So I’m in a bit of a jam, and don’t know how to get out. Therefore, I am turning to you wonderful humans of the internet for perhaps even a tinge of inspiration to get me in the right direction.
I recently acquired a Dreadbox Dysmetria, so I can get into doing some DIY, and maybe build up the skill confidence to start making my own bits. I’d already bought and built Dysphonia, and though that was a much easier build, I thought this one seemed pretty easy, too.
When it arrived, I diligently put it together, and yet I’m having issues. For starters, the digital sequencer section doesn’t work at all, despite seeming to get power no problem. Also, the analog section is a little wonky. The 1v/Oct test point (which should be able to be adjusted to read a proper value of 8) reads 10.84, and at first, the pitch was okay, but it slowly drifted higher. As in really high pitched. Then it started not producing sound at all. The Mixer and Filter sections seemed to operate okay, but now it seems they’re all being strange, too. The OSC chips are the SSI2130, and it is receiving a clean 2.5V reference voltage, and seems to measure out okay. The Filter is the ssi2164, which also seems to measure out okay. I’m not sure what has got me in this conundrum, but I’d love to sort it out. If you need more info from me, let me know and I’ll get it. To those who want to tackle helping me, thank you in advance, truly you are legends.
Welcome Sean! Nice to see another DIY enthusiast 
First of all, it’s always helpful to see some picture of your work, maybe we can even spot the issue right away.
I don’t know how much experience you have with electronics but the most common issues are:
- Mix-up of components: two resistors may look the same, yet they can have totally different values. I for example often confuse orange with red on some types of resistors, and if it’s the third stripe, it’s a factor of 10 in resistance value
check if you have placed them correctly, maybe something is swapped - Orientation of components: I don’t know how well the PCB is annotated, but a transistor can easily be installed in the wrong direction. Also components with polarity (diodes, electrolytic caps, LEDs) are a common source of error.
- Bad soldering: yes, this is fairly obvious and can be hard to spot. If you solder lead-free (which I personally prefer due to good reasons), the solder blobs are not shiny and can be cold or cracked, without being noticed. I’d recommend to look through all of them and resolder when in doubt.
- The last thing on my “common issues” list is: bad components. It can always happen that a component is already broken when you use it, or was fried due to some other errors (see e.g. the other examples above
).
I recommend the following workflow, which I personally use with a fairly good success rate, but I also spend a significant amount of time with debugging, you are not alone, we are all humans
- Clean the whole PCB/stripboard with isopropyl alcohol or something similar to get it clean, before you solder anything
- Measure each(!) component before you put it on your stripboard or PCB
- If using a stripboard, make sure check that the stripes are not electrically connected
- After soldering and before connecting the circuit to a power source, do connectivity checks of well known points: check that the GND is not shorted to + or -, check if the supply and ground pins of all ICs are connected to the correct supply rail.
…and last but not least: if you have a (lab) power supply where you can limit the current, set it to a very low value (a typical module will not draw more than 20-50mA or so, of course depending on the type) and watch what happens. This way the risk of frying things can be reduced by a fair amount. If you see that the current reaches the limit, think twice and increase it. If in doubt, think again
Thanks so much for the reply!!!
In regards to pictures, I’ll post some today or early tomorrow morning. I have a funny feeling it’s a case of a really obvious and embarassing mistake on my part. That’s about my luck right there. 
In regards to experience, I took some electronics in Uni about 12 years ago. So I’m quite rusty. And it was all textbook stuff, not hands on. I’ve been trying to get into the hands on part in a big way. I like to think I can solder a joint, and I usually get nice shiny fillets, but sometimes I don’t, and occasionally have a hard time fixing them, but I always try to leave them better than I saw them. Generally, if I notice dull, cracked or pitted joints I try to fix them as best I can. I do solder lead-free, as I don’t like the idea of lead fumes, regardless of how superior a product it may be, or how much ventilation I have going on. But that’s not to say that I’m good at soldering. Often I wish I had a buddy near me that knew this stuff that could take the time to show me, but due to some anxiety issues and whatnot I hermit up pretty hard, and I’m pretty awkward, so I don’t think that’s going to happen anytime soon.
In regards to components, on this particular build everything was labelled pretty well, and was pretty clear. I measured a couple random resistors on every strip (I know, I should have measure every one), and they all matched what they were supposed to be, and they all got the coloured band inspection. But knowing me, it’s entirely possible I messed something up. I was short one 220p capacitor in the kit, but I had a capacitor of the same value kicking around, so I used it. I also didn’t receive the 49k9 resistors that the kit was supposed to have, so I used some that I had kicking around (fresh from a tape, and checked as per above).
In regards to parts orientation, the pcb had markings to help with orientation, so I think I got that part pretty good, too. But even without them, I looked up the pin definitions for the transistors, etc… So I think that should be okay. I measured the voltage outs on the ICs, and they all seem to be doing what they’re supposed to be. They’re receiving proper voltages, etc… I’ll post some pictures and whatnot. Unfortunately, I don’t have a bench power supply. I’m working with a very bare bones set up, under the personal limitation of not getting a nice setup until I actually see if my silly brain can actually handle this stuff.
TL:DR I think the parts orientation part isn’t my issue, but I could be wrong. I highly suspect it’s a solder joint/faulty IC thing, or perhaps a capacitor or somesuch that isn’t working properly. My power rails are receiving proper power amounts, but somewhere between there and the patch cables things start to deteriorate. >_< Are there any spots that would help that I took some readings on and included in the pictures?
It’s hard to tell, but something like this:
seems to be a temperature problem to me. I have never seen a SSI2130 in action, but I assume that they have a fairly good temperature compensation, which means that if the sound is drifting away (given that the 1v/Oct input is still constant) the chip is probably getting way hotter than it can handle.
It’s just a guess, but you should try measuring the current through both the positive and the negative rails, and also check if any of the components get hot (you can use isopropyl alcohol, which evaporates quickly on hotter components).
tamasgal,
I’ve been unexpectedly busy the past few days, so I haven’t had the opportunity to sit down with it. In regards to the drifting, I think that may have been a miscommunication on my part. It doesn’t drift as it is receiving CV. It’s more that it seems the CV I’m sending it was normal, but then at some point when I started it up, it suddenly became much higher pitched, with the CV values staying the same. Adjustment of the 1V/Oct trimpot produces no change in this issue, nor does it get the 1V/Oct reading down to 8V, where the build guide says it should be. None of the ICs thus far are overheating, nor are they dead cold. They seem to be operating within normal ranges, so I suspect it’s a really dumb error on my part. Once I get some free time in my workspace to work on it I’ll be posting some pics and some readings to see if maybe that helps the troubleshooting process.
Update
I noticed a couple of the 100nf caps were shot, so I’ll be replacing them this weekend, and going over a few other potential areas of interest. I’m tracing the path of the circuit on the 12V rails, and the CV traces, to see if I can spot where the issue is. Hopefully it yields some results. To be honest, I’ve been far too busy with life to have time to take a look at it. Now I can finally spend an evening or two with it, and see what happens.
Might be a similar situation, but I have the Dysmetria working but only the analog side. None of the digital controls are working. They were before I took apart for tuning and aren’t now. No led lights, no sequencer, no pitch control, etc. but the analog sounds all come out just fine.
Tested and it all gets power. Bad chip? What else could it be?
How were the 100nf capacitors shot? What causes them to fail?