Hello all. I am new to posting here... I need some help with information on the little ceramic preamp board in the KAC-821 .. turns out when you clean this board with 99% isopropyl alcohol, it removes the resistor and tinned contacts and makes thing go poof... I have the service manual for this amp and I am able to translate where the preamp integrated with the rest of the amplifier. But am up to suggestions on building my own board for a successful repair.
Thanks for your time!
-Kevin
Thanks for your time!
-Kevin
Does the service manual actually give the schematic for that board? From what I saw, it's incomplete at best.
Isopropyl is not agressive and usualy causes no harm to components, it just cleans off the board.
Check what you are using!
Check what you are using!
It's a ceramic board with silver traces and carbon resistors 'painted' onto the board. With time, the silver oxidizes. Rockford and PPI had similar problems with their ceramic boards.
It is extremely incomplete when trying to repair this specific board. Though, looking at the op amps on the board I can say they are 8026D .. know how they are configured... "probably" a long lost design specific to Kenwood. But having a few tricks up my sleeve I potentially could create a board that can interface to the main circuits. Thus, not having the valuable knowledge of how these op amps work, I am lost and leads me to the question if it is even possible to create my own board with 2068d's?
Are you trying to restore the amp to original or are you simply trying to make it usable?
If you simply want it usable, you could bypass the board and use a ground loop isolator to provide the isolation that the preamp board was giving.
If you simply want it usable, you could bypass the board and use a ground loop isolator to provide the isolation that the preamp board was giving.
I would like to restore it- everything else works perfect on the board -nice solid square waves and caps seem to be within spec replaced a few leaky ones... probably some more will need to be replaced. With that, it seems like the perfect opportunity to learn something new and make a circuit board 😉