PPIPC1400.2 Blown

mbates14 · 22nd January 2010, 04:07 PM

I have one of these that have a couple outputs blown, all 6 power mosfets blown and the 7915 is blown, and all 11 input filter caps are blown. possibly the SG3525 as well.....

What gets me, is why the 7915 is blown apart? what would cause this?

1moreamp · 22nd January 2010, 05:13 PM

These regulators are design internally to shutdown in the event of a short circuit or overload. The damage you speak of sounds more like a lightning strike.

The Sg 3525 might be ok, and the blown caps might be a symptom of when the power mosfets folded over on themselves. I have seen these issues before, along with fried outputs, and no or improper fusing of the amp. I.E. its been dawged by a previous owner.
The 15 volt rail would worry me a lot also, as this is the entire front end of the amp with all of its ICs being possibly damaged. Hopefully the regulator went open right away preventing full rail supply from hitting all those ICs up front.

Does this amp have the ceramic SIP channel driver cards in it? Beware of these having bad solder joints, and if you need one the best place to get one is out of another PPI amp. avoiding building your own replacements if possible.

I would do a partial rebuild on the supply by not installing all the power fets and caps, then repairing the 15 reg, and removing all bad outputs and then simple bench testing of the amp by powering it up with a well regulated and protected bench supply. This would at least tell you if the front end is burned and weather of not its wise to continue on sinking time into this project.

mbates14 · 22nd January 2010, 05:27 PM

Well i changed the outputs, power transistors, and input caps with the 7915 and it appears to be working fine, so i guess it just decided to go when the rest of it did,

1moreamp · 22nd January 2010, 09:02 PM

Cool ! your on top of your game with this one...

22nd January 2010, 04:07 PM	#1
mbates14 diyAudio Member Join Date: Jun 2002 Location: non	PPIPC1400.2 Blown I have one of these that have a couple outputs blown, all 6 power mosfets blown and the 7915 is blown, and all 11 input filter caps are blown. possibly the SG3525 as well..... What gets me, is why the 7915 is blown apart? what would cause this?

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22nd January 2010, 05:13 PM	#2
1moreamp diyAudio Member Join Date: Dec 2005 Location: Northern California	These regulators are design internally to shutdown in the event of a short circuit or overload. The damage you speak of sounds more like a lightning strike. The Sg 3525 might be ok, and the blown caps might be a symptom of when the power mosfets folded over on themselves. I have seen these issues before, along with fried outputs, and no or improper fusing of the amp. I.E. its been dawged by a previous owner. The 15 volt rail would worry me a lot also, as this is the entire front end of the amp with all of its ICs being possibly damaged. Hopefully the regulator went open right away preventing full rail supply from hitting all those ICs up front. Does this amp have the ceramic SIP channel driver cards in it? Beware of these having bad solder joints, and if you need one the best place to get one is out of another PPI amp. avoiding building your own replacements if possible. I would do a partial rebuild on the supply by not installing all the power fets and caps, then repairing the 15 reg, and removing all bad outputs and then simple bench testing of the amp by powering it up with a well regulated and protected bench supply. This would at least tell you if the front end is burned and weather of not its wise to continue on sinking time into this project.

22nd January 2010, 05:27 PM	#3
mbates14 diyAudio Member Join Date: Jun 2002 Location: non	Well i changed the outputs, power transistors, and input caps with the 7915 and it appears to be working fine, so i guess it just decided to go when the rest of it did,

22nd January 2010, 09:02 PM	#4
1moreamp diyAudio Member Join Date: Dec 2005 Location: Northern California	Cool ! your on top of your game with this one...

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