Power Acoustik PS1-5500D

m4ick · 10th December 2011, 03:28 PM

This had a shorted output in each bank and a blown power supply.

I replaced the power supply fets and the output fets and it powers up and is oscillating and the oscillation at the inductors looks nice. The strange thing is that the high side gets considerably warmer than the low side.

I looked at the gates on the high side and all looks well but when I look at the gates on the low side the drive signal doesn't have a flat top, it's more of a saw tooth, shouldn't the drive be flat?

If so wouldn't that be a PNP driver not pulling it up quickly enough?

Perry Babin · 10th December 2011, 04:10 PM

Find the point where the two inductors connect (they're in series). Look at the square wave signal level there. Is it precisely 1/2 of the amplitude of the square wave on the output transistors (drain or source, depending on the output transistor probed)?

m4ick · 10th December 2011, 04:23 PM

Yes but with much heavier ringing on the top of the waveform than on the bottom.

Perry Babin · 10th December 2011, 05:37 PM

If you twist the inductors, does that reduce the ringing?

m4ick · 10th December 2011, 06:05 PM

With all the twisting and turning I can muster it doesn't seem to make a difference. I tried prying with the back end of a pen and that didn't make a difference either.

m4ick · 10th December 2011, 06:06 PM

Although, these inductors are glued to the board pretty well.

m4ick · 10th December 2011, 06:15 PM

The outputs don't get too hot to touch or anything but on any successful amp repair I have ever done all of the heat sink mounted components (except voltage regs) stay nice and cold for at least a minute or two before you can notice ANY kind of warmth.

Not to mention the low side bank right next to the high side stays cold to the touch while the high side begins to warm up considerably.

Perry Babin · 10th December 2011, 08:33 PM

Where did you buy the outputs from?

m4ick · 10th December 2011, 08:42 PM

Newark

Perry Babin · 10th December 2011, 09:03 PM

The high side drivers rarely fail.

This sounds like the type of problem that you have when you're using counterfeit outputs. Newark is a reputable distributor but I've received components that were not good from their sister company MCM.

Have you insulated the windings where they tend to short on the inductors to ensure that that was not causing any problems?

10th December 2011, 03:28 PM	#1
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	Power Acoustik PS1-5500D This had a shorted output in each bank and a blown power supply. I replaced the power supply fets and the output fets and it powers up and is oscillating and the oscillation at the inductors looks nice. The strange thing is that the high side gets considerably warmer than the low side. I looked at the gates on the high side and all looks well but when I look at the gates on the low side the drive signal doesn't have a flat top, it's more of a saw tooth, shouldn't the drive be flat? If so wouldn't that be a PNP driver not pulling it up quickly enough? __________________ Scope - DMM - 460W Computer PSU - Tutorial

10th December 2011, 04:10 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Find the point where the two inductors connect (they're in series). Look at the square wave signal level there. Is it precisely 1/2 of the amplitude of the square wave on the output transistors (drain or source, depending on the output transistor probed)? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

10th December 2011, 04:23 PM	#3
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	Yes but with much heavier ringing on the top of the waveform than on the bottom. __________________ Scope - DMM - 460W Computer PSU - Tutorial

10th December 2011, 05:37 PM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If you twist the inductors, does that reduce the ringing? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

10th December 2011, 06:05 PM	#5
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	With all the twisting and turning I can muster it doesn't seem to make a difference. I tried prying with the back end of a pen and that didn't make a difference either. __________________ Scope - DMM - 460W Computer PSU - Tutorial


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10th December 2011, 06:06 PM	#6
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	Although, these inductors are glued to the board pretty well. __________________ Scope - DMM - 460W Computer PSU - Tutorial

10th December 2011, 06:15 PM	#7
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	The outputs don't get too hot to touch or anything but on any successful amp repair I have ever done all of the heat sink mounted components (except voltage regs) stay nice and cold for at least a minute or two before you can notice ANY kind of warmth. Not to mention the low side bank right next to the high side stays cold to the touch while the high side begins to warm up considerably. __________________ Scope - DMM - 460W Computer PSU - Tutorial

10th December 2011, 08:33 PM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Where did you buy the outputs from? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

10th December 2011, 08:42 PM	#9
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	Newark __________________ Scope - DMM - 460W Computer PSU - Tutorial

10th December 2011, 09:03 PM	#10
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The high side drivers rarely fail. This sounds like the type of problem that you have when you're using counterfeit outputs. Newark is a reputable distributor but I've received components that were not good from their sister company MCM. Have you insulated the windings where they tend to short on the inductors to ensure that that was not causing any problems? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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