i need help for AMP CAR TDA1557

[kasimo]

Ok I built my TDA1557q amp and i using the design



*but

- i not have 270nf but i have Replacement i use 240nf

- and I do not put resistance 10k

- and Finally I do not use pin 12

*THE probleme is :

TDA1557Q IS WORK BUT I hear the voice of pure in the case if the sound is low but the performance is very low and when you lift the voice I hear a little voice very annoying and output power DC does not exceed 2 volts

*Note that the source of electricity or a car battery from 14 volts to 16.5 volts

[pacificblue]

Originally Posted by kasimo

- i not have 270nf but i have Replacement i use 240nf

- and I do not put resistance 10k

- and Finally I do not use pin 12

OK.

Originally Posted by kasimo

TDA1557Q IS WORK BUT I hear the voice of pure in the case if the sound is low but the performance is very low and when you lift the voice I hear a little voice very annoying and output power DC does not exceed 2 volts

Is this an automatic translation? If I get it correctly, you get clean sound at low volume, and you get annoying noise, when you raise the volume. Since you don't describe the sound, it is hard to help you.

Do you have a volume potentiometer with a metal case?
Connect the case to ground.
Connect the potentiometer ground with a separate wire to the amp. Don't daisy chain it, like a wire from the input to the pot, then to the amp.

Do you have a ground loop? Connect the source to the same grounding point as the amp with as short and thick a wire as possible.
Insert a small resistor of 10 Ohm or less, between signal ground (pin2 and input) and power ground (pins 5 and 6 and power supply).

Does the internal protection produce that noise? Check your heatsink temperature. Make sure the heatsink is big enough and thermal grease is applied.
Make sure your speaker impedance is 4 Ohm or higher.
Make sure that there is no short in the circuit.

Do you measure those 2 VDC between the speaker pins? That is too high and may cause the speaker protection to work.
Or do you measure those 2 VDC from speaker pin to ground? That is too low, and either the speaker protection is already working or the supply voltage is too low, the mute switch is not working correctly or there is a wiring mistake.

[kasimo]

Did not tell you for information to be good in the beginning but after 3 seconds after you turn the sound becomes annoying
In this case if the piece cool

[djoffe]

I'm guessing some, owing to lack of a good data sheet and the language issue, but...
1. perhaps the mute pin , pin 11 should be tied high...I can't tell if it has an internal pull-up from the abbreviated data sheet.
2. Do you have enough heat sink on the part? If it gets too warm, it will thermally shut down.

[kasimo]

thank you guys