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Cgs synth

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Message

Re: Smoke

2012-11-18 by Ove Ridé

On 18 November 2012 10:16, fuyuhiko <hiko_goldenballs@...> wrote:
> Hi there.
> This is not a question for the CGS circuits but is for an ADSR envelope
> I've been making.This is the schematics.
>
> [http://yusynth.net/Modular/Commun/ADSR/ADSR-V2-sch-thumb.gif%5d
> <http://yusynth.net/Modular/Commun/ADSR/ADSR-V2-sch.gif>
> Even though I've succeeded to make it on solderless breadboard, I now
> suffer from smoke on the both 10Rs of the power supply. As soon as I
> connect the power it happens.To be honest when I finished soldering
> first time it worked but in an odd way, then I realised that I hadn't
> connected -15V to the pin 11 of the TL074 and connected +15V to pin 5. (
> very careless mistakes) This time there was not any smoke but since I
> connected again.
> I've checked all connections but no idea of how to make it work since
> I've made the same power circuit four times.
> Does anyone suspect any particular parts? Or should I solder it from
> scratch again?
> Sorry for the question that is not for the CGS.
> Kind Regards

Obviously, you have a short somewhere which makes current conduct from
+15V to -15V. The first sanity test question is, are you sure you
haven't swapped the positive and negative power supplies, now or at
any point during the build? This could potentially immediately destroy
all of the chips. The discrete transistors are also vulnerable, but
they have big resistors in series in all directions and wouldn't be
able to cause this kind of major failure.

My advice would be to remove the 555 and the TL074 and first try
powering up the board without them, then adding them one by one and
see when the fault happens. If the fault happens without either of the
chips present, the problem is different. Either just a dumb short
somewhere, or way too small resistor values somewhere causing what is
effectively a short, or reverse polarity of the polarized capacitors,
C1 and C2, which would cause them to conduct a DC current. If the last
option is the cause of your error, those will likely start emitting
smoke as well at some point.

In case like these, it's useful to have a bench power supply with
current limiting, so you can detect a fault like this without having
to burn components.

--
/Ove

Blog: <http://blog.gg8.se/>

"Here is Evergreen City. Evergreen is the color of green forever."

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