Is there any Powersupply you could recommend when going standalone ?
How many mA ?
500 ? 1000 ? x ?
GOT IT ! Just took a 500mA one cause i realized that might do it by far.
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my friends!
the heat has driven me back into the basement to my soldering desk and work through this module backlog
first up was the megadrone, all working fine apart from one osc just isnt powering
reflowed the whole thing, trans and diode are in the correct way, swapped out for a mosfet i knew was working and now im stumped.
anyone got any steps for a more in depth troubleshooting on the osc circuits, or maybe something down the chain that could be blocking number 7 from firing. i get absolutely nothing from it.
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Do you have a multimeter? Could be a good time to learn how to debug with a multimeter.
oh yeah i do, and can debug when im led in the right direction, but i generally have no idea what im looking for and where im looking for it.
could maybe check the voltages on the others oscs and try and see where they dont match?
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so i did exactly that, checking the voltages and got some irregular readings on osc 7, the one that doesnt work
but i dont know what to make of the readings, the mosfet is the only component that has the same reading as the other oscillators, the others are pretty wild
especially the transistors, the reading keeps fluctuating from high to low
Sounds like what you are picking up is akin to oscillation. Can you go into detail about what you mean when you say its not powering?
Are you saying that the reading you get on osc 7’s mosfet is similar to the other osc’s mosfets?
yeah for example
pin 1 on all mosfets reads about 3.7v
pin 2 is diff for all
1 - 1mv
2 - 4mv
3 - oscillating between 10 and 150mv. moving chaotically
4 - 2mv
5 - 2mv
6 - 1mv
7 (doesnt work) - 0
8 - 4mv
9 - 7mv
10 - 3mv
pin 3 reads 0 for all
all the transistors measured 7.8v at the pin in the square hole but osc 7 dives from 500mv to 5mv over about 15 secs then stays there for a minute and then shoots back up
all diodes read 102mv on the line side, and the non line side about 300-350mv apart from osc 7 which reads 1mv
all electro capys read 7.8v on positive leg but osc jumps and dives like the transistor, guessing they are directly connected
ok now have replaced every component in osc 7 and still nothing, felowed the control section too
maybe a faulty pcb?
Maybe, or maybe a short or disconnection created during all the soldering/desoldering. Turn off power and check continuity between pads.
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well it didnt work before the desoldering . . . .
but!! i just checked continuity and there are some oddities R6 the 3.3k resistor isnt reading as connected to the tune pot or the transistor, so a dead line there
also R8 the 1m resistor is showing odd coninuity with the level pot, its showing connection to pins 2 and 3, whereas all the other osc circuits are showing as connected to pins 1 and 2
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R8 is supposed to be connected to pin 2. If it shows as also connected to pin 3 it’s presumably because the pot is fully clockwise, while it’d be connected to pin 1 if it were fully counterclockwise.
Curious that both ends of the resistor are not connected. You could try reflowing those two solder joints one more time. If it still shows disconnected you’d need to solder a wire from one end of the resistor to the transistor and another wire from the other end of R6 to the pot.
Is the transistor connected to the capacitor (as it should be)?
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ah yeah good info on R8, makes total sense
good spot on the cap, hadnt checked that one and no, no connectivity from the cap to the transistor
also rechecked R6 and its only the side going to the pot thats not connected
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One side of R6 is supposed to connect to both the cap and the transistor — if the cap and transistor are not connected then which does R6 connect to?
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ah i didnt check, but it did connect to the transistor so im assuming the connection at that point and the cap was dead
i just hardwired the cap and transistor plus R6 to the pot and it now works!!
continuity! thats for giving me the nudge on that, i was at a loss of what the next step was, felt pretty good getting into the schematic and investigating, lucky its such a simple circuit
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So since I’ve built my megadrone, just one oscillator has been fluctuating in a nasty way, while the rest are good
You may have to turn this video up a lot, for some reason it seems VERY quiet.
I’ve replaced essentially every part (aside from the diode) and checked all continuity, and Ive tried resoldering the joints but it still happens.
The voltage across the transistor is fluctuating a bit as well as the voltage across the tuning pot, but the pot doesnt fluctuate in resistance when I test it,
the only odd thing is that the resistance across the 47k is ~9k ohms as opposed to the usual ~12.7k on the other oscillators but I believe thats because I have a 5k tuning pot in this one (i accidentally built it with an 100k originally and had no 10k leftover.) ill add one to my next order
also voltage from the 3k3 to pin 3 of the transistor is fluctuating.
Ive tried three different transistors in this now but maybe theres some solution you guys could help with
it doesnt seem to have to do with the mosfet or any of the level circuitry as that part is all stable
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Hey ho to the megadroners !
All Oscillators work and do what they should, but somwhow the master-tune knob has no effect at all… Did any one encounter this situation and know whats up / how to fix that ?
Best wishes and kind regards !
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Hello everyone!
I finally got to sourcing parts/building the 10osc megadrooooone. But for some reason it does not make any sound. I have 12v at the pins of LM386 amp but the oscillators don’t seem to be oscillating. The LEDs will change intensity when the tune knobs are turned, but thats about it.
I was looking for a place to start troubleshooting, this is my first DIY synth project and not sure where to start other than I’ve tried eurorqack power and a 12v wall wart style supply thinking maybe it was a power issue.
Thoughts on where I should start to troubleshoot?
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