PPI A600 amp blues...

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Hey I can't find much info on my PPI a600 amp. It's been a rock solid performer since new in '92. It's been running two bazooka 10's in stereo mode from an alpine eq it's whole life with no problems. Last week it popped the internal fuse. Upon replacement of the fuse the amp "squeals" for five seconds then pops the fuse. I found my main ground to chassis was loose. I fixed the ground, took the amp's cover off, powered it up and watched two fets get hot enough to smoke. Nothing is visually damaged or fried. However, now when I power it up nothing happens at all. Hope I didn't destroy it.

I want to fix this amp. It is truly an old school jewel. I will send it in but have no idea if it is fixable as well as where a good repair shop would be.

Thanks for your help. JK
 
Most of the older PPI amps use the bottom cover to clamp the power transistors to the heatsink. When the cover is removed, the thermal connection between the transistors and the sink is broken and the transistors will often overheat and fail if the amp is powered up.

It's likely that you had (have) a shorted output transistor. It sounds like the power supply transistors also failed since it was operated without the bottom cover.

Virtually any competent shop should be able to repair it. The only reason that it may not be repairable is if the driver board is physically damaged. As far as I know, they are no longer available.
 
I've had a couple, they are great amps. And like he said, you can't test them with the cover off... I learned that the hard way years ago:eek: when I had replaced every single output transistor and made the mistake of powering it up and using a speaker to test it. As far as I know there aren't any internal fuses in the art series amps.. unless you are talking about the 50 or 60 amp maxi fuse on the end. Shouldn't be too hard to fix, just might take several transistors to repair it. They aren't expensive though. Good luck
 
Wow thanks for the input.....If I didn't love this amp so much I'd just go buy a new one.

Yes it was the maxi fuse. I'm going to send it to a shop in Portland. (OR) The owner says he uses only original replacements but I wonder if originals are even available. I read in a few other posts about replacing all of the output and power supply transistors if any will be replaced at all.

Does that make sense?

Thanks again, JK
 
Everything is available to completely restore your PPI amp Except:

The Ceramic card drivers used by PPI in most of their amps of that era. The parts are no longer available even at PPI. I have several Original ones I used to reverse Engineer these cards. They are the entire front end of each channel up to the drivers and the outputs. PPI used these in many of there products and they are interchangeable.

They can be repaired in many circumstances, but in some situations replacement is the only way to bring the amp back to "like new" operation.

If it sounds like I know a lot about these parts, its because I do. As I have been repairing PPI amps ever since they opened their doors for business. And I was a PPI fan back then.

If you run into card troubles E-mail me and I will see what I can do to be of help. :)

The rest of the amp is pretty straight forward, there are several people here more then competent to get you taken care of, one of them is Perry. Your in good hands with his advice.
 
Just repaired one. Same problem. It's very common for transistors to short in amps. Well I guess out of what can go wrong that's pretty common. I just decided to replace everything on the edges. I tested the power supply and it checked fine. I replaced all the transistors and tested it on a Motorola service monitor. Its like new! Watch out for the thermal goo!

Corradolvr, CET
 
From what I can see there is no physical damage to the ceramic card drivers. So if there is a problem with one of these I will contact you. Thank you. My Corrado is just not the same without that PPI making it sound like I have John Paul Jones's bass rig in my back seat!!!
 
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