Ringing on gate signal - Page 2

brandes.cm · 23rd January 2012, 12:45 PM

I will replace those with the correct part and see what happens.

brandes.cm · 24th January 2012, 12:23 AM

That did it. What amazes me is the fact some of the solder joints were factory. So those diodes were replaced with resistors intentionally when manufactured. Maybe that is why the company went out of business. Diablo Audio Technologies, model Hellfire 2500.1 I heard these production model amps would burn up and my guess this is why.

It's to bad it is a nice amp.

brandes.cm · 19th April 2012, 03:09 AM

I'm back working on this, the output fails when driven hard. Only thing I notice is the noisy gate signal on the upper fets. Is this a product of the output filter?

Perry Babin · 19th April 2012, 07:27 AM

Does it look noisy in differential mode?

brandes.cm · 19th April 2012, 12:12 PM

Yes, scope set to add, channel 2 inverted. Here is a pic.

Perry Babin · 19th April 2012, 12:30 PM

That's definitely not right. Where does the signal become noisy?

input of opto
output of opto
base of driver transistors
emitter of driver transistors

brandes.cm · 19th April 2012, 01:02 PM

I see it on the +12V supply and the output of the opto.

Perry Babin · 19th April 2012, 01:21 PM

When you captured the last scope image, did you have one probe on the source leg and one on the gate leg?

By +12v do you mean the B+ 12v feeding the amp?

brandes.cm · 19th April 2012, 01:49 PM

If you reference the sinuslive a1500 schematic you sent me, the last measurement was from the drain to gate. The +12v I mentioned is the n_mos12 supply from a secondary winding of the transformer.

Perry Babin · 19th April 2012, 04:38 PM

If you look at the voltage across pins 5 and 8 of the opto-coupler in differential mode, is the DC noisy?

If so, check the capacitor connected across that supply.

19th April 2012, 03:09 AM	#13
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	I'm back working on this, the output fails when driven hard. Only thing I notice is the noisy gate signal on the upper fets. Is this a product of the output filter? __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator

19th April 2012, 07:27 AM	#14
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Does it look noisy in differential mode? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

19th April 2012, 12:12 PM	#15
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Yes, scope set to add, channel 2 inverted. Here is a pic. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator

19th April 2012, 12:30 PM	#16
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	That's definitely not right. Where does the signal become noisy? input of opto output of opto base of driver transistors emitter of driver transistors __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

19th April 2012, 01:02 PM	#17
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	I see it on the +12V supply and the output of the opto. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator


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23rd January 2012, 12:45 PM	#11
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	I will replace those with the correct part and see what happens.

24th January 2012, 12:23 AM	#12
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	That did it. What amazes me is the fact some of the solder joints were factory. So those diodes were replaced with resistors intentionally when manufactured. Maybe that is why the company went out of business. Diablo Audio Technologies, model Hellfire 2500.1 I heard these production model amps would burn up and my guess this is why. It's to bad it is a nice amp.

19th April 2012, 01:21 PM	#18
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	When you captured the last scope image, did you have one probe on the source leg and one on the gate leg? By +12v do you mean the B+ 12v feeding the amp? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

19th April 2012, 01:49 PM	#19
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	If you reference the sinuslive a1500 schematic you sent me, the last measurement was from the drain to gate. The +12v I mentioned is the n_mos12 supply from a secondary winding of the transformer. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator

19th April 2012, 04:38 PM	#20
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If you look at the voltage across pins 5 and 8 of the opto-coupler in differential mode, is the DC noisy? If so, check the capacitor connected across that supply. __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

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