# Problems with my first VCO
**URL:** https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766
**Category:** DIY STUFF
**Created:** [January 23, 2021, 9:37pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766 "2021-01-23T21:37:12Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Ranch](https://lookmumnocomputer.discourse.group/u/Ranch)
#### Post date: [January 23, 2021, 9:37pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/1 "2021-01-23T21:37:13Z")
Hello there.
I have started to work on three modules for a school project, with the deadline of january 31st, but I ran into a problem.
I have recently finished building my first module, LMNC’s simple VCO with the square wave output and pwm. When i went to test it out i have had no signal coming out of the outputs.
I tried trobuleshooting but so far with no succsess. I have cheecked the power supply connections and I think there is no problem there. I tried wiring each of the outputs individually because I thought that maybe i have wired something wrong on the panel, but it didn’t work.
Right now I have how to fix it and I hope I haven’t fried the chips, even though there was no smoke or smell. Since I’m a beginner and have almost no idea what I’m doing, I really need some help!
Thanks.
BTW I didn’t know where to post this so I made a new topic.
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### Author:  [@Caustic](https://lookmumnocomputer.discourse.group/u/Caustic)
#### Post date: [January 23, 2021, 9:48pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/2 "2021-01-23T21:48:14Z")
If you are talking about the super simple oscillator there are a few threads.
TLDR; is usually just that you need to find the right transistor to get the oscillation. So try a bunch of them and see if that helps. 🙂
> [@Troubles with the SUPER SIMPLE OSCILLATOR](https://lookmumnocomputer.discourse.group/t/troubles-with-the-super-simple-oscillator/772/10):
>
> A few threads have discussed problems with this Circuit. Not sure if its because its usually people’s first or that really this reverse avalanche effect that causes the oscillation isnt as consistent as people expect. I skipped building this thing, so i cant say i have any experience with this one. Do you have a multimeter? If se, we can guide you in the process of troubleshooting if you like. Also, are you using new batteries?
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### Author:  [@Ranch](https://lookmumnocomputer.discourse.group/u/Ranch)
#### Post date: [January 23, 2021, 9:55pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/3 "2021-01-23T21:55:59Z")
I’m talking about the CEM3340 vco.
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### Author:  [@CTorp](https://lookmumnocomputer.discourse.group/u/CTorp)
#### Post date: [January 23, 2021, 11:00pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/4 "2021-01-23T23:00:52Z")
Do you have a multimeter?
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### Author:  [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)
#### Post date: [January 23, 2021, 11:01pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/5 "2021-01-23T23:01:23Z")
> [@Advice for troubleshooting 3340 based VCO](https://lookmumnocomputer.discourse.group/t/advice-for-troubleshooting-3340-based-vco/2077):
>
> This is a wiki post; please correct and improve! This is written regarding the 1222 Performance Oscillator module, but similar things apply to the simple stripboard oscillator or other oscillators based on the 3340 chip. For the stripboard version also see If you are not getting good tones from the oscillator, do the following. If with the 1222 you are also not getting good behavior from the tuner, don’t waste time on trying to fix that yet. Get good tones on the outputs first — the tuner won…
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### Author:  [@Ranch](https://lookmumnocomputer.discourse.group/u/Ranch)
#### Post date: [January 23, 2021, 11:30pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/6 "2021-01-23T23:30:28Z")
Right now I don’t, but I plan on getting one asap
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### Author:  [@Ranch](https://lookmumnocomputer.discourse.group/u/Ranch)
#### Post date: [January 23, 2021, 11:31pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/7 "2021-01-23T23:31:50Z")
Thanks, I’ll try to fix it using this.
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### Author:  [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)
#### Post date: [January 23, 2021, 11:37pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/8 "2021-01-23T23:37:20Z")
It’ll be hard to proceed without one.
> [@Multimeter recommendation](https://lookmumnocomputer.discourse.group/t/multimeter-recommendation/716):
>
> Hey guys I’m building the mfos voltage quantizer, got it built and it’s working but I need to tune the voltage steps to be as close to 0.08333v apart as possible. My cheapo harbor freight $5 meter is not cutting it. There seems to be a vast gap between the cheapos and the $600+ Fluke meters. I’m a tool guy and take care of them so don’t mind getting quality that will last but that seems a bit much. What do you guys use? Or what would you get now If you needed a new one? As of now I’m leaning t…
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### Author:  [@CTorp](https://lookmumnocomputer.discourse.group/u/CTorp)
#### Post date: [January 23, 2021, 11:51pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/9 "2021-01-23T23:51:09Z")
Yeah…not a lot of troubleshooting you can do without one, except looking things over. Even the cheapest one you can find would work. I used a $4 or $5 harbor freight meter for six months
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### Author:  [@twinturbo](https://lookmumnocomputer.discourse.group/u/twinturbo)
#### Post date: [January 24, 2021, 10:19am UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/10 "2021-01-24T10:19:58Z")
Did you make all the track cuts on the strip board?
Lets see the PSU…
Post up a couple of Hi-Res pics of the front and back of the strip board.
Rob
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### Author:  [@Ranch](https://lookmumnocomputer.discourse.group/u/Ranch)
#### Post date: [January 24, 2021, 3:04pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/11 "2021-01-24T15:04:23Z")
Yesterday I tried to get an isolated triangle output(wich probably was not smart), but it still didn’t work. I think I did the cuts on the stripboard right if you mean the break ups of lines between the chip sockets. And yes it kinda looks all messed up because I tried to disconnect wire and reconnect them, etc. Also the resistors have different Wattage values because when I ordered the parts I didn’t realize that. And lastly I moved the power socket(don’t know what it’s called) to another spot. hope this helps.
 
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### Author:  [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)
#### Post date: [January 24, 2021, 3:17pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/12 "2021-01-24T15:17:02Z")
Probably not the source of any of your problems, but it is recommended to connect your ground to all six power header ground pins, not just two of them.
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### Author:  [@Ranch](https://lookmumnocomputer.discourse.group/u/Ranch)
#### Post date: [January 24, 2021, 3:21pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/13 "2021-01-24T15:21:50Z")
ok i ill do that just in case
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### Author:  [@twinturbo](https://lookmumnocomputer.discourse.group/u/twinturbo)
#### Post date: [January 24, 2021, 5:04pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/14 "2021-01-24T17:04:57Z")
Power input looks right,
Are the extra set of cuts and associated jumpers from a previous attempt?
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### Author:  [@Ranch](https://lookmumnocomputer.discourse.group/u/Ranch)
#### Post date: [January 24, 2021, 5:07pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/15 "2021-01-24T17:07:47Z")
yes, i messed up the first time
also i just got a multimeter, noob question is the circuit in ac or dc?
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### Author:  [@Dud](https://lookmumnocomputer.discourse.group/u/Dud)
#### Post date: [January 24, 2021, 5:26pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/16 "2021-01-24T17:26:20Z")
DC +12V / GnD / -12V power supply for modular
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### Author:  [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)
#### Post date: [January 24, 2021, 5:39pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/17 "2021-01-24T17:39:56Z")
Power is DC (it’s a flat constant value, plus or minus). Audio signals and some control voltages are AC (they oscillate above and below a central value), but the voltages mentioned in the linked posts above are DC.
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### Author:  [@CTorp](https://lookmumnocomputer.discourse.group/u/CTorp)
#### Post date: [January 24, 2021, 6:05pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/18 "2021-01-24T18:05:31Z")
 
There’s a couple other spots that look suspicious too but hard to say. Make sure you don’t have any solder bridges where you shouldn’t. There should be a mode called continuity on your meter you can check if you have a connection
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### Author:  [@Ranch](https://lookmumnocomputer.discourse.group/u/Ranch)
#### Post date: [January 24, 2021, 6:22pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/19 "2021-01-24T18:22:08Z")
Those two spots didn’t conduct but, i found another spot that did and fixed it. Also i’m had a thought that maybe my 3340 chip doesn’t work. How could i make a simple circuit to test if it works? but thanks for the tips everyone.
I checked how much power there is on the stripboard by measuring +12v and -12v connections,and on the multimeter it showed up as 10,06v, could that be the problem?
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### Author:  [@CTorp](https://lookmumnocomputer.discourse.group/u/CTorp)
#### Post date: [January 24, 2021, 6:30pm UTC](https://lookmumnocomputer.discourse.group/t/problems-with-my-first-vco/2766/20 "2021-01-24T18:30:29Z")
Take out the 3340 and plug in the module. check the voltages at where pin 3 and 16 would be, those are the power supply pins for the 3340
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