Noise from Ground Zero GZPA1.5000SPL

Bertje · 1st January 2009, 12:06 PM

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 · 1st January 2009, 12:25 PM

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

Bertje · 1st January 2009, 01:25 PM

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 · 2nd January 2009, 12:15 AM

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...

1st January 2009, 12:06 PM	#1
Bertje diyAudio Member Join Date: Jan 2004 Location: Holland	Noise from Ground Zero GZPA1.5000SPL 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.

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1st January 2009, 12:25 PM	#2
luka diyAudio Member Join Date: Sep 2005	what noise? from where? inside of amp? from speaker?

1st January 2009, 01:25 PM	#3
Bertje diyAudio Member Join Date: Jan 2004 Location: Holland	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.

2nd January 2009, 12:15 AM	#4
luka diyAudio Member Join Date: Sep 2005	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...

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