Problem with LM4780

[Cyberzim]

Hello there!
Yesterday I did complete my PCB-board for a bridged LM4780.
Then I discovered a failure in my PCB. I had misunderstod how the mute-pin worked, and connected it to ground, so I removed the connection from those 2 pin, and soldered a 6K8 resistor to negative supply.
Today I have tested it, and it works, but there is a problem. When I turn it on, and play music, it doesn't play, but I have discovered, that it will work if I turn it on and off a few times.
Can it be wrong connection with the mute pin? and how many ohm should the resistor be at? I have a +/- 12.65 supply (25,3VDC).

[Cyberzim]

Okay, I can understand you can't help me without schematics, but I have used the schematics from the datasheets, and you can see my PCB-layout instead, but It's only singleside since I don't have acces to double layer.
LM4780 Bridged
Also I have experienced problems with oscillations and distortion in the higher freqencies, so I will apprechiate some help

Edit: The square vias on the pcb is jumpers, and they go verticals, and there are 4 jumpers.
And the pcb is also an edited one from my old, that had some mistakes

Regards,

Simon H.A.

[AndrewT]

Hi,
connect your speakers leads to just one output of the dual channel chip and hear if it is playing.
Then try the other channel to test it.

If both appear to work, then come back.

[Cyberzim]

They both work.

[AndrewT]

Originally posted by Cyberzim
When I turn it on, and play music, it doesn't play,

Originally posted by Cyberzim
They both work.

which?

[Cyberzim]

Well, they both work, but maybe it's some of the protection applications in the chip that sometimes turn it off. It's totally cool and I'm loading it with 8 ohm, so I don't think I'm overlimiting it, but do you think my pcb is good enough?
And sometimes it oscillate, can I do more to prevent it?

[AndrewT]

provide a link to the schematic you have used.

[Cyberzim]

I have used bridged application in the datasheets, but I can see I have missed some of the components, so I will put them on the board and etche a new board and try again.
Datasheets

Regards,

Simon H.A.

[bm0rg]

And sometimes it oscillate, can I do more to prevent it?

On page 18 of the cocument under LAYOUT, GROUND LOOPS AND STABILITY

consider using a star ground and have a look at the refrence board on page 22. I know its stereo but its a good refrence.

[pacificblue]

Originally posted by Cyberzim
Today I have tested it, and it works, but there is a problem. When I turn it on, and play music, it doesn't play, but I have discovered, that it will work if I turn it on and off a few times.
Can it be wrong connection with the mute pin? and how many ohm should the resistor be at? I have a +/- 12.65 supply (25,3VDC).

Could it be that your supply voltage is too low?
12,65 V sounds like a 9 V transformer times 1,41 without considering mains fluctuation, voltage drop across rectifier diodes and voltage sag under load. Voltage sag will be an issue, if all you have are 470 µF per rail.
Measure the actual supply voltage, when it works and when it does not work. The IC switches off, when the negative rail has less then 9 V to ground and less than 14 V to the positive rail.