, 5 and 7 lit


on the control board of my new Shruthi only the LEDs 1, 3, 5 and 7 lit. I build the Shruthi from a kit. The LCD is not soldered.

When I read the forum I found some hints, but nothing worked!
I checked the 10k resistor network and the ICs are in the right place. The IC 165 has no contact to other parts.

What should I try next? Thanks for your help!

>>The LCD is not soldered

I think you will better solder it… Then try again…

Take a look at the troubleshooting section of this page:
DON’T solder the display until the control board reacts correctly to key presses.

Thanks for your help!
I followed all assembling instructions and troubleshooting hints on this page!

Your Shruthi is in Firmware Update Mode (RTFM :wink: ) so it thinks Switch S6 is pressed at startup. Check that the Resistor Network is correctly oriented, that you haven’t swapped the 595 and 165 and that all solder joints round the 165 and ATmega are ok.


Yeah, my mistake… sorry…

The LEDs are also really sensitive to heat. Its very easy to damage them. When you have also checked the above, take a new led and touch the legs onto the pads of the offending part to check you haven’t done some damage. Make sure you have your good LED the correct way round.

This is not a problem with the leds but with the ATMega going into firmware update mode. This is really well documented, both in the faq and here on the forum. One of the most frequent causes is letting the control board touch the metal tabs of the 7805/7905 on the filter board when doing the first tests. It tendst to rather destroy the 74LS165 (and possibly also the 595).

Thanks everyone! It was a bad solder at the ATMega socket.

Hi Again me,

Now i learned something! RTFM Mode! Ok, didn’t know! Thanks for the information and to stepkus for posting this interessting issue! NICE!

Best, john