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TDA7293 isnt turning on Answered

I recently bought some TDA7293 chips figuring they'd make nice amplifiers, but when I tested one just now, nothing happens.  It doesn't even seem to take any power in, it doesn't heat, hum, smoke, pop, or anything else, and I've checked the wiring a bazillion times.  (12, actually, but that should be enough)  I'm using this circuit :  http://sound.westhost.com/project127.htm   on a +-12V supply, which is the minimum specs according to the datasheet.  I can't use a higher voltage because I don't have a higher voltage power supply right now (the 24V one I had hummed enough to destroy one of the other TDA7293s I had), and I want to remove all other possibilites before buying another split supply.  It has a little static when I take the power off, but leave the input connected, but it turns compleatley off if I apply voltage (but doesn't click or anything, there is no voltage going to the speaker at all.) 
Any ideas?

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steveastroukBest Answer (author)2013-03-25

Sure Mute and standby are tied high ? And its independent ground is grounded ?

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jduffy54 (author)steveastrouk2013-03-25

yes, and which pin is independent ground?

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jduffy54 (author)steveastrouk2013-03-25

Yes, it is, and did the format of instructables just change?
Also, I fixed the hum on my 24V supply (one of the caps was disconnected), but that didn't help.

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steveastrouk (author)jduffy542013-03-25

Yes. Weird when it happens isn't it ;-)

These amps are supposed to be bombproof, pretty well. Have you got good heatsinking ?

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jduffy54 (author)steveastrouk2013-03-25

No, but that's not an issue for two reasons
1) no heat was made. At all. The chip didn't pull ANY power.
2) I found out that that chip WAS fried, becasue I replaced it and it worked-for about two seconds because I forgot to turn the volume back down before powering up the new chip. I now have THREE broken chips, and no new ones left.
3) evidently not all that bombproof, as the last one DID run fine for about three seconds before it popped.

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steveastrouk (author)jduffy542013-03-26

....Which is why I ask about heatsinking. An amp that's blown by the load being on full volume makes me suspect the circuit is still wrong.

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jduffy54 (author)steveastrouk2013-03-26

it was run through a 10w amp first to a fairly low impedence load, and it doesn't matter now, because all my chips are dead.

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steveastrouk (author)jduffy542013-03-26

You've fried the input stage !

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jduffy54 (author)steveastrouk2013-03-26

yeah....I kinda noticed....

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steveastrouk (author)2013-03-25

I am assuming you are "applying" an AC signal, not DC ?

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jduffy54 (author)steveastrouk2013-03-25

The + and - to the amp are DC, but the input to the psu is AC, yes. There's no hum issue on the amp, the problem is that there is no sound or power used whatsoever.

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jduffy54 (author)jduffy542013-03-25

Correction to the question, I just noticed its not static when everthing is off, but some music is leaking through. Probably doesn't change anything though...

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jduffy54 (author)jduffy542013-03-25

I think I might have just fixed it. It would appear that it blew out while I wasn't looking, and just didn't pop or do anything else when powered. I replaced it, but forgot to turn down the volume so I may have just burned out my last chip...

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rickharris (author)jduffy542013-03-26

1. You need power

2. you need a good heat sink if your expecting any amount of output power

3. You need the right input level.Not too big and not too small.


4.Can you show a good photograph of what you have.

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jduffy54 (author)rickharris2013-03-26

1. Yes, i know that. I have power.
2. I wasn't worried about heatsinking until it had SOME kind of output. it had none.
3. Yes I noticed, I just forgot to switch back to a lower-powered source after switching to a new IC
4. Doesn't matter now, I just blew out my last chip.

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