PDX-1.1000 Problem

mikaelfred · 9th July 2008, 09:10 AM

Hi! I have a big problem! I'm pretty embarrased to say this but when I plugged my PDX amp i accidentaly reversed the ground and the battery wires. I was in a hurry and I didn't double check. All the 4 fuses got blown. My technician checked my amp and told me there was 2 MOSFET IRFB4227 that where blown. Every thing else seemed fine.
Could this be possible?
Or is my amp totally blown?(The amp still goes on but but the light flashes like it's giving an error code)

Can someone help me out!!
Thanks in advance

Corax · 9th July 2008, 10:09 AM

Well, with high power car amps the input current could be tremendous (i.e. >100A) and a diode for reverse voltage protection will be omitted because of the unwanted voltage drop and the overall decreased efficiency of the dc/dc converter. That diode would have a peak power dissipation of up to 70...80W (@100A, even with Schottky's, if you can get one with such a high amp rating).
I guess you're in luck that only 2 MOSFETs in the SMPS (S_witched M_ode P_ower S_upply) are blown and nothing more.

Perry Babin · 9th July 2008, 10:25 AM

The IRFB4227 would be more likely to be used as output transistors. It would be VERY difficult to blow the output transistors by reversing the B+ and ground connections. Are you sure it was damaged by the reverse connection?

The outputs may have been blown before you wired it up and the fuses protected the amp's power supply from the reverse polarity.

amc32 · 9th July 2008, 03:49 PM

Once again Perry Mason is on the case.

mikaelfred · 9th July 2008, 05:30 PM

The amp worked well before. I had a manifacture defect on a Type X Sub, so I sent my sub for repairs but then decided to plug 2 other subs.

shagone · 18th July 2008, 12:31 AM

what type of defect? electrical or cosmetic? if electrical it could have taken the amp outputs out with it as Perry stated.

mikaelfred · 18th July 2008, 09:16 PM

it's electrical. do i have the change all of the outputs? there's 8 of them in total and I've already ordered 2.

Perry Babin · 18th July 2008, 09:36 PM

If the failed output transistors were operating in parallel with other transistors, it's best to replace all of the transistors in the parallel group of transistors. If the outputs are in two groups of 4 and one transistor from each group of 4 failed, you should replace all 8.

mikaelfred · 1st August 2008, 07:00 AM

Just wanted to let u know it was the output that was blown and I replaced it. The amp works fine!!! Thanks for your help!

jol50 · 1st August 2008, 08:03 PM

Quote:

Originally posted by amc32
Once again Perry Mason is on the case.

Perry Mason; that was a good Ozzy tune I have not heard in a long time.

Thanks for the update on the amp. If you only replace part of the transistors and it works, it could have a weakness in the future and blow again.

9th July 2008, 09:10 AM	#1
mikaelfred diyAudio Member Join Date: Jul 2008	PDX-1.1000 Problem Hi! I have a big problem! I'm pretty embarrased to say this but when I plugged my PDX amp i accidentaly reversed the ground and the battery wires. I was in a hurry and I didn't double check. All the 4 fuses got blown. My technician checked my amp and told me there was 2 MOSFET IRFB4227 that where blown. Every thing else seemed fine. Could this be possible? Or is my amp totally blown?(The amp still goes on but but the light flashes like it's giving an error code) Can someone help me out!! Thanks in advance

9th July 2008, 10:25 AM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The IRFB4227 would be more likely to be used as output transistors. It would be VERY difficult to blow the output transistors by reversing the B+ and ground connections. Are you sure it was damaged by the reverse connection? The outputs may have been blown before you wired it up and the fuses protected the amp's power supply from the reverse polarity. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

18th July 2008, 09:36 PM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If the failed output transistors were operating in parallel with other transistors, it's best to replace all of the transistors in the parallel group of transistors. If the outputs are in two groups of 4 and one transistor from each group of 4 failed, you should replace all 8. __________________ 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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9th July 2008, 10:09 AM	#2
Corax diyAudio Member Join Date: Feb 2005 Location: south of lower saxon	Well, with high power car amps the input current could be tremendous (i.e. >100A) and a diode for reverse voltage protection will be omitted because of the unwanted voltage drop and the overall decreased efficiency of the dc/dc converter. That diode would have a peak power dissipation of up to 70...80W (@100A, even with Schottky's, if you can get one with such a high amp rating). I guess you're in luck that only 2 MOSFETs in the SMPS (S_witched M_ode P_ower S_upply) are blown and nothing more.

9th July 2008, 03:49 PM	#4
amc32 diyAudio Member Join Date: Mar 2008	Once again Perry Mason is on the case.

9th July 2008, 05:30 PM	#5
mikaelfred diyAudio Member Join Date: Jul 2008	The amp worked well before. I had a manifacture defect on a Type X Sub, so I sent my sub for repairs but then decided to plug 2 other subs.

18th July 2008, 12:31 AM	#6
shagone diyAudio Member Join Date: Apr 2007	what type of defect? electrical or cosmetic? if electrical it could have taken the amp outputs out with it as Perry stated.

18th July 2008, 09:16 PM	#7
mikaelfred diyAudio Member Join Date: Jul 2008	it's electrical. do i have the change all of the outputs? there's 8 of them in total and I've already ordered 2.

1st August 2008, 07:00 AM	#9
mikaelfred diyAudio Member Join Date: Jul 2008	Just wanted to let u know it was the output that was blown and I replaced it. The amp works fine!!! Thanks for your help!

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