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acebaker 9th August 2012 12:24 AM

power supply
 
PPI A-200. 4 1000uf 50v caps in the pwr supply. Are these caps "split" to work as 2 for each channel or not. One channel is out and when it went I could smell it. One cap has several little "bumps" around the side and what looks like a white crystalline substance (electrolyte?) on the bottom. The top is still intact. ( I watched one blow from the top before, looks like an oil well. Stinks too.) What do you stink? tanks

1moreamp 9th August 2012 02:34 AM

They are banked as 2 each 1000ufd caps per rail supply either positive or negative . PPI did not use dual mono designs and supplies in this series of amps. So your looking at one supply for all channels, which is fairly typical for the vast majority of the amps out there.

Only amps boasting dual mono designs usually have separate power supplies for each channel. Examples are Phoenix Gold MS-2125, MS-2250, MS-2500, MS-1000, ZPA 0.3, ZPA 0.5, MAC-500, etc... there are many others from back in the day, too many brand names to remember. Sony XM series and some of their other very high end gear from the early to late 90's. On and on, and I am sure there are a few even today...hope this helps...:)


The amp is old so unless you pull the caps and test them you can't really tell if they are bad. Barring leakage and such issues as PC Board damage from that leakage. A little piece of white thin cardboard slipped underneath them will show any electrolyte leakage upon removal after being swiped across the bottom underneath the cap while in place on the PC Board.
When I pull them I usually find they don't meet ufd spec in many cases. ESR is also a good test to tell but here again with all of that effort you could have just replaced them for a few dollars and been done with it. I suggest you use Panasonic FC grade replacements, I get mine from Mouser. They are exact drop in fit replacements but they are 105C rated and have a very good history of use in amps. Much better grade then the original 85C's

acebaker 14th August 2012 01:25 AM

caps
 
Thanks for that that 1more that is very helpfull. The board looks very clean so I'm going to pull all four caps and change them. But not until i get a new solder iron. I"ll take Perry's advice and get a good one.

1moreamp 14th August 2012 02:37 AM

That's good advice from Perry. Your gonna need good heat to get the large pad areas hot enough to release the original caps. There is another trick where you just wobble the large caps back and forth till you pull the lead legs right out of the caps, and then just use less heat to release the thru whole legs left standing. It might sound brutal but you were tossing the old caps anyway so no biggy about how you get them out...hope this helps some...:)

acebaker 14th August 2012 10:53 AM

caps
 
It does. I've got an old amp that I've been dis-membering slowly to practice on. I've done other repairs on other amps and had success but I sure wish My solderering was as pretty as the factory. I've been a gearhead most of my life and these "wrenching" hands are slow to adapt to fine work.


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