DIY Lich troubleshooting SOS

Hey everyone.

I am done building my DIY lich but have a problem I can’t debug.

I went through the smoke test and passed. But when I finally mounted the owl board there was nothing. No lights no sound. Just a quick dim flash from my 7 segment screen. (The screen is right side up by the way).

When I remove the owl board and plug the module in, the red LED near the jacks lights up. I feel like something is not allowing the power to get to the owl board. Like when the owl board circuit is locked in, the circuit gets weird and dies out somewhere.

There is this 5v being passed around all over the place and it doesn’t make it to the power header pin just above C11. Maybe its not supposed to be there? Its just that is says 5v there on the board. I am wondering if my potentiometers are touching some solder joints since they are mounted on the opposite of component side. When I peer under there though I don’t find anything :(.

My questions are:

  1. Is there a more readable schematic somewhere that would allow me to visualise the physical relationship between the actual board and schematic other than: https://befaco.org/docs/Lich/Lich_V1_sch.pdf

  2. How do you suggest I debug this? I’m used to debugging software and usually try to follow the stack trace from a function call to the point of failure. What is the electronics equivalent of that? Probably just reading the schematic and trying to make sure that various voltage readings are correct along the path?

  3. My board does not respond when plugging directly into a computer. This is ok right? The owl board requires power through the pins it seems from other posts here.

  4. If the owl requires power through the pins where does it enter the board? Is that even the right question?? Which pins should I test for what values when the module is powered?

Another issue I’m struggling to rule out is a continuity reading between Q1 and R29 and Q2 and R26. But then it seems that they’re supposed to be continuous because in the schematic they seem to be connected in a circuit. I believe I fixed the solder bridge here but I can’ tell.

I’m struggling a lot with this module. It was definitely a poor choice for a beginner but I am so so ok with struggle if I can get it working. This open Owl platform thing is like a dream come true and I am really really excited to start writing patches for Owl. I just wish I could get passed this hurdle!

Thanks,

-Zack

Hi Zack,

First thing: don’t panic! And don’t worry. Build problems are very common, and can always be fixed one way or another.

You’re on the right path, checking power supplies is the first thing to do. I can’t see a power header near C11 though?
With the device turned on, check the voltages at the back of the OWL digital board: GND to 5V, and GND to 3V3. Are you getting +5v and +3.3v there?
Check the 5V regulator, U1. Are you seeing +12v and +5v at the input and output (left/right) pins?

Thanks for replying! :pray:

On the owl board on each pin for 5v volts I’m getting 1.75v and each 3.3v Is 2.3v :thinking:

My U1 seems to be ok. From the back of the board, the rightmost pin is 12v and leftmost 5v. So if it were flipped it would be left 12v and right 5v. The label with brandname is facing inside.

I can’t see a power header near C11 though?

Ah yes that’s definitely not a power header.

Thanks again for your time and brainpower!

Okay, so power is not getting from the regulator to the digital board. That narrows it down!

Is it getting to the main board? Check that the polyfuse, F100, has 5V on both sides.
If yes, then go over the digital board connections, in particular check the solder joints of the male and female headers at the bottom 5V and GND pins, above JP101.
If no, then your problem is at JP2 / JP101.

I wish I could hug you! I see under the pots over the female pin headers… I never soldered them on! :sweat_smile:

I’m not sure if this is the end of my debugging journey but this brings me much closer and I am so dang grateful.

I’m blown away by this community and your willingness to encourage and help. Owl for life dood :owl:

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Just an afterthought: This is my 3rd module build and this + the one before it both ended up with very demanding debugs that were difficult/frustrating during the process and pretty time consuming.

But in the end I like to think that these mistakes are gifts :laughing: … maybe “Happy accidents”

If I hadn’t forgotten to solder that pin header I wouldn’t have found this community when I did, I wouldn’t have learned how to do a continuity test with a multi meter and I wouldn’t have begun learning to read schematics.

Build problems are very common, and can always be fixed one way or another.

Yeah that turned out to be true