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CGS114 Not working correctly

CGS114 Not working correctly

2015-06-12 by jorgen.vandeburgt

Hi All, I've seen this behaviour with others who had trouble with this circuit on the forums, but unfortunately no solution:


I've built a Quad Slope for eurorack, and it's not entirely disfunctional, but the LEDs are always on, and self-oscillation does not work for either of the four parts. The trimmers don't do anything to solve this behaviour :S Anybody have an idea? And yes, the trannies are in backwards all the way across both boards.


Second problem which I don't understand is that one of the bipolar outs shorts the entire modular, even making the power supply turn off entirely (luckily it's a protected supply).

Re: CGS114 Not working correctly

2015-06-12 by jorgen.vandeburgt

Ok this is interesting. Problem #2 persists after I disconnect the wire from D to the problematic jack. Since only the ground line is connected, what's going on? None of the other jacks that are on the same ground line show this behaviour :S

Any input on the lack of oscillating BTW?

Re: CGS114 Not working correctly

2015-06-12 by Ken Stone

It is almost certainly a construction error on both counts. It's hard for me to say what is going on when I have never seen the fault condition myself. "Transistors all in backwards" worries me because you did not specify the type of transistors you are using. They may not need to be in backwards. Correctly built, the circuit should not be able to short out a power rail.
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On Fri, Jun 12, 2015 at 9:03 PM, jorgen.vandeburgt@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

Ok this is interesting. Problem #2 persists after I disconnect the wire from D to the problematic jack. Since only the ground line is connected, what's going on? None of the other jacks that are on the same ground line show this behaviour :S


Any input on the lack of oscillating BTW?




--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS114 Not working correctly

2015-06-12 by Jorgen Van De Burgt

It's 3904 and 3906s all round as specified. I used a component kit from Elby.

Coincidentally, the one problematic jack is the only different one from all the others. Still, that's not what is giving me the other issues...



Op 12 jun. 2015 om 13:51 heeft Ken Stone otherunicorn@... [cgs_synth] <cgs_synth@yahoogroups.com> het volgende geschreven:

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It is almost certainly a construction error on both counts. It's hard for me to say what is going on when I have never seen the fault condition myself. "Transistors all in backwards" worries me because you did not specify the type of transistors you are using. They may not need to be in backwards. Correctly built, the circuit should not be able to short out a power rail.

On Fri, Jun 12, 2015 at 9:03 PM, jorgen.vandeburgt@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

Ok this is interesting. Problem #2 persists after I disconnect the wire from D to the problematic jack. Since only the ground line is connected, what's going on? None of the other jacks that are on the same ground line show this behaviour :S


Any input on the lack of oscillating BTW?




--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS114 Not working correctly

2015-06-12 by Ken Stone

The first step is to check voltages - at the power pins of the chips. Feel about to make sure no part is getting hot.
Make sure you have the diodes all the right way around, Make sure you haven't mixed the zener with a regular diode.
Second - check the voltages at the outer tabs of the pots. Some will be at 0V or power rail voltages. Some will match the voltage you are feeding into the inputs. Check that the voltage at the wipers change when you move the pots. (for the CV ones, you obviously need to feed a voltage into the CV inputs.)
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On Fri, Jun 12, 2015 at 10:46 PM, Jorgen Van De Burgt jorgen.vandeburgt@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

It's 3904 and 3906s all round as specified. I used a component kit from Elby.

Coincidentally, the one problematic jack is the only different one from all the others. Still, that's not what is giving me the other issues...



Op 12 jun. 2015 om 13:51 heeft Ken Stone otherunicorn@... [cgs_synth] <cgs_synth@yahoogroups.com> het volgende geschreven:

It is almost certainly a construction error on both counts. It's hard for me to say what is going on when I have never seen the fault condition myself. "Transistors all in backwards" worries me because you did not specify the type of transistors you are using. They may not need to be in backwards. Correctly built, the circuit should not be able to short out a power rail.

On Fri, Jun 12, 2015 at 9:03 PM, jorgen.vandeburgt@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

Ok this is interesting. Problem #2 persists after I disconnect the wire from D to the problematic jack. Since only the ground line is connected, what's going on? None of the other jacks that are on the same ground line show this behaviour :S


Any input on the lack of oscillating BTW?




--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>




--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS114 Not working correctly

2015-06-15 by jorgen.vandeburgt

So, good news and bad news. The good news is it's fixed. The bad news is that I'm an idiot. I thought I'd connected a ground line on all the jacks, but I'd connected the wrong terminal meaning all jacks were connected all the time. Removed these connections and now I'm golden... How bad is it to not ground the jacks? It'll be a big hassle to do that now that it's all working.

Re: CGS114 Not working correctly

2015-06-15 by Ken Stone

As long as the module is using the same power supply as your other modules, the jacks don't need grounding. After all, that is how banana jacks work.

Cheers,


Ken
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On Mon, Jun 15, 2015 at 7:34 PM, jorgen.vandeburgt@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

So, good news and bad news. The good news is it's fixed. The bad news is that I'm an idiot. I thought I'd connected a ground line on all the jacks, but I'd connected the wrong terminal meaning all jacks were connected all the time. Removed these connections and now I'm golden... How bad is it to not ground the jacks? It'll be a big hassle to do that now that it's all working.




--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS114 Not working correctly

2015-06-15 by Jorgen van de Burgt

Cool, saves me a lot of work! Thanks for the awesome module Ken (you and Serge, and Clarke for the panel) :)
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On Mon, Jun 15, 2015 at 1:02 PM, Ken Stone otherunicorn@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

As long as the module is using the same power supply as your other modules, the jacks don't need grounding. After all, that is how banana jacks work.

Cheers,


Ken

On Mon, Jun 15, 2015 at 7:34 PM, jorgen.vandeburgt@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

So, good news and bad news. The good news is it's fixed. The bad news is that I'm an idiot. I thought I'd connected a ground line on all the jacks, but I'd connected the wrong terminal meaning all jacks were connected all the time. Removed these connections and now I'm golden... How bad is it to not ground the jacks? It'll be a big hassle to do that now that it's all working.




--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>


Re: CGS114 Not working correctly

2015-07-10 by jorgen.vandeburgt

So still not perfect. One quart has a very limited rise. It oscillates until I reach about the 20% mark of the rise button. After that it stops abruptly. The other quarts work fine, this is the only one that has this. I've measured the pot and it's working fine and outputting 0 - 12 volts. Any ideas?

Re: CGS114 Not working correctly

2015-07-10 by Ken Stone

Look for a construction error. No idea specifically what, but swapped wires, solder dags between pads, overenthusiastic soldering lifting pads on the circuit board, which can be a problem on single sided PCBs. Wrong parts (PNP instead of NPN etc). Missing links.
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On Fri, Jul 10, 2015 at 9:23 PM, jorgen.vandeburgt@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

So still not perfect. One quart has a very limited rise. It oscillates until I reach about the 20% mark of the rise button. After that it stops abruptly. The other quarts work fine, this is the only one that has this. I've measured the pot and it's working fine and outputting 0 - 12 volts. Any ideas?




--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

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