First cMoy NO SOUND hellllpp!!!

[Fred_fred2004]

If you are making this from Tangents instructions (attached) it looks like the rail splitter capacitors are in backwards and the negative(black) lead from the battery appears to be connected to the (+) side of the rail splitter cap.

You need to check your rail splitter voltages I can't see how it can be working the way it appears in the photo.

Compare your pic to Tangent's and you can see the error
cheers

 

[Pars]

Quote:

Originally Posted by GR/NDER /img/forum/go_quote.gif This is where Im at now after following everyones suggestions. Still doesnt work.

Is the opamp a new one, or is it one that has been in with the battery reversed? Any opamp that was in there with reversed power is most likely toast.

 

[Pars]

Quote:

Originally Posted by Fred_fred2004 /img/forum/go_quote.gif If you are making this from Tangents instructions (attached) it looks like the rail splitter capacitors are in backwards and the negative(black) lead from the battery appears to be connected to the (+) side of the rail splitter cap. You need to check your rail splitter voltages I can't see how it can be working the way it appears in the photo. Compare your pic to Tangent's and you can see the error cheers

The caps were in correctly in the 1st pics (page 1)... he must have switched them. The battery appears to be wired correctly now ( the + side should be going to the left cap, and the - side to the right cap). Flip the caps back the way they were.

Also, it looks like you rewired pins 1 and 4 on the pot. You currently have a blue wire on 1 and a red on 4... they were correct before.

 

[GR/NDER]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif The caps were in correctly in the 1st pics (page 1)... he must have switched them. The battery appears to be wired correctly now ( the + side should be going to the left cap, and the - side to the right cap). Flip the caps back the way they were. Also, it looks like you rewired pins 1 and 4 on the pot. You currently have a blue wire on 1 and a red on 4... they were correct before.

Ok I switched things back like you said.

Now nothing happens. The LED doesnt even light up any more, like it did before i switched them.

The battery also is getting hot.

 

[Pars]

Pics?

You

• Switched the electrolytic cap polarity back to the way they were in your first pics?
• You left the battery wired per your last pics (red lead (+) going to the left side, black to the right side from switch)?
• Swapped pins 1 and 4 on the pot (though this would not keep amp from working, would just flip L and R channels).

Battery getting hot isn't good as it indicates it is trying to drive a short. LED is less of an issue (probably just a wiring or polarity issue).

EDIT: also, you didn't answer the question in post 32.

 

[GR/NDER]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Pics? You Switched the electrolytic cap polarity back to the way they were in your first pics? You left the battery wired per your last pics (red lead (+) going to the left side, black to the right side from switch)? Swapped pins 1 and 4 on the pot (though this would not keep amp from working, would just flip L and R channels). Battery getting hot isn't good as it indicates it is trying to drive a short. LED is less of an issue (probably just a wiring or polarity issue). EDIT: also, you didn't answer the question in post 32.

Hey Pars, yes I think the amp is ok. I havent seen it go up in a puff of smoke yet.

Here is a picture.

 

[Pars]

I think you have the + battery lead going to the switch, but your uninsulated connection is awfully close to that resistor lead which goes to virtual ground. I attached a mark up of your pic, plus a shot of one of Tangent's previous files for building the Cmoy.

I would remove the opamp, and then measure the voltages from virtual ground to pin 8 (V+) and pin 4(V-) of the opamp socket. Verify that you have + 4.5V or so on pin 8, and - 4.5V on pin 4 (red lead on pins 4 and 8, black lead on virtual ground). Also note whether the battery gets hot with the opamp out or not.

 

[Fred_fred2004]

I agree with Pars you need to be checking voltages put the opamp away until you get the power section sorted, that's where the problem is.
Just noticed that led is very close to the headphone jack is there a short?

 

[GR/NDER]

Thanks pars.

I dont have a voltage tester good enough to put to use yet. If we cant figure anything out I'll go get one.

I cleared that section of wire from the (+) side of the battery. It wasnt the problem.

I cleaned up some solder on the bottom of the board, and wallah, LED lights up, and the battery is cool as a cucumber.

No sound still. Maybe Ill buy another OP amp and see if this one burned out.

EDIT: I can hear the click ON/OFF, but no audio.

 

[Random Murderer]

check the connections on the jacks.

 

[DKJones96]

It is possible that you have fixed your problem and don't even know it. I don't know about others here but I have NEVER been able to get the TL082 to operate on a single 9v source. I tried this on my cMoy and the lowest voltage I could run and hear something was 12v and it sounded horrible. It clipped badly and that was the highest output source I had at the time.

I use the TS922 from ST because it has an operating voltage range of 2.7-12v letting me run a cheap single cell lithium 3v source.
**EDIT** It is also in their free sample program.

 

[Pars]

Quote:

Originally Posted by DKJones96 /img/forum/go_quote.gif It is possible that you have fixed your problem and don't even know it. I don't know about others here but I have NEVER been able to get the TL082 to operate on a single 9v source. I tried this on my cMoy and the lowest voltage I could run and hear something was 12v and it sounded horrible. It clipped badly and that was the highest output source I had at the time. I use the TS922 from ST because it has an operating voltage range of 2.7-12v letting me run a cheap single cell lithium 3v source.

You could be right. In looking at both the TI datasheet as well as the National datasheet, I don't see a min. voltage listed. A graph in the National datasheet suggested something slightly less the +/-5V, which would put it right on the edge of a single 9V batter. I've only actually used the TL071/81s as servoc opamps, and that was always at +/-15Vdc.

At any rate, before plugging any opamp in, the OP needs to verify the pin 8 and pin 4 voltages (both magnitude AND polarity).

 

[Random Murderer]

Quote:

Originally Posted by DKJones96 /img/forum/go_quote.gif It is possible that you have fixed your problem and don't even know it. I don't know about others here but I have NEVER been able to get the TL082 to operate on a single 9v source. I tried this on my cMoy and the lowest voltage I could run and hear something was 12v and it sounded horrible. It clipped badly and that was the highest output source I had at the time. I use the TS922 from ST because it has an operating voltage range of 2.7-12v letting me run a cheap single cell lithium 3v source.

it depends on the situation and the chip itself.
i've seen two tl082's run at +9vdc and the rest at +12vdc or more.
my cmoy uses a tl082 and two 9v batteries...
i say the op should check his pin 4 and 8 voltages as well. if it's less than 12v(and it is if he's running it on a single battery) he should replace the battery, add another battery, or run it from a wallwart to be sure...

 

[Pars]

Yes, but he really needs to verify the polarity as well (pin 4 should be -, pin 8 +). If not, he'll smoke another chip.