What is the purpose of this capacitor?

[theguru21]

I need some help understanding why this capacitor is there...

Pay no attention to the scorch mark where R11 used to be, I'm in process of fixing that problem.

http://i65.photobucket.com/albums/h240/Moddage/DSC_0021.jpg


If you look at the image, you'll see a yellow cap across the 324. I found a low res picture of the guts of the same amp I have, (A Nakamichi PA-1004) and this capacitor doesn't exist on that one... Also the resistor to the right that's soldered to what appears to have been just a solid jumper doesn't exist on the PA-1004 amp I found a picture of.


Anyone know why my amp has a cap across the 324?


While we're on the subject of things like the 324, this amp has KEC brand chips in it, KIA324P and KIA494AP (as pictured). are these any good? or would I be better off replacing them with something better? if so, what should I look for? Just a standard TI replacement, or go higher end?


Thanks

~Aaron

 

[Perry Babin]

If it's soldered across pins 4 and 11, it's a bypass capacitor to help clean up the voltage feeding it. There may have been a problem causing the amp to malfunction under some conditions.

If they've worked for 10, 15, 20 years... you can' get much better than that. Time would show that they're reliable ICs.

There are no 'higher-end' parts. They either work or they don't.

 

[theguru21]

THANKS!

Thanks for the fast reply and knowledgable response!


As far as I know both IC's work correctly.


Going to order replacement parts for the failed transistors and get this thing back up.


Thanks,

~Aaron

 

[seankane]

Rockford had an update in alot of their bd mono amps with a jumper wire and a capacitor and it was to help eliminate turn on chatter while powering up.....or so thats what they say in their bulletin they released.

Not sure what IC your amp uses but Rockford used the SG3526.