Hopefully just led resistors?
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Yeah. I realised in time thankfully, so had to desolder them and bodge on the correct values. Hopefully it won’t result in kaboom.
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I’ve now managed to blow up two of these. Starting to see maybe why that power supply isn’t so great. First was totally my stupidity. The second was because I unplugged it and plugged it back in while it was switched on. Both times it was the -12V one. Guessing it doesn’t really like being hooked up that way.
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Picked up one of those cheapo little scopes and hit the ground running trying to do some PWM to CV experimentation, and then built a little test platform module to streamline the process.
Spent the better part of a week agonizing over 1. some insane jitter I was getting and 2. some insane waveshaping that, looked really cool, but was not at all the desired result.
This sparked a quest to learn how PWM works in microcontrollers, the difference between AVR and STM32 MCUs right on down to the timer registers of each, and several days of legitimate despair in an attempt to correct whatever PWM phase issue was causing me this existential dilemma.
The waveshaping legitimately dumbfounded me, because I adapted the code to use a 12-bit DAC instead of a pin for PWM to see if it was something about the hardware timer that was wrong, and it looked exactly the same!
Well it turns out that my pots were soldered into the test platform module badly causing the jitter, and that on a scope things look very different when it’s set to AC vs when it’s set to DC, fixing the apparent waveshaping issue.
The upside is a newfound knowledge and respect for the intricacies of hardware timers in microcontrollers.
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had an auto mechanics teacher back in the school days who always said " check the simplest things first " I have personally found many times over how true this philosophy is .
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Your auto mechanics teacher would have made an excellent experimental nuclear physicist.
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Today’s dumbassery. I know the difference between AC and DC. I know they are not the same. I know the Frequency Central MicroBus needs AC not DC. I bought what was advertised as an AC adaptor. I saw the polarity symbol on the plug when it arrived but didn’t put 2 and 2 together… and spent two hours troubleshooting then building another one of the MicroBus incase I had messed something up.
But of course, the PSU was DC, not AC. I am an idiot.
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…and also “check the area where fiddled around last time” 
that’s why it’s always good to have logbooks (I do have logbooks for all my motorcycles and most of the DIY projects 
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I keep a handwritten notebook or pad* covering every project, new machine, tech, software etc. Usually just in the early stages as I learn and then an update now and then as I add stuff.
*“Personal Analogue Device”
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My LMNC Dual VCA wasn’t playing ball. Me being me I decided to reflow all the joints on the jacks. Plugged it back into the case and tested it…still nothing. While it was plugged in I noticed that if I tapped/moved the output jack and turned the volume way up there was a slight noise. I pulled the faceplate off and visually checked everything. It looked fine. So I decided to replace the TL074’s. Bingo Bango all fixed. Not sure how or why but I must have let the magic smoke out of the IC’s.
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there were bad 74’s going around , several of us were bitten by that one .
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meh, thats what wires are for 
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There’s about 11 ground pads on the main board and about 12 on the jacks/pots board, which is pretty doable if you have the patience and suitable fine wire. On the other hand, I probably could not sell the extras of these boards, so probably could not sell the extras of the panels either, and it might make more financial sense just to get the PCBs redone.
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A wee drill and some new via’s might reduce some wiring.
I caught one the other day , JLC mentioned text and a short circuit.
On inspection I found the drawing details box had text in F.Cu and the PCB was over the box
Managed to correct it and upload a revised version before engineering committed it to production…
It also caused, or helped me spot a couple of net wires that were not connected. I had to delete all copper and redoo the routing and fill to fix it.
Rob
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You know how you can look at something for 2 years and never see it…
Added that to my checklist ( Cheers ), usually the auto router either finishes correctly or it does not. I think the odd text must have screwed it up.
Rob
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In my defence I was trying to get 5 different project and 11 boards ( 3 not mine ) off to JLC in one swoop over the weekend so it was a bunch of work. Hopefully it’s the only defect and caught in time … Just hope my sons 3 boards turn out ok, not even electronic he just wanted engineerd pannels and it cost him £55 for the pleasure!
Rob
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