[solved] No power on motherboard

Hi all !

Just received my pack of 2 shruthis this morning and spent the afternoon to solder everything…Took me some time as I checked twice each step of assembly…

I checked the power of the filter board and all he checkpoints are fine (0, +5V or -5V depending of te measuring point). When I put the filterboard and the motherboard together, I get the +5V on the motherboard…but nothing happens, no lightened led, no heat, no smoke no nothing…I’m so disappointed…I wish I would have heard my shruthi tonight…

Where do I have to start to locate the problem on the MoBo ?

Thanks by advance !



Hi all, thanks for your replies

No LCD installed for the moment…As mentionned in the tuto, I wanted to check everything before soldering it !

I think I found the problem. The power is arriving on the +5 spot of the Mobo, but no +5 at all on the board (tested contacts between GND arrival and atmega pins and several other points).

I’ve had a problem during the soldering of the 8×1 male connector (a bit tired probably, I soldered it on the wrong side of the PCB…DOH )… It has been kind of a hard work to unsolder it and I think I’ve burnt the +5V track inside the PCB…I made a (temporarily) bridge between the MoBo +5V arrival and the positive lead of cap C4…and…IT WORKED leds are on and I can switch between pages (well pushing buttons puts other leds on (except one I think, is that normal ?). This temporarily voltage bridge will unfortunately but surely make this Shruthi really unique and mine

Do you think this “bridge method” will do the job ?

Anyway, working all day, I’ll keep you aware of the results tomorrow !



so you know the 5V are at all spots?

lcd trimmer adjusted? (no joke)
atmega inserted correctly?
connector ok?
bad joints?

Do you at least get the LCD backlight? Even with a dead or missing CPU, you should at least get the backlight. If not, check that you get +5V on one of the leads of the 68R resistor (the one that is the closest to the MIDI connector).

If you get LCD backlight, then it’s likely to be a problem with the MCU.

Final question: you mentioned two kits… do you have the same problem with both?

If you have a v0.7 board, there are two other pads for +5V, you can also make bridges to these points.

You have to press several time on a switch to light the LEDs associated with it (for S1 and S3). Pressing S5 toggles LED7 on and off.

Hi all

Still trying to get my shruthi working…

NO LCD backlight even if I have +5V between gnd and one lead of the 68R resistor…

By the way, I can’t get LED 2 on with all the buttons combinations I tried and moving the encoder…this seems not to be normal I think…

Any ideas ?

Ok now I have the backlight…Checked all the solder joint and redid some of them which were a bit weak…let’s see for led 2 now !

led 2 is Ok now…but no way I can adjust the contrast via R21…

contrast is ok…damn bad solder joints…

nice to read you :slight_smile: yeahhhhh go for soundddddd nowwwww

well…no sound for the moment…seems like I have another problem with midi in…when sending a C4 using my sequencer, I’ve got no sound from audio out…and no drawing on the screen showing midi is arriving

No midi working…I tried with a sequencer and a keyboard…No little sweety note on the screen when sending a C4…sad…

I’m a bit lost now…How could I find where the problem comes from ? Any help would be appreciated



in this thread:

Rumpelfilter is talking about a midi jumper…I can’t see what this means…Did I miss something guys ?

Yeah there is a jumper, i search a photo to show you. For testing sound ability, you just have to push during about 1 or 2 seconds the first shruti’s button form left :wink:

finally i don’t remember if there is one on the Shruthi…On the Shruti there is, but Shruthi??? lol sorry

yeah there is. it’s called test tone and is described in the manual.

Using the switch to generate a C4 is working fine…I get sound…I have to investigate the jumper topic this afternoon

so at least you have a drone synth now :wink:

I’ve got +5 between ground (pin 5) and VCC (pin 8) of the optocoupler 6n137…so I guess it’s not fried…I didn’t find anything in the reference manual about the midi jumper…seems like it was for the shruti or previous rev of the shrutHi…

What else (as would George Clooney say…) ?

Ok…remade the solder of 220 R…it works…I think this show that it’s not hard to build a shruthi…it’s hard to be a good builder…