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How do you trust your builds ?
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author How do you trust your builds ?
leadtinsoldier
Hi everyone,

I recently started DIY by buying everything needed to get a 10 module system - 100% DIY (including PSU, external MIDI to CV, etc). Don't tell me it was a bit ambicious : i figured out myself.

Slowly, things are getting more and more serious : i should be able to run 4 working modules controlled by my digitakt at this point, but i just don't trust my modules.

It may come from a lack of experience with electronics, but i can't stop myself from thinking that even if everything works at first test, there might be some slight default that suddenly shorts all my system and destroy my precious work... Or even just plugging the wrong patch cable at the wrong place, or too violently, and again burning some chip, shorting the all PSU, etc.

So i don't know how to be more explicit about this : how do you trust your builds ?
Noodle Twister
I trust them by examining the solder joints after each stage of the build or handful of components. With more successful builds the trust in your own soldering and the ability to spot bad joints gets better.

Double checking things like IC socket and chip orientation and just about everything else that can be double checked helps too.

Have a separate power supply for testing if possible or just test one module at a time and use a multimeter when you can.

Definitely avoid soldering when tired. Even more important if your de-soldering.

That's my experience so far.

Finished a Zlob modular dual VCO yesterday and after testing it separately it's now in my case It's peanut butter jelly time!
cackland
Don't rush your builds. Take your time and examine everything many times.

Always check your work with multimeter or oscilloscope if you have access to one.

All in all, keep your builds simplified enough till you gain confidence to explore further, building more complex projects. And even if it is a complex build, break it down in to building blocks, test and go from there.
Jaytee
Think of it this way instead: even factory-built stuff will eventually break/wear out/otherwise require servicing. And sometimes it doesn’t even work when brand new!

The cool thing about DIY is that as you progress, you’ll become more competent at fixing issues as they crop up, and you’ll already be familiar with what might be wrong since you built it all yourself!
wackelpeter
as above, testing with a multimeter for shorts on the power rails, before you plug it in... also do rotate the pots for pitch, cv Cont rol or anything else hooked up between +/- or +/gnd and observe the multimeter… Maybe a pot is defect or you have something soldered the wrong way and can then detect the culprit…

Also i inspect before i hook my modules into others the Output of the modules with an oscilloscope… to see if i get all the signals that i would expect and that they're in expected range. The Osci must not be anything Fancy... you'll find cheap and working ones starting with 50-100 bucks at eBay... aside that it's a nice and helpful tool i highly recommend an oscilloscope as i think the Programm there is Always better as the TV-program and i can spend Hours watching some nice folding waveforms… (that's what i usually do, interrupted by a Little bit of wiggling hihi )

Furthermore the advice to be careful when desoldering doesn't only mean to be cautious with the length of your desoldering Task (avoiding to pull off tabs) but when you use a solder sucker, be Aware that there often fall small Digits of solder out of them and These may create a short if you do not carefully clean your board afterwards…

And well cleaning is Always a good advice, first of all remains of flux can introduce all Kinds of Trouble and a Bridge shortening two traces is better to spot without remains of flux covering it...

...finally regarding your PSU, especially if with mains voltage, better let someone inspect it before you plug it in by someone who has experienced Training or is a electrician/electrotechnician or otherwise qualified.

Otherwise there'S not much left to say as echoing and seconding all of the above.

happy soldering w00t

Edit: in my early builds i have included some fuse holders for the rails… while i was suspicious of the shut down and self-protecting capabilities of my PSU... I then started with small fast fuses (150-250F mA) for each rail to see if everything was correct, but then ended up changing them for slow heavily overrated ones (5 or 8T A)finally…

Experts would say that'S nonsense what i did… and well they're Right... first of all the fuse itself adds resistance and the more current you draw the more it's resistance goes up introducing voltage Drops on your rails…
also with the overrated fuses you still have the resistance of the fuse holders, but okay These remain stable… perhaps you can build something similar between your module and your PSU just for testing purposes, so you can easily get rid of it by hooking your module directly to the bus board when you came to the conclusion that it works properly and be on the super safe side when testing it...
toneburst
Don't do the sockets, pots and other hardware after finishing the rest of the build at 2:00am.

I've done that with a few modules, and had wonky jacks and other immediately obvious abnormalities.

It doesn't matter how neatly soldered the boards on the back are, if the parts you can actually see when the module is mounted are messy.

Better to clean the boards, before getting some much-needed sleep, and tackle the final components the following day (or the day after, if you're sleep-deprived).
EATyourGUITAR
no need to worry. everything can be fixed easy. if the power supply fails you can fix it by swapping one part. they never have two parts fail at the same time. if a module fails, you can fix it. this is much better than if it fails and you have to buy a the whole assembled module.
Rob_C
A good strong light and a magnifier are essential for inspection. Being your own critic and inspecting as you build will improve your solder skills. That adds to your confidence.
Joe.
I power the module up on an isolated power strip, I test all the functions repeatedly, and I leave it switched on for a couple of days before it finally joins the rest of my modules in the rack.
pfzzz
One of the failure points I had before was a resistor that was faulty, had a different reading on a multimeter than what was advertised, so It was my first built that was why I was testing everything, but knowing that, I will probably get one of those component testers off ebay, I know it's cheap and not accurate, but that resistor had 30kohms difference so it can be a fast way to test at least do a sanity check resistors which you would have bunch of them
AlanP
leadtinsoldier wrote:
So i don't know how to be more explicit about this : how do you trust your builds ?


I first check continuity between -12V and ground, +12V and ground, and +12V and -12V. (Quincas Moireira (spelling?) turned me onto this.)

If I'm feeling lucky, I'll power the new module up straight off the modular's power rails. This probably shouldn't work for me as often as it does smile and even if it does draw a lot of current, it just means that the voltage rails will sag like hell. And if something does start to burn, I can always smell it and usually have spare parts. (I've lost a few 10R power input filter resistors on Yusynth projects from me being stupid.)

If I'm feeling either cautious or calm, I'll use the Mutable Module Tester I made awhile ago. (I got the board and chip from adam on this forum.) Helpfully, this can also provide test signals and do some very basic signal analysis of the module's output. (Very basic, but still easier than dragging the scope out.)

The most important thing, by far, however, is to be very, very, very careful with your soldering. Nice, neat, shiny joints, NO solder bridges, components neatly placed.
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