Building Mutable Instruments Braids / Learning Hot Air Soldering

I need to learn SMD soldering so I picked up a PCB and parts for the classic eurorack digital oscillator, mutable instruments' Braids by Emilie Gillet. This version has been superseded in some ways by Plaits but I quite like the look of this one regardless.
I tried out a couple different soldering techniques including classic tack-and-place with the iron and lead-free solder paste with a hot air station. The paste wasn't super easy but maybe leaded paste is better for DIY work. Along the way I fried a couple components and had to troubleshoot so I tried to give some insight into how I track that stuff down and fix it.
The module sounds great! I needed to upgrade my case power supply after this build but that's massively improved with a separate digital power rail.
Music used in this video:
South London Hifi - Sunrise Drive - • 🎵 Sunrise Drive - Sout...
Silent Partner - Blue Break - • Blue Break - Silent Pa...
Birocratic - Memory Card Full - • Video
Mylar Melodies - Musik Von Melodies - • Musik Von Melodies | M...

[@richarddorfner698]

I ADORED the ghetto cardboard faceplate!!! Thanks for the video!

[@Feldspar__]

Nice Hammond breaks at the beginning. PCB holder looks like a great tool.

[@vaxdatex8540]

It's a common mistake to use the small air tip under the assumption that you're dealing with small parts. It's very easy to tombstone parts or blow them off with that tip. Using the larger one has easier to manage airflow. The other is to place components like through hole one by one and soldering in stages. Just put solder paste on ALL pads, place ALL parts and let the re-flow station or oven do its magic. Learn to trust the solder mask :). Once you went SMT you never want to muck about with THT :). Ovens are now cheaply available in the $150 range which makes it even more compelling. Biggest challenge is of course parts placement once you go smaller than 0605. At least with my older eyes. Cheers.

[@extralifedisco]

Yeah the reflow oven option sounds nice! I think the all-at-once option makes sense if you have the paste stencil for sure, and on proven designs. I went with 0603 on my designs b/c it seems like the standard size these days, would prefer larger but parts is parts. Not like I'm building mobile phones so no need to go microscopic.

[@vaxdatex8540]

@@extralifedisco From what I've read is that the Mutable boards can also take 0805 parts even though the original design calls for 0603. Plaits and a few others are on my list, so will know for sure once I get to those. For one offs I don't use a stencil so I just put the paste on all the pads and then start placing parts. But made of course the same mistake in the beginning coming from through hole to go with i.e. resistors first, then caps, and flowing them one by one until I realized that it wasn't a) really efficient and b) by doing one sort of parts I would automatically re-flow already soldered parts :). One big learning was to just trust the solder mask will do its job and not worry too much about how accurate the paste is. That and when ordering parts, I always order lots more because there is no way I'm going to search for a dropped resistor on the floor :)

[@dcurry7287]

The resistor joke at 7:42 had me aspirate some coffee. The humor is so niche but everyone who's tried soldering had been there at some point 😁

[@DubstepJeroen]

Little tip: Put the soldering paste on a piece of paper and use i.e a little toothpick to place the paste. makes for a more precise distribution to prevent over applying :D

[@nicholasrichardson102]

seeing this video, I think I'm going to make an adaptor to hook up my programmer

[@darthmarius_vinyl]

so awesome

[@hndmrsh]

Thanks to this video, I was finally able to get my Rings flashed! Seeing a successful flash using the generic ST-Link and the ST-Link Utility was a great reference. In case it helps anyone else, the pin mapping from the generic ST-Link to a Mutable module is 3.3V -> 3V3, GND -> GND, SWCLK -> JTCK, SWDIO -> JTMS (you'll have to check the schematic to work out which JTAG pins are which).

[@extralifedisco]

Ah nice! I think I saw your post on MW. Hard to say what the further issue is but with partial faults I usually start by buzzing out continuity between all the components from input/output to MCU. Along the way you may notice a bad joint, a short circuit, or a wrong component value. It's easier to do from PCB layouts in eagle but I don't have it installed so I just use the PDF schematics on Ben Reeve's website. Good luck!

[@hndmrsh]

@@extralifedisco ah, great advice, thanks! Next step: buy a DMM with a continuity tester 😅. And yeah, debugging this and another module using the EAGLE files has been super useful, and a great learning process.

[@robertsyrett1992]

Nice background music, glad to see you put some mylar melodies in there :)

[@bensthingsthoughts]

Kapton tape is actually Polyimide... that was a great video ! Thanks a lot !

[@AndyTanguay]

This is inspiring. I’ve got some boards around, but I’ve been hesitant to try SMDs.

[@alabamacajun7791]

I would have thought Mutable and the other great module designers would consider power factor correction. Meaning have 1.5& of the energy stored near the regulator to run that module for a few milliseconds. Caps are the best choice before and after regulation. I do also like the well bonded dual or multi -power rail systems. Enjoying your down to earth videos.

[@martingerken7094]

Thanks for all your insights. I'd rather have it manyfactured from jlcpcb ect..

[@electrichartstrings6706]

Quite the coincidence, I just finish my Braids a week ago. Another tip that saves me from troubleshooting after power-up is to print the schematics and layout (at least of the Mutable kits) and do a shorts/opens check for every pin, especially on the micro. I had 3 bridges as I recall that I fixed by checking this way and the module powered up and worked perfectly first time. I also used paste/hot air for all the SMT, works well for me, but I am strongly considering an oven.

[@SoundBecameColor]

Hi I’m building braids too. Do you have a link that explains how to do the checks you mentioned? I’m learning a whole lot and need to find stuff that isn’t working. Been looking for videos on how to check a board but found mostly old guys fixing laptops. Thanks.

[@electrichartstrings6706]

Timothy Renato Pizza No links I know of, although I know there’s lots of videos, etc on general electronics DIY. For the check I was referring to, you need a multimeter that has what’s called a “continuity check” (nearly all of them can do this. To look for opens (solder joints that didn’t quite connect) I use the schematic as a reference and touch one of the meter probes to a pin and the other somewhere else on the copper trace it should be connected to. If the buzzer in the meter sounds, then they’re connected. I do the same for adjacent pins on IC’s, only now I’m check to make sure they’re not shorted (soldered together). If the buzzer sounds in this case, and the pins aren’t supposed to be connected, then I need to clear the solder from between the pins, usually with braided solder wick. Hope this helps.

[@SoundBecameColor]

@@electrichartstrings6706 This helps a lot. THANK YOU

[@AcToneMusic]

That was a great video ! Thanks much, SMD soldering feels a bit intimidating and looks like everyone have a different technique, but thanks to your video and other, it feels more possible. I would not have imagined learning even 10% of what i've learned since i've began diving in eurorack, thanks to people like you that give much of their time and passion to the community :) Long live open hardware, software and knowledge and passionated people ! One question though, I see you are using the solder iron to solder IC's, I'm wondering why prefering it to the hot air gun ? I was thinking of getting one to try myself, do you think it's making the whole thing easier ?

[@Alejandro-kz2zf]

Hello! do you remember the pin correspondence between the micro jtag connector and the pins in the USB device? im trying at it right now and im a bit confused, thank you!

[@Bestmann3n]

how do you like that "hoof" tip? I've got the same one but I don't like it for through hole and swapping tips is a bit tedious. I think the chisel tip actually works just as well for drag soldering so I just keep that one on all the time.

[@extralifedisco]

I quite like the hoof tip. It's no good for tht, as you say, but I think it's more ergonomic for drag soldering with a steeper angle than the chisel tip.

[@odinmp5]

that was impressive, any advice to someone who has built guitar pedals from kits using traditional soldering? i know it will take me months but is there a path you suggest?

[@extralifedisco]

It's not as hard as it looks! Check out some SMT soldering videos by Dave Jones aka EEVBlog for a step-by-step. Also Androkavo's videos on how solder flux works were super helpful to me. I'd suggest starting with something a little smaller than Braids as debugging is harder with big boards. Check on tindie or sparkfun/adafruit for a kit that looks interesting and pick up a binder of 0603 smt parts while you're at it. Good luck! kzbin.info/www/bejne/qpesqHurfN-Ie80

[@xdecidex]

I have this same board, I am trying to figure out how to program it, my pinout is good but I dont know what file to upload to the microcontroller, where did you find it?

[@SoundBecameColor]

Hey great video. I e been trying to this all week with braids. I’m getting pretty good at soldering but still can’t get it to flash. You tested the parts. Can you recommend a video showing how to do that? I’be finished a few kits but don’t have much multimeter experience. I’d love to complete this build. Also, how do you know if it’s ok to power the module with those IC parts missing? I have a million questions. Sorry. Thanks for the great video.

[@extralifedisco]

Interesting! Hard to know precisely where to start without looking more closely. There's a thread on the muffwiggler synth diy forum called "DIY Unsuccessful Mutable builds" where people discuss this exact issue pretty often, I'd post photos and ask there for help if you haven't yet. All I really did as far as part testing in the video was unplug the board and measure some resistor values. Then with the board plugged into power you can test voltages on the IC pins labeled VCC and GND (should be +5v (or 3.3v?) and 0v. Generally it's not dangerous to power a board that's missing components, though obviously that part of the circuit won't function, it won't damage anything. In this case I'd looked at the schematic and determined that the shift registers ICs are used to drive the display, the op-amp and DAC are used for the audio output, so I could remove them and the CPU IC would still work just fine.

[@SoundBecameColor]

@@extralifedisco Cool! I took a break and decided to build Ripples. No bootloading, analog. I ordered 10 PCBs from JLCPCB and got a stencil made so I can cook em with a hot plate. After that I'm gonna go back to Braids. It's a lot to take in. I'm teaching myself everything so... Thanks for the reply.

[@racalik]

Hi! I built my Braids some time ago, but I have a 'small' issue with it - v/oct tracking seems to be a bit too slow. It sort of behaves like glide function was on, which makes it pretty unusable for sequenced arpeggios etc - there's some nasty pitch envelope/glide every time the note changes. Is it something that every Braids has? It's weird. Some answer would be greatly appreciated!

[@extralifedisco]

Interesting - this would be a good question to post on the modwiggler forum for mutable modules. (modwiggler.com/forum/viewtopic.php?f=17&t=143366&start=4025). I would check that the "drift" setting (DRFT in options after clicking in the encoder) is turned OFF as this will create tuning instability, though I don't recall if it caused portamento type effects. Besides that it sounds like you might have a wrong resistor or capacitor value or possibly a short to ground somewhere in the Pitch CV input buffer circuit, near R41 or C16, which could cause slew rate issues on the ADC. However this is really beyond my expertise. The schematic is available here - go in with multimeter and check the nearby component values if you're at a loss (mutable-instruments.net/modules/braids/downloads/braids_v50.pdf). Also - silly question but do double check that you're getting this same issue ONLY with braids and not another VCO, as from your description it could also be a sequencer/quantizer issue.

[@racalik]

@@extralifedisco Hi! thanks a lot for the answer! I wrote to the forum now, let's see. I did check all of the settings one by one but nothing helps. And yes, I checked it against the Neutron synth - I have to set v/oct slew to 10% there to get the sound that Braids gets by default... I will see what they answer, maybe I will have to learn how to use the multimeter.... :)

[@jenniferw8963]

I was thinking about using a hot plate. I can get a 200mm x 200mm one off amazong for around $90. What do you think of hot plates vs air guns? I guess air guns are needed if pcb has smd on both sides.

[@extralifedisco]

I haven't used a hot plate for soldering before so I can't really speak on it. I would be reluctant to rely on it as my only tool as there are frequently defects when soldering entire boards (misalignment, tombstoning, etc) and it would be a real drag to have to re-flow an entire PCB just to fix one part. The choice really seems to be between a hot plate or a reflow oven (I have neither) plus hot air for rework when needed.

[@matthiasuzelac8360]

Hi, I love your videos! They are very inspiring to try more difficult DIY kits. Can you tell me where I can find the PCBs for projects like this? I'm from Belgium (Europe), but I can't find these PCBs at all online…

[@extralifedisco]

Thanks very kindly! All of these DIY Mutable modules are "unofficial" projects, as Mutable Instruments' products are open-source, but they don't sell bare PCBs. I picked up some PCBs from modularaddict.com, which is here in the US. Over in the UK, amazingsynth.com has a great list of many "mutable" PCBs and very detailed BOM lists which I used to help source the components (www.amazingsynth.com/pcb-info/). And over in Germany, Exploding Shed is a fantastic DIY synth shop with a number of "mutated" PCBs and panels in stock for very good prices: www.exploding-shed.com/shop-catalogue/pcbs/ Best of luck with the builds! I'm sure you will get the hang of SMD in no time.

[@matthiasuzelac8360]

@@extralifedisco Thank you very much for your quick response! Looking forward to your future videos!

[@dingalarm]

Excellent build tutorial. How much did it cost to build this module ?

[@extralifedisco]

Hmm, I'm not really sure! I'd guess probably in the range of about $50-$60 USD. Can probably be done cheaper as it's mostly jellybean digital parts but if you're buying SMT resistors it makes sense to get a big resistor kit rather than 50 odd individual 0603 parts that are super-easy to misplace and lose.

[@dingalarm]

​@@extralifediscoThanks! I have a number of Mutable Instruments projects in mind, and similar to what you've said, it would probably be even cheaper if I buy the parts in large quantities (low cost per project). At this stage, I might get a USB microscope, but am not sure whether to invest in a cheap hot air soldering station.

[@SZINNAPALM]

Hey how much did the whole build cost including the flux pen and parts and board, you did a kick ass job I feel intimidated to attemt an smd build. Thats funny you just mentioned Look mum no computer is my girls cousin

[@extralifedisco]

Good question! I didn't keep too precise track of costs but I think the pcbs cost about $35, the flux pen maybe $12, and the other parts about $50. I bought a little binder book assortment of 0603 smt resistors and capacitors off ebay. However finding STM32 chips right now is next to impossible, so that may be an expensive part.

[@JeffreyFournier]

How did you get the bootloader converted to a .hex from .cc?

[@extralifedisco]

I found the .hex somewhere on a forum - didn't feel like installing the whole vagrant toolchain to compile it! Mutable doesn't officially release compiled firmware as they don't want to do DIY tech support but you can find it on other forums.

[@philippedanneel8534]

See my reply to drew above

[@Timossachenverschick]

That STM might not be fried! I had a very similar problem when soldering up my OG clouds including the chip getting quite hot and all, but after some reflowing I got it working fine.

[@extralifedisco]

Yeah, could be! In my experience the overvoltage faults tend to cause permanent failures (probably due to electricity getting through an insulating layer and eroding the silicon). On one ATMega chip I was able to revive it after overheating but one of the analog-to-digital lines was permanently fried. The hoarder in me hates it but I always toss questionable chips because the troubleshooting rule is "it's never a faulty IC* and by the time you've eliminated everything else to discover *this time* it actually is a faulty IC, you've already eaten the cost of a new one several times over...

[@Timossachenverschick]

@@extralifedisco Yupp, thats fair. On my clouds I also just tried getting it running after I shorted the chip because ordering another one would have meant paying a ton of shipping :D

[@IIrandhandleII]

Which brand oscilloscope was that ?

[@extralifedisco]

It's a vintage Hitachi V-355.

[@paraboxmodular]

How do you call the stand that holds your PCB ?

[@extralifedisco]

It's a PCB holder! I think this one is made by Velleman. I also have a little low-profile one called a "stickvise" which I use with SMD components and smaller THT stuff, can't recommend it highly enough.

[@paraboxmodular]

@@extralifedisco thanks, I have found different models on Amazon!

[@charliepopper8570]

How do you upload the firmware?... I saw in another video that I have to target and program again but for the firmware. but the braids firmware file i have it show 3 files when I click the braids firmware folder: braids_bootloader_combo.hex, braids_bootloader_combo.bin and braids.hex.

[@extralifedisco]

Do the boot loader first. You should be able to use either the bin or the hex. Once that works you should be able to load the firmware itself

[@charliepopper8570]

@@extralifedisco So, once the bootloader is upload there is no need to add anything else inside the stm32?... the firmware will load when the braids is connected and ready to use on my rack?

[@extralifedisco]

After the boot loader you should upload braids.hex, which should be larger and take longer to upload. I believe the boot loader is just there so you can do future firmware updates through audio input

[@extralifedisco]

Although maybe "combo" means it has both in one file. Mine were 2 separate files

[@charliepopper8570]

Extralife Thanks a lot for your help and your amazing video, it was very helpful.

[@funkytransport]

hot air for MCU. flux and reflow... they are very robust.

[@machmar]

Hey man, If you need any help with SMD just message me (insta or twitter whatever). I highly recommend you get one of those optical microscopes for both eyes. I have one from china and I can fix phones with it (the parts are 01005 package). Also when soldering the capacitors, combine thw twqo things - put some solder paste on the pads and solder it with a soldering iron.

[@extralifedisco]

The big green magnifier is actually wide enough to use with both eyes, quite handy actually. Probably not enough magnification for 01005, that sounds absolutely microscopic. I had enough trouble with SSOP-8's as it is! Good idea about the paste+iron combination for caps, will try that for sure.

[@casbahrockin]

Nice video! For those on a mac, flashing the STM from source is actually pretty straightforward it turns out if you're comfortable with basics of a unix/linux terminal. I opened an issue on her Github repo with some instructions. If I get a chance soon, I'll probably write up a quick little blog post explaining the steps in more detail for those that are a little less comfortable with the command line. github.com/pichenettes/eurorack/issues/28

[@trukxelf]

This is a great and informative video; but I don't understand why I would learn a skill destined to become obsolete. Robots do this. These components weren't designed for human solderers.

[@oscillosaurus]

It can be a really fun challenge :) I enjoy SMD builds more than TH builds these days.

[@extralifedisco]

LOL, fair enough! For me it's mostly for prototyping. If you're building 100 boards obviously hire a robot but if you're designing a new layout and need a batch of 3 or 4, it may not always make sense to got them assembled elsewhere. JLC's cheap and their parts library is great but it doesn't have absolutely everything - DACs and VCAs and codecs, etc are a bit too niche. Or you may just need to fix a one-off issue from the fab. It's a fun challenge but I wouldn't want to do assembly for a living.

[@leftmono1016]

trukxelf - DIY is quite a bit cheaper. Painting my dining room is way cheaper if I do it myself as opposed to hiring a painter/decorator. And I've earned lots of brownie points for when I want to buy a Super Sixteen sequencer (true story Mr Extralife!)

[@trukxelf]

@@leftmono1016 yes, I agree-in some instances; but it depends on your wage for your work. If a painter works 2.5 times faster than me, then it's best for me to earn my wage doing what I do best, and pay painter their wage to paint. Unless of course you want to acquire painting skills for future projects-but I addressed this in my initial comment.

[@leftmono1016]

trukxelf - but I'm doing my painting at the weekend so I'm still earning my usual wage 😉 Having recently soldered the SMD chip in the Super Sixteen I highly recommend it, very satisfying process. Looks impossible, actually quite simple. Technique learned, happy days.