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Chip Amps Amplifiers based on integrated circuits

LM3886 in a powered speaker
LM3886 in a powered speaker
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Old 15th May 2019, 09:50 AM   #1
Bruce@bluff is offline Bruce@bluff  South Africa
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Default LM3886 in a powered speaker

Greetings, I am repairing a powered speaker that has an tda7294 driving the compression driver and a TDA8954 on the low freq driver. They are fed from a common supply of app +-32v. The 7294 however has an offset of app 0.45v on the output which drops to few mv when an 8 ohm dummy load is connected when the dummy load is removed it goes back up to 0.45v again. I used a scope to check for oscillation. Is the chip faulty?
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Old 15th May 2019, 12:11 PM   #2
Bone is offline Bone  United Kingdom
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No
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Old 15th May 2019, 03:28 PM   #3
Mark Tillotson is offline Mark Tillotson
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Don't believe this is an issue - the output filter is ringing/clipping without a load, leading to artifacts like this, its not relevant to amp under load as the filter is then properly terminated.
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Old 15th May 2019, 07:12 PM   #4
anti is offline anti  Slovakia
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I too don't think that a TDA7294 in your "LM3886-powered speaker" is faulty.
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Old 16th May 2019, 05:48 AM   #5
Bruce@bluff is offline Bruce@bluff  South Africa
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Thanks for the reply's yes I know LM3386 should be TDA7294. I put a sinewave in it today and see what comes out
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Old 16th May 2019, 06:00 AM   #6
scottjoplin is offline scottjoplin  Wales
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The offset is high
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