Sundown SAZ-1500 excessive current draw

brandes.cm · 29th July 2012, 03:10 PM

Originally the amp had failed supply and output fets. Supply is operational, output fets replaced, gate resistors verified. On power up amp with draw excessive current and it climbs with B+ voltage increase.

I can get the amp to stay out of protect by lifting D13 and using a current limit resistor. The outputs are IRF640N/IRF9640 pairs, essentially the AQ2200 schematic, same driver board with 4 transistors to drive the fets. The gate signal is roughly 40Khz on either rail. I only see a 5V square wave though, that seems to be my issue.

Thoughts,

IRF640N gate signal, gnd is two divisions above center.

timwebb · 29th July 2012, 03:31 PM

ive have those output drive transistors to fail very easy. ive have plenty that tested good but were defective.

brandes.cm · 29th July 2012, 05:00 PM

Note: 1)These amps do not like bringing the supply voltage up slowly, gets caught in some unknown region and causes excessive current.
2) The nomenclature on the board is wrong for the rca inputs, what says "out" is in.
3) Output section resembles AQ2200 and a host of Hifonics etc boards that use DWM1216 card.

timwebb · 29th July 2012, 05:25 PM

are the output fets in, in the second picture?

brandes.cm · 29th July 2012, 05:32 PM

Lifting D13 allows the amp to function, producing clean audio output. I need to hunt down the source of this protection issue.

brandes.cm · 29th July 2012, 08:24 PM

Anyone recognize this board, maybe have a schematic for another amp that is close.

Perry Babin · 30th July 2012, 12:35 AM

How much difference is there between the AQ2200 that you mentioned and this amp?

blazer40 · 30th July 2012, 12:40 AM

This reminds me of a hifonics hercules, but I think that the hercules has a diff driverboard and more outputs, but the rest looks the same. Are those irfp064's in the ps section? Does it run a ka7500 on the ps driverboard?

blazer40 · 30th July 2012, 12:45 AM

I had a sundown 3000d in here last week with protect issues, turned out to be the npn transistor hooked to pin 8 on the driverboard (but it's a bigger driverboard than your 1500).

brandes.cm · 30th July 2012, 01:06 AM

The AQ2200 uses a power supply driver board. I can't find why the protect trips right on power up. I lifted the inductors inline with the current sense for the outputs, still tripped.

Not sure where to start.

29th July 2012, 03:10 PM	#1
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Sundown SAZ-1500 excessive current draw Originally the amp had failed supply and output fets. Supply is operational, output fets replaced, gate resistors verified. On power up amp with draw excessive current and it climbs with B+ voltage increase. I can get the amp to stay out of protect by lifting D13 and using a current limit resistor. The outputs are IRF640N/IRF9640 pairs, essentially the AQ2200 schematic, same driver board with 4 transistors to drive the fets. The gate signal is roughly 40Khz on either rail. I only see a 5V square wave though, that seems to be my issue. Thoughts, IRF640N gate signal, gnd is two divisions above center. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator

29th July 2012, 05:00 PM	#3
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Note: 1)These amps do not like bringing the supply voltage up slowly, gets caught in some unknown region and causes excessive current. 2) The nomenclature on the board is wrong for the rca inputs, what says "out" is in. 3) Output section resembles AQ2200 and a host of Hifonics etc boards that use DWM1216 card. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator

29th July 2012, 05:32 PM	#5
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Lifting D13 allows the amp to function, producing clean audio output. I need to hunt down the source of this protection issue. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator

29th July 2012, 08:24 PM	#6
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Anyone recognize this board, maybe have a schematic for another amp that is close. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator

30th July 2012, 12:35 AM	#7
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	How much difference is there between the AQ2200 that you mentioned and this amp? __________________ 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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29th July 2012, 03:31 PM	#2
timwebb diyAudio Member Join Date: Jan 2010 Location: memphis tn	ive have those output drive transistors to fail very easy. ive have plenty that tested good but were defective.

29th July 2012, 05:25 PM	#4
timwebb diyAudio Member Join Date: Jan 2010 Location: memphis tn	are the output fets in, in the second picture?

30th July 2012, 12:40 AM	#8
blazer40 diyAudio Member Join Date: Oct 2010	This reminds me of a hifonics hercules, but I think that the hercules has a diff driverboard and more outputs, but the rest looks the same. Are those irfp064's in the ps section? Does it run a ka7500 on the ps driverboard?

30th July 2012, 12:45 AM	#9
blazer40 diyAudio Member Join Date: Oct 2010	I had a sundown 3000d in here last week with protect issues, turned out to be the npn transistor hooked to pin 8 on the driverboard (but it's a bigger driverboard than your 1500).

30th July 2012, 01:06 AM	#10
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	The AQ2200 uses a power supply driver board. I can't find why the protect trips right on power up. I lifted the inductors inline with the current sense for the outputs, still tripped. Not sure where to start. __________________ BK 1544 40Mhz scope.....Pyramid PS-26KX supply.....Tenma 72-380 Func. Generator

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