[resolved] No boot - All LED's are lit


I finished assembly as per the instructions (this is my second Shruthi btw), but during testing before adding the LCD, I tried booting it, but alas, all LED’s just light up, and no response.

I read this thread: http://mutable-instruments.net/forum/comments.php?DiscussionID=319&page=1#Item_15

I checked pin 24 from the 595, and I get 0.52V on that pin.

If I remove the controller board, and do the checks as suggested in step 4 http://mutable-instruments.net/shruthi1/build/smr4, I do not get the correct values anymore. When I first did the test during assembly, all values were correct. I am not sure if this is normal since all the components have been added in the meantime.

Can someone help me please? Thanks in advance!

Which values do you get?

Are you measuring them with the digital board plugged in or not?

There might be a shortcut somewhere causing a drop of the main supply voltage - low enough to prevent the MCU to boot correctly.

Hello pichenettes,

Thanks for replying!

I removed the digit board in order to make debugging easier.

When I measure on the filter board the GND and the +5V (on the left side where other pins are too, as also written in your build instructions), I get 1,82V, instead of 5V. What else can I check?

Looks like there’s a short somewhere… First, remove all the ICs, because if there is a short, it might damage them.

Use a continuity tester to check the resistance between the +5V and GND point. If you read something below 400 ohm there’s a short somewhere. Now you have to look out for solder bridges on the PCB…

I am confused. I removed all ICs like you said, and out of curiousity I figured why not see how much V i get now, and what ya know, I get 4.97V again. So I started putting one IC after the other back in. I was sure that one of the 6 would be the problem, but even after putting back the last one, the V was still 4.97. So I connected the controller board, and it boots? I have no idea why, but I m not complaining :wink:

Thanks for your help! Now to add the display!

Maybe one IC was mounted backwards?