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Chip Amps Amplifiers based on integrated circuits

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Old 9th August 2011, 03:13 PM   #1
Havoxx is offline Havoxx  United States
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Default TDA7266

So I got three TDA 7266s from the sample order program, and I've tried to wire them according to the schematic, I'm using a 12v-0 power supply(wall wart) and I can't seem to get this thing to turn on, it's getting power to 3 and 13, and it gets power to the stby/mute pins as well.

I can't seem to figure out what could be wrong, it's like if it doesn't work at all, could it be that the chips were damaged or something? or am I missing something in the schematic? This is the schematic I used.
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Old 9th August 2011, 06:11 PM   #2
sregor is offline sregor  United States
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Quick question - do you have half the supply voltage at the outputs (1 + 2, and 14 + 15)? Does the heat sink get hot? Only other suggestion is to check carefully for solder bridges. Circuit is simple enough, it should work. Good luck.
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Old 9th August 2011, 06:30 PM   #3
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Hi there.
I've had a look at the datasheet here;

http://www.st.com/internet/com/TECHN...CD00000203.pdf

where you will find your circuit on page 5.

I would simply switch your circuit on and assuming any heat sink you have doesn't immediately start glowing, check your voltages as follows;

Pin
3, 13...................+12v
8, 9........................0v
1, 2, 14, 15............+6v (use some kind of load if not speakers, i.e. a 1k resistor).
4, 12.....................not sure but should be whatever Vref is. (couldn't find it in datasheet)
6, 7.......................starts at 0v and ramps to +6v in about 0.5 sec. (might be clamped internally, so perhaps won't reach +6v)

If these voltages are correct, then the amp should be running.

I would suggest that to measure 4, 12, you should short In1 and In2 to ground via a couple of 1k resistors, without any other input.

There's nothing fancy about this device, so if the voltages above are confirmed but you still get no output with an input signal applied then logically, the chip is faulty.

Sandy.

Last edited by mnemneth; 9th August 2011 at 06:38 PM.
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Old 9th August 2011, 08:30 PM   #4
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Hi there.
I've had a look at the datasheet here;

http://www.st.com/internet/com/TECHN...CD00000203.pdf

where you will find your circuit on page 5.

I would simply switch your circuit on and assuming any heat sink you have doesn't immediately start glowing, check your voltages as follows;

Pin
3, 13 +12v
8, 9 0v
1, 2, 14, 15 +6v
4, 12 not sure but should be whatever Vref is. (couldn't find it in datasheet)
6, 7 starts at 0v and ramps to +6v

If these voltages are correct, then the amp should be running.

I would suggest that to measure 4, 12, you should short In1 and In2 to ground via a couple of 1k resistors, without any other input.

Sandy.
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Old 10th August 2011, 04:39 AM   #5
Havoxx is offline Havoxx  United States
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Ok, thank you so much, I didn't really know how to test chips of this nature, I'm still learning as I go, as far as heat, no it's cold as ice, all 3 of them are.


Oh yea, stupid question, does an older PC power supply make a good chip amp supply? I do notice they have + - outputs, so I was curious about that.

Last edited by Havoxx; 10th August 2011 at 04:46 AM.
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Old 10th August 2011, 09:55 AM   #6
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Quote:
Originally Posted by Havoxx View Post
Ok, thank you so much, I didn't really know how to test chips of this nature, I'm still learning as I go, as far as heat, no it's cold as ice, all 3 of them are.


Oh yea, stupid question, does an older PC power supply make a good chip amp supply? I do notice they have + - outputs, so I was curious about that.
No questions are stupid! If you don't ask when you are unsure of something, then you will never learn.

The problem with old PC supplies is that they aren't designed for the job.

They have high current at +5v but only nominal 1A at +-12v, so you wouldn't get much power out.

PC supplies are also quite big, so not really suitable.

Best of luck with the amps.

Sandy.
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Old 10th August 2011, 02:36 PM   #7
Havoxx is offline Havoxx  United States
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I did have one other question about this chip, can I make it a 14w mono amp? I didn't see a recommended schematic in the list, so I was curious.

Also, how would I go about getting some of those reference boards in the datasheet made? do I just make them myself(try to anyway )

Last edited by Havoxx; 10th August 2011 at 02:49 PM.
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Old 10th August 2011, 04:27 PM   #8
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Quote:
Originally Posted by Havoxx View Post
I did have one other question about this chip, can I make it a 14w mono amp? I didn't see a recommended schematic in the list, so I was curious.

Also, how would I go about getting some of those reference boards in the datasheet made? do I just make them myself(try to anyway )
This chip is ALREADY a bridged amp, so basically no chance of doing what you're suggesting.

Have a look here;

Bridged and paralleled amplifiers - Wikipedia, the free encyclopedia

As to the PCB shown in the datasheet, I reckon you'll have to make it yourself. It's a pretty simple board, so should be easy.

Sandy.
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Old 11th August 2011, 01:27 AM   #9
Havoxx is offline Havoxx  United States
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Ah ok, so it's a bridged amplifier because the amps inside the IC are actually 4 amps that are bridged in a pair? thus making it a stereo bridged amp?
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