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amplifier cutt-working problem

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zesla

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Hi guys,

I have made an amplifier out of a LM3875 amplifier chip. The power supply is a DC 28x2 volts 4A adapter.

Now the problem is that when I increase the sound volume by the 10k pot of the amplifier the sound happens to cut off then starts working for a second then cut off gain...
I have no problem when the volume pot is low but as I told I get that problem when the volume pot is increased. It seems that after getting the cut off- then working repetitively after then by increasing he said pot the sound does not increase anymore just I got a very quick cut -then working!
The adapter caps are 6800uF and I have the said problem even before the chip or the heat sink gets warm.

Any idea what the problem can be? The circuit is made upon the Typical Application in the first page of the datasheet (you can see it below).

Thanks
 
Put a LED on the power supply and see if it flickers.

Thanks,

The circuit itself has an indicated LED and it does not flicks at all. I monitored the supply voltage for whens that the sound volume is low till it is at it's highest value, And the supply is constant.
 
How have you built it?, is there a recommended PCB in the datasheet, and have you followed that?.

You might try posting a picture of it here.


Regarding your first question I will look to see if there is any recommendation.

I am wondering what reason other than the power leakage (As I told in the above post my circuit does no have this problem) is able to cause an amplifier the work just fine when the sound pot is low but horrible when it is high?1
 
If needed, Here's the schematic:

When I increase the RIN (10k Pot I mean), I get the said problem.
 

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Thanks but actually NO, I am sure

Can you just use commonly recognised sentence-structure, so we can actually follow what you are saying.
English is a very accurate language and we can follow what you are saying if the words are assembled logically.
 
Can you just use commonly recognised sentence-structure, so we can actually follow what you are saying.
English is a very accurate language and we can follow what you are saying if the words are assembled logically.

lol, Sorry but I am just a beginner in English language.
I just meant I am sure that the Pot is not bad.
I just put the pot in the boundary situation And then replaced the RI by 500 ohm resistor, I had the said problem by doing so.
 
zesla,

Anyways back to fixing the problem, does the sound actually go in and out when your touching/moving the pot? If so the pot could just be dirty inside and need a bit of a clean up. If not, then something is being over-driven, or there is a leaky capacitor that is partially shorted, so allowing DC to flow along with the AC signal, making the sound distorted. The signal capacitors are supposed to only let the AC music sine wave pass, not dc from the amplifying circuits. If its a leaky capacitor its most likely a dried out electrolytic.

-Ben
 
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