# Precision Power A404



## Snajo (Dec 22, 2013)

I bought a PPI A404 from a forum member with advance knowledge that it wasn't fully operational.

There are two repair stickers on the inside bottom cover. One is 7/17/96 "Ted" and the other is 10/22/98 with cursive initials.

On the power supply side of the board three of the eight voltage regulators are visually destroyed. The long metal ground(?) bar is also detached at one end. I can't see what it was electrically attached to, so I may need to figure out how to safely remove the board from the case to repair it.

My goal is return it to normal operation.

Three and a half questions:
1. What does the ground bar physically connect to and do I need to remove the board from the case to repair it? How can I safely remove the board from the case?
2. Can anyone suggest a reliable place to purchase 8 quality pieces of RFP25NO5 (mosfets)? Answer: recommendations for these were found on a thread at Steve Meads.
3. What needs to be tested and possibly replaced in conjunction with the MOSFETs? Nothing else is visibly damaged. Answer: electrolytic caps and nearby resistors and diodes. Also learn how to test the two rectifiers/volt regulators.

Thanks. I'm going to research other threads of course, but this is where I am now.


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## vwdave (Jun 12, 2013)

So the board DOES need to come off for the repairs. I can't see what you are pointing at in regards to the ground. As for the FETs, when you replace them Id replace their respective resistor plus check all of the other resistors. 

While you are at it Id suggest replacing the PWM chip and putting in a socket as well so that it will be easy to change in future of it should event need to changed.


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## 1styearsi (Aug 13, 2012)

just saying when PPI called that art series they must have meant the board.
BEHOLD...THATS MADE IN THE USA IN ALL IT'S GLORY!!!!!


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## Snajo (Dec 22, 2013)

vwdave said:


> So the board DOES need to come off for the repairs. I can't see what you are pointing at in regards to the ground. As for the FETs, when you replace them Id replace their respective resistor plus check all of the other resistors.
> 
> While you are at it Id suggest replacing the PWM chip and putting in a socket as well so that it will be easy to change in future of it should event need to changed.


I wouldn't say the board has to come out. If I were only replacing a component or two, I'd probably leave it in. I expect its going to be more than that and with it out I'll be able to push the leads through the board and cut them after the components are soldered down. Easier to heat the leads up from the back... less stuff in the way.

Speaking of removing the board, it would've been a lot easier if someone hadn't glued the board to the case. I owe a photo of it later.


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## 1styearsi (Aug 13, 2012)

yes it does,to properly repair that you do need to remove the board,cleanup that 20+ year old heat sink compound and replace it that stuff is cheap.
taking the board out is not a big deal.
yo i don't mean to sound like a dick but if you are asking that question should not attempting the repair yourself.do yourself a favor and have it done by a pro....or not....


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## vwdave (Jun 12, 2013)

Yes I agree...nothin against you or anything but I hate buying amps from people that repaired them themselves by not removing the board. The bottom side is the solder side, so to properly remove the bad components you need to get to the back side, and of course put the legs through the holes and solder it up from the proper side. If you let the legs all he way through then you'll probably short it out on the heatsink.

That "glue" is thermal paste, and without it your amp will blow FETs left and right. pPi does go a bit overboard with it, but it is also extremely necessary.

I do agree, with the questions your are asking I don't recommend tackling this repair without learning a but more. It's not hard, but there are things to know before getting into it.


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## FartinInTheTub (May 25, 2010)

Message ppi collector. He's a member here who loves these amps.


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## Snajo (Dec 22, 2013)

I did some reading here and this probably isn't the best place for me. Call me a nerd, but I didn't care much for middle school either.

We'll see how it goes. I'm more interested in getting back into technical work than I am about the amp. I'm not going to go all Kurt Cobain on myself if I screw it up. That said, I have a lot of respect for the amp. Whoever designed this actually gave a damn about what they were doing. I have a lot to learn and don't expect to be repairing anything until this fall.

I took my time getting the board out because, like it or not, someone glued the damn thing to the case. I ended up using hot air to soften the adhesive and a plastic trim removal tool to separate it from the case.


From the way this thing is situated, it looks like someone soldered it down on one side and then held the other end down while they soldered that side... basically leaving it under pressure until the solder point gave out.


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## vwdave (Jun 12, 2013)

Wow, so it was not glued down. Were there screws holding it down too or did they discard those when they glued it? The more I look at the board I don't see any open holes for screws but I also don't see any screws other than the perimeter ones. Very strange.

As for the rail...you might have to remove it and bend it back into shape, it looks like it warped some how.

My recommendation is to practice on a cheap amp rather than a coveted art series amp. I do t collect those amps but I can respect them and the fact that they have a following. I see cheap broken amps on eBay all day long, in fact I just sold a pretty badass (but broken) fosgate amp for $25 to a lucky buyer.


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## Maverail (Jul 4, 2015)

"Three and a half questions"


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## wagonmaster (Jun 27, 2015)

So since the "shack" is closing where is a source for components.

Tim


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## vwdave (Jun 12, 2013)

Digikey.com, mouser.com, parts-express.com

Those are my two go-to places. I've got a few backups as well but try those places first. I NEVER use radio shack, at least not since the 80s it's just fun to go in there to mess with the sales people. I'm yet to find one that has ever plugged in a soldering iron.


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