TPA3008D2EVM static noise?

Thanks for your answer!

I'm new to this whole electronics area, so if you can specifiy what resistance that would be suitable, and where to put them, I would be really glad!

Thanks again for the quick reply to my post!

Dan,

Place a 1k resistor between the RINN/RINP and LINN/LINP. Put them between the input coupling capacitor and the input pins on the amp - I have attached a schematic for reference.

Let me know if this helps!

Regards,
Ian Williams

Im not comfortable with soldering between the IC and C1/C2 since they are surface mounted. (red arrow) Is it possible to place the resistor at the input pins? (green arrow)

http://i234.photobucket.com/albums/ee132/fizz_upptaget/DSCN6394-1.jpg

Dan,

You could solder a through-hole resistor to the leads on the right side of C1 and C2, and another at C3 and C4. This should be pretty straightforward, and you can clip the leads of the resistors to be shorter if you want a cleaner look.

Regards,
Ian W.

It sounds simple enough, i hope that my shaky hands are up to the task, the components are so darn small ... =)

Are the caps (and amp IC) heat sensitive?

Dan,

I understand your hesitation - becoming comfortable with soldering surface-mount components takes a bit of time, a few fried boards, and a few burnt fingers. In general, it helps to have a microscope available when you're dealing with surface mount, but in this case you should be okay without one. Make sure to use solder flux, it is your friend! =)

The parts are heat sensitive past a certain range, but the main thing you need to worry about is for your hand to not slip and accidentally touch the soldering iron directly to the IC. The caps are pretty robust and easy enough to swap out if you damage one. Also take care around the traces on the board. Just make sure you're applying your heat to the solder pads on the sides of the caps, and you should be good to go!

Good luck,
Ian W.

Well, if it fails completely, would'nt it be possible to replace those four caps with a little piece of wire, and then use regular caps and solder them between the input terminals in the case and the input pins on the amp circuit board?

http://i234.photobucket.com/albums/ee132/fizz_upptaget/123.jpg

well, that was the best I could do ... [:D] ... I always though the tip of my soldering iron was kind of small but now i know better ...

the result, less noice, or hum, but its still there ... is the solution to try a resistor with a different value?

Dan,

Your soldering job is fine! However, if you're still seeing noise in that channel you can try soldering a 1k from each input to GND, instead of a 1k across the neg/pos sides of each input. So in this case, you would have 4 1k resistors, soldered from the right side of the input caps (like before) to the nearest available ground connection. You might have to solder a wire to a nearby ground and then connect the resistors to that wire.

As for the value, the 1k should be fine.

Regards,
Ian Williams

Thanks for the answer once more!

I'm gone try the second solution on the other channel first, I guess there's no problems doing so?

Dan,

There's no problem at all trying it that way. In fact, doing that you can compare which gives you the better result. Just don't forget to solder a 1k from both INP to GND and INN to GND on that channel.

- Ian

http://i234.photobucket.com/albums/ee132/fizz_upptaget/DSCN6502.jpg

Well, now I've fixed the other channel. The excess lead (or whatever is is nowadays) that you see on the pic, on C3, is removed.

The noice is a lot less, but i think that the first one I did reduced the noice more ... THis could though de due to poor connection between the copper wire (might removed to little of whatever coating it has) and GND. Gone redo that and try again.

Thank for the help!

Dan,

Are you using solder flux? Putting some solder flux around the pads/leads you're about to solder helps greatly in eliminating excess build-up and prevents solder from getting where it shouldn't. I'd highly recommend it for any soldering projects in the future.

I'm glad that you're seeing some progress with this. Do you have access to an oscilloscope? Is there any way you could send me a capture of the output waveform with the noise?

Thanks,
Ian Williams

http://i234.photobucket.com/albums/ee132/fizz_upptaget/DSCN6512.jpg

well, that kind of ended this project .... when I finished soldering I closed the box, used the amp for half an hour, and then shut it off.

after an hour or two I turned it on to show the GF, and it instantly started smelling funny, and smoking a bit ... opened the box, and the result is easy to spot on the pic ... [:'(]

Dan,

Oh no!!! Looks like you've got some cooked silicon there. You said that the amp was working with less noise for a while before you closed up the box? It sounds like something went wrong with your ground connection - can you send a pic of what it looks like now post-mortem?

Thanks,
Ian Williams

Also, what power supply voltage were you using?