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Old 19th June 2005, 03:36 PM   #1
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Default Problem with TDA7262 + 30Vdc???

I built a small chip amp using a 20+20 watt ST brand TDA-7262 chip and if i use a 30VDC power supply, the amp works at low and medium volumes, but as you come close to clip, it makes this horrendus noise that sounds like a condenser mix being overdriven.

If i use a 12-14vdc power supply, i have no noise, and it sounds like its making close to the same amount of power and it clips easily and cleanly like any other amp with out any bad noises.

The spec sheet says 35vdc is max, so 30V at idle should be ok i would think.

I have not had time to do any formal testing to see what the problem may be as we were rushing to get a demo prototype out the door before a large trade show. I will do some more testing this week and see what i find.

But has anyone else used this chip, or had similar problems??

Zc
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Old 19th June 2005, 04:22 PM   #2
Netlist is offline Netlist  Belgium
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Default Re: Problem with TDA7262 + 30Vdc???

Quote:
Originally posted by Zero Cool
it sounds like its making close to the same amount of power
I have no experience with this chip but a dummy load and a 1kHz input signal would be the right tools to measure output voltage an current at different supply levels. Perhaps your problem will turn out to be rather normal in the end.

/Hugo
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Old 19th June 2005, 04:27 PM   #3
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Thanks, i did do some initial testing with a dummy load and saw no problems, but i was also using a very small 24V 500ma power supply as well as the larger units handt arrived yet and i was using anything i could find just for basic testing.

It was during our first listening test (with the correct Power supply) that we heard the noise.


Zc
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Old 19th June 2005, 04:33 PM   #4
Netlist is offline Netlist  Belgium
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Yes, 500mA is not even enough to start the engine. Perhaps enough for the idle current.
The scope will be your friend in this case.

/Hugo
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Old 20th June 2005, 05:59 AM   #5
Fossil is offline Fossil  Singapore
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500mA to share between 2 channels? that wld be too low!!
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