Shruti assembled but Nothing works


I just finished it and when i plug the 2 boards, no led switching on.
The first test on the filter board (-5,+5 v) is a success.
I checked the resistor( been swapping it because i mixed the bags …), the voltage regulators : ok

When i plug the digital board only on the 5v + gnd, all the leds gets on.

Could someone please tell me what are the test that i could do ??

Thx in advance

Check for swapped chips (in particular the 74hc165 and 74hc595 on the control board). Check that the ATMega644 is not inserted backwards.

When i look to the encoders, the 74hc595 is on the left, the other on the right.

When i look to the other side, the notch of the AT Mega644 is on the side of the shruti logo

that’s correct. are the 595 and 165’s notches also showing towards the lcd?

Yes but the lcd is not soldered yet

do i understand you correctly?
the leds and everything works if you only connect both pcbs only with +5V and GND but doesn’t work when you connect the whole thing including the cv part?
and if the digital board isn’t plugged you get proper readings on both +5V and -5v lines?
what filter is it?

I remade some soldering to make sure as i found that some were not so good:
So now when i plug both cards, i have all the leds on…

It’s the smr4mk2 v0.1

Readings checked and ok
How do i check the at 644 ?

you can try if the leds respond to key presses. also, hook it to an amp and keep S1 (the oscillator switch) pressed for at least a second. that switches on the test tone. and, you can hold the LCD in place without soldering it and see what it says. just make sure to make good contact during boot, otherwise there may be random letters and you need to boot again

No led response when i press a key.
Nothing on lcd.
Plug to amp and keep s1 :no test tone, cable check i have a ground noise when i hold it and whne it’s plugged no more noise.

Wtf have i done ?

Good morning all,

Is there a way to check the chips ? Does someone have the same problems, i’ve searched in the forums and nothing found.

thank you

When theres no Response to LEDs it might be the ATMega isn’t booting due to problems with the solder joints around the Oscillator. No Clock, no booting :wink:
Check these and the corresponding Caps.

Sorry for my noob question : what is the oscillators ?

Q1 (the quartz), C6 and C7 (two of the 18p ceramic capacitors). The processor (Atmega) has to do things in a specific tempo. To do this, a signal with a certain frequency has to go into pin 12/13 and the exact frequency of that signal is controlled by those components.

Great i will check this as soon as i go home.

Thx all for your help, i hope i will get to the end without buying a new kit…

Check if you haven’t mixed up the 18pF capacitors with 100nF capacitors, their shape is very similar…

while you’re at it just go over the MCU pins as well and make sure they all have nice looking joints.
i’m sure you won’t have to buy a new one :slight_smile:

Hello Guys ´n girls,

18pf are ok . One pin was touching the plastic bottom of an encoder, i bended it with the solder iron.
I’m not sure how to check the q1…

Here is some photos, if this can help… ( T_T)\(^-^ )