Noise from Ground Zero GZPA1.5000SPL

[Bertje]

I have this class D poweramp for repair here.
When turn on with just a speaker connected, without RCA, I can here a lot of noise. From SMPS??

Everything else is working OK, delivers al lot of power.

Idle current is 3,5-4A

Output filters are OK.

http://www.magma-audio.nl/view.asp?ID=163

Any suggestions?


Rob.

 

[luka]

what noise? from where? inside of amp? from speaker?

 

[Bertje]

From the speaker, high frequenty noise. The SMPS itself is quiet and is working normal.
I measured at the primary side squarewaves with a little overshoot, I think it's normal.
Rob.

 

[luka]

Small sinewave on output is normal [this is how D amps works], few Vpp at some high freq., @ what amp works, say about 100kHz or so [output stage]...

You can check this before output inductor... you have two, since this amp is bridge already if i'm not mistaken...