Sundown SAZ3500 -DC on output

brandes.cm · 28th February 2013, 02:42 AM

The amp has the sine wave riding on a negative 5V dc level. Does that sound like a leaky fet, I have pulled them and checked each one and found nothing out of the ordinary.

I have never run across this issue.

Perry Babin · 28th February 2013, 12:55 PM

Post a photo of the board (overall) and one of the driver board that they're using.

brandes.cm · 28th February 2013, 01:23 PM

They are using the dwm3640 with a piece of aluminum used as a heatsink. FQA24n50 output fets, 4 upper 4 lower per bank.

I wonder if a driver is messed up.

Perry Babin · 28th February 2013, 01:28 PM

Pin 9 on the driver board is+5v, 10 is input, 11 is ground, 12 is -5v. With the black probe on 11 and the red probe on 10, what is the DC voltage?

brandes.cm · 1st March 2013, 01:19 AM

pin 10 has -4VDC, hmm.

Perry Babin · 1st March 2013, 01:32 AM

Is there a 6.8k resistor feeding pin 10? If so, is the DC voltage on the driver board side of that resistor greater than the voltage (farther from 0v) on the other side of that resistor.

brandes.cm · 01:59 AM

Quote:

Originally Posted by Perry Babin

Is there a 6.8k resistor feeding pin 10? If so, is the DC voltage on the driver board side of that resistor greater than the voltage (farther from 0v) on the other side of that resistor.

Yes it ties to a 6.8K resistor. The voltage on the driver side seems more stable, if that makes any sense. If I try to apply a full 12VDC to B+ the amp starts to draw excessive current. I only have one output fet per bank populated.

<Edit>
I removed the output fets and now unable to reproduce the negative voltage on that pin.

Perry Babin · 1st March 2013, 09:27 PM

Was any work done to the amp previously or was the original problem -5v on the speaker terminals?

brandes.cm · 1st March 2013, 09:48 PM

That is how I received it. The output waveform riding on -5V.

Perry Babin · 1st March 2013, 10:58 PM

I would suspect the TL072 on the driver board.

28th February 2013, 02:42 AM	#1
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Sundown SAZ3500 -DC on output The amp has the sine wave riding on a negative 5V dc level. Does that sound like a leaky fet, I have pulled them and checked each one and found nothing out of the ordinary. I have never run across this issue. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator

28th February 2013, 12:55 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Post a photo of the board (overall) and one of the driver board that they're using. __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

28th February 2013, 01:23 PM	#3
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	They are using the dwm3640 with a piece of aluminum used as a heatsink. FQA24n50 output fets, 4 upper 4 lower per bank. I wonder if a driver is messed up. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator

28th February 2013, 01:28 PM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Pin 9 on the driver board is+5v, 10 is input, 11 is ground, 12 is -5v. With the black probe on 11 and the red probe on 10, what is the DC voltage? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

1st March 2013, 01:19 AM	#5
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	pin 10 has -4VDC, hmm. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator


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1st March 2013, 01:32 AM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Is there a 6.8k resistor feeding pin 10? If so, is the DC voltage on the driver board side of that resistor greater than the voltage (farther from 0v) on the other side of that resistor. __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

1st March 2013, 09:27 PM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Was any work done to the amp previously or was the original problem -5v on the speaker terminals? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

1st March 2013, 09:48 PM	#9
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	That is how I received it. The output waveform riding on -5V. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator

1st March 2013, 10:58 PM	#10
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	I would suspect the TL072 on the driver board. __________________ 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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