I am the original owner of this DC300A. It drives some JBL cabinet speakers but doesn't get used much in the last 25 years... maybe playing an hour or two every year. :-(
Anyways, went to give it a run and one channel is distorted while the other is clean / clear. Tested the cabling to the speaker and did a swap test and the problem stayed with the channel. Check the cabling to the crown IC150 pre amp, along with a swap and the problem stayed with the same side.... so the amp channel channel appears to be the problem.
I don't know much / anything about audio amps other than basic electronics type level measurements, etc along with general setup.
Started taking it apart. Attached is the layout of the boards with the front panel removed and main control board "loosely mounted".
Because the one channel works and other is distorted, I started checking all the resistor / capacitors (resistance reading) and comparing across sides of the output boards. The only significant difference that I could find was a resistance difference on a capacitor across the output terminals. On the good side, it reads resistively as 2.96k while on the bad side, it reads 3.97k. Its a .1 MF 200v Filmatic ITW. I don't have an ESR meter, just a regular DVM.
I know that a resistance measurement of capacitor doesn't have much meaning / use but is that difference enough to indicate a bad cap. In "amp land", I don't even know what the purpose of the cap is going across the output terminals.... getting rid of high frequency noise?
Any guidance on this thing would be greatly appreciated as I would love to get it working again as it deserves a better fate.
Anyways, went to give it a run and one channel is distorted while the other is clean / clear. Tested the cabling to the speaker and did a swap test and the problem stayed with the channel. Check the cabling to the crown IC150 pre amp, along with a swap and the problem stayed with the same side.... so the amp channel channel appears to be the problem.
I don't know much / anything about audio amps other than basic electronics type level measurements, etc along with general setup.
Started taking it apart. Attached is the layout of the boards with the front panel removed and main control board "loosely mounted".
Because the one channel works and other is distorted, I started checking all the resistor / capacitors (resistance reading) and comparing across sides of the output boards. The only significant difference that I could find was a resistance difference on a capacitor across the output terminals. On the good side, it reads resistively as 2.96k while on the bad side, it reads 3.97k. Its a .1 MF 200v Filmatic ITW. I don't have an ESR meter, just a regular DVM.
I know that a resistance measurement of capacitor doesn't have much meaning / use but is that difference enough to indicate a bad cap. In "amp land", I don't even know what the purpose of the cap is going across the output terminals.... getting rid of high frequency noise?
Any guidance on this thing would be greatly appreciated as I would love to get it working again as it deserves a better fate.
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