Help? Alpine PDX 4.150 Dead of reverse polarity...

Itsme · 22nd October 2007, 10:46 AM

The other day my battery died and a dumb a** jumped me and reversed the connections on accident, Anyway he got me running but now my amp doesn't power up. Completely dead. So I thourghly disassembled amp and looked for any burnt or discolored componets. None found. I don't even smell anything burnt. I am only semi circuit knowledgeable, but this amp is a little differn't then I am used to. So if anybody can tell me what to check for I would greatly appreciate your knowledge! Thank you!

Randy Here are some pic's........

Pulse-R · 22nd October 2007, 10:58 AM

did you check the fuse/s?

often there's a large diode across the supply terminals which will cause the fuse to blow in reverse polarity. (although from looking at that pic, there isn't any diodes there)

better amps have an internal reverse-polarity sensing, and just do nothing if they're connected wrongly.

maybe also check the power and earth cables supplying the amp.
do you have 12v at the amp power cables?

a few more pics on this site:
http://www.realmofexcursion.com/ampg...ine_PDX-4.150/

the row of transistors across the top are the SMPS switchers - maybe check none of these have shorted legs

Itsme · 22nd October 2007, 04:34 PM

Yes I'm sorry, I forgot to mention both fuses are fine. I even tested continuity on fuses even though they were good visualy. Also yes 12.8 volts tested at inside power connectors. And it seems like the remote turn-on circuit is working. But power supply is dead. I am not getting voltage anywhere else in the circuit above 1 volt. It is a four layer PCB board and I cannot trace the 12+ circuit because it's inside the board? I think I have a picture of the protection diodes, But not sure if they are?

Itsme · 22nd October 2007, 04:35 PM

More pic's of my PDX 4.150

Itsme · 22nd October 2007, 04:36 PM

more pic's

Itsme · 22nd October 2007, 04:39 PM

Last pic is bottom of board and this pic is a close up of bottom and the Ice chipset.

Itsme · 22nd October 2007, 05:07 PM

This is the top of board. SMPS Switchers I think.

Itsme · 22nd October 2007, 05:09 PM

Anyway I am not sure what to test next? Any ideas would be appreciated. Thanks.

Perry Babin · 22nd October 2007, 05:17 PM

Measure the resistance from the B+ terminal to the center leg of the IRF3205. It should be ~0 ohms.

Measure the resistance from the third leg of the IRF3205 to the ground terminal. It should also read ~0 ohms.

Itsme · 22nd October 2007, 06:15 PM

I am Getting Infinity res. or open from B+ to IRF3205 all legs.
Is this good or bad?

22nd October 2007, 10:58 AM	#2
Pulse-R diyAudio Member Join Date: Mar 2005 Location: Melbourne	did you check the fuse/s? often there's a large diode across the supply terminals which will cause the fuse to blow in reverse polarity. (although from looking at that pic, there isn't any diodes there) better amps have an internal reverse-polarity sensing, and just do nothing if they're connected wrongly. maybe also check the power and earth cables supplying the amp. do you have 12v at the amp power cables? a few more pics on this site: http://www.realmofexcursion.com/ampg...ine_PDX-4.150/ the row of transistors across the top are the SMPS switchers - maybe check none of these have shorted legs __________________ Digital is only on or off

22nd October 2007, 05:17 PM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Measure the resistance from the B+ terminal to the center leg of the IRF3205. It should be ~0 ohms. Measure the resistance from the third leg of the IRF3205 to the ground terminal. It should also read ~0 ohms. __________________ 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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22nd October 2007, 05:09 PM	#8
Itsme diyAudio Member Join Date: Oct 2007	Anyway I am not sure what to test next? Any ideas would be appreciated. Thanks.

22nd October 2007, 06:15 PM	#10
Itsme diyAudio Member Join Date: Oct 2007	I am Getting Infinity res. or open from B+ to IRF3205 all legs. Is this good or bad?

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