Project Organization - DIY Mutable Elements

[Bretd]

I was hoping for advice from experienced builders as far as the ordering of steps to take on projects, using my upcoming project, Elements (Eleanor) as an example. Emilie's schematics for Elements includes 5 sheets:

1. Main processor
2. Audio I/O
3. CV I/O
4. User Interface
5. Power Supply

I was going to attack the build as follows but ran into a few questions, and perhaps I am leaving important steps out:

Step 1: Solder power supply sheet components, verify voltages.
Step 2: Solder Main Processor sheet components, verify connection to the processor

- Is there way to verify that the crystal is properly soldered and works before programming the processor without an oscilliscope?

Step 3: Program the Processor
Step 4: I am unsure if I should just finish soldering the remaining sheets all at once or if there is a way to test as I go?
Step 5: Add a few jacks/pots to test with.
Step 6: Finish adding hardware and test further.


Any help is greatly appreciated.

Thanks

[soejrd]

What was it about?

[sduck]

Yes, it seems odd to dump a post after only a few hours or whatever. Maybe that 35th view would have triggered something. What was this about?

[Bretd]

Apologies, it was a rough day yesterday... got frustrated at other things going on. Post is back up.

[bgreeves]

Apologies, it was a rough day yesterday... got frustrated at other things going on. Post is back up.

It happens, no worries.

Maybe that 35th view would have triggered something.

I know the annoyance of seeing the view count rise on your post with no engagement. Keep in mind that many of the people who click on a thread are just interested in hearing what others have to say on the topic, even if they have nothing to offer themselves.

- Is there way to verify that the crystal is properly soldered and works before programming the processor without an oscilliscope?

None that I know of. You can however get a passable oscilloscope on the cheap. I have the DSO138. I think this is the kit I got:

There are others where you can get the board pre-populated and you could buy a case separately if you wanted.

Not sure if the DSO138's sample rate is high enough to accurately measure the crystal's output, but I'm sure there is another affordable option that's fast enough and isn't some multi-hundred dollar metal box.

Could it be sufficient to just probe the crystal with your multimeter and ensure that it's putting out something?

Step 4: I am unsure if I should just finish soldering the remaining sheets all at once or if there is a way to test as I go?

For something as big as Elements (haven't seen the circuit myself but can't imagine it's small), yeah, I think this would be a good idea. Study the schematic, maybe print it out, and divide it into mostly independent chunks that you can test.

It's great that you're already thinking ahead and planning to check in on the success of your build at multiple points. That approach is sure to save you some major disappointment if anything does goes wrong.

Wishing you the best of luck!!

[Bretd]

Thank you for your reply. Greatly appreciated. It looks like I'll be weighing my options for oscilloscopes in the near future. Will definitely check out that DSO.

I looked more at the schematic per your suggestion, and will probably hit the remaining sheets by first doing the entire audio sheet.. perhaps I'll get some sound out of it at that point.... and then the cv and user interface sheets seem to already be broken up into good chunks that I can test as I go.

https://mutable-instruments.net/modules ... ts_v02.pdf

Thanks again.

Any other tips are greatly appreciated.

[sduck]

How are your soldering skills? Elements is a pretty intense project to take on if you're just getting started with smt (or any kind of) soldering.

I built a few ornament & crimes before attacking my first elements - they were my introduction to smt building. And the first elements didn't work - I soldered the processor in backwards, and didn't want to bother with desoldering it. The second one I built worked, sort of, but apparently I fell victim to a bad pcb run and only half of the knobs worked correctly. The third one i built worked. This was years ago, i've built tons of other stuff since then.

What I do typically with these kind of things is solder the processor and larger smt parts first, then attack the smaller resistors and caps and such. Then just go ahead and finish things up - I don't really do any testing until it's finished. Typically things just work - if they don't, at least in my case it's a flubbed solder somewhere that i can usually find pretty quickly.

[NeolithicElectrophones]

Agree with sduck that Elements is a heavier project and might not be the best to start with. Something like Ripples, then Braids might be better to start out on if your smd skills are limited.

My advice would be that if your'e starting out on Elements, going from the power block, testing that voltages are correct, then moving onto other parts will possibly help save some fried chips and headaches. Also use generous amounts of no-clean flux when soldering and be sure to clean it after.

The order I tend to do projects like this is: power components soldered - power and test- ICs- passives- test continuity on power rails- flash- add panel components.

The above method isn't critical for more spaced builds but of you end up soldering some of the tighter ones with ceradiodes in between jacks or closely spaced DACs then I think it really helps.

[bgreeves]

Also use generous amounts of no-clean flux when soldering and be sure to clean it after.

[Poldenstein]

Hallo,
Usually I follow this procedure (read somewhere here or on Facebook):

-populate power section (last page of schematic) and check for voltages
- populate MCU and flash it (no need to bother with crystal for that)
-populate all other components except for panel ones (jacks, pots, switches) and clean with IPA
- test the unit with panel components in place but not soldered yet (in case troubleshooting is needed. It would be an hassle to desolder them to reach for parts).use the panel to keep everything in place.
-solder panel components and enjoy!!

[Bretd]

Thank you all. My soldering skills are fine, and have completed a good amount of smaller sized builds like ripples, grids, branches, various vco's, Nutella, a few antumbra builds like knit, 6mix to name a few. I will admit that I was a bit lazy with testing at times and did have a few requiring some debugging but nothing terrible. This post was essentially to be sure I wasn't skipping any steps in the process, and just to get others' takes on their way of doing things, as the projects are getting bigger. Greatly appreciated to all that replied.

Definitely not skimping out on the flux...it does magic! The cleaning process is a pain at times. I use alcohol, and it comes out okay but cant stand the cotton coming off the q-tips at times (or even paper towels)... Any tips on alternatives? Thanks

[NeolithicElectrophones]

I use alcohol, and it comes out ok but cant stand the cotton coming off the q-tips at times (or even paper towels)... Any tips on alternatives? Thanks

I use kim-wipes and a toothbrush. Boards come out very clean.

[Bretd]

These?

[NeolithicElectrophones]

Can't see a pic in your reply.

Should have written kimtech in my earlier post. I usually get a twelve pack every year or so. Takes maybe five or six sheets per Medium build.
https://www.fishersci.com/shop/products ... 7/p-211240

[forestcaver]

- Is there way to verify that the crystal is properly soldered and works before programming the processor without an oscilliscope?

None that I know of.

You can check the mcu is working at the correct clock speed by using a programmer (eg stlink)... (before flashing). Even with an oscilloscope (depending on the scope and the gear you have) you may struggle to measure the crystal....
After flashing you can check the mcu is running properly with a debugger (eg openocd/gdb)...

[sduck]

... Any tips on alternatives? Thanks

I use kester 331 water soluble flux solder for most stuff - everything that can be water washed, then do regular washing with just hot water along the way. For final stuff that can't be immersed, I use kester 245 no-clean solder. This produces excellent clean looking boards with minimal muss and fuss.

[fitzgreyve]

I've just built an Elements, a bit of a story and a warning:
This is a PCB with black text on white resist - not sure of who made it originally (EDIT - it looks like it''s magpie modular/elecrow). There is no resist between the pins of the STM32 (common with a lot of cheaper PCB manfufacturers that can't/won't work to the finer tolerances).

Build approach was similar to above:
- install power and reference and check it's working.
- I then installed all other SMT components. I generally work by ease of access - generally this means IC's first, then passives, electrolytic (can) capacitors last.
- STM32 was a tiny bit out of orientation, looked OK, but wouldn't program (using ST-link V2 and hex files).
- removed STM32, replacement installed. I used a lot of hi-rez photos to check there were no shorts between pads both before and after soldering (I'm hand soldering). It programmed fine. Leds flashed at power up.
- installed the "blow" pot - I could now get "firmware update" mode at power up - so clearly working.
- installed all the trimmers. I could now get "calibrate" mode at power up.
- Also got some basic audio output (given no controls installed). Installed about half of the pots - it made controllable audio. Happy Days (actually "fairly ecstatic days!").
- Installed all the sockets - no problems.

However, I then installed the rest of the pots. Guess what - "nothing", no audio, no leds at startup. Dead short across the +3v3A supply rail (IC2 running hot, output about 0.2V) 0.6ohms between the +3v3A supply rail and 0V. It's probably either a duff pot, or poor etch resist around a +3v3 connection. Going to be tricky o debug without removing the last installed pots.

Moral: if you do get it (partially) working, go one step ("one pot") at a time from then on!

[forestcaver]

I’d also suggest - dont solder pots, jacks and switches until you have completely tested absolutely every input, output and every function (I usually do this with a function generator and oscilloscope). These components usually give a good enough contact when just push fitting. If not, helpful pressure from a finger/fingernail helps... much easier to fix errors if these arent soldered when the components are on the top....

[Bretd]

Excellent info. I will follow this advice. Can't wait to start this one over the weekend.
Thank you!

[sduck]

I've just built an Elements, a bit of a story and a warning:
This is a PCB with black text on white resist - not sure of who made it originally (EDIT - it looks like it''s magpie modular/elecrow). There is no resist

That was the one that I built that kind of worked - some sleuthing and it turns out there's some problem with the ground layer, that's almost impossible to fix. Mine made sounds, but most of the knobs didn't do what they were supposed to, and some of the cv level knobs did what the main knobs were supposed to - it was a huge mess.

[Bretd]

If anyone comes across this..... after finishing the power and main processor sheets, I programmed the IC using ST Link Utility program (v2 programmer) and files provided by Pusherman. I believe it was successful bc I followed that up with finishing the audio I/O sheet, connecting i/o jacks (without soldering) and got an output when connecting external audio. So it seems like so far so good.

Thanks again to all that replied.

[bgreeves]

Congrats!