Hello all, I was hoping to get some input on the possibilities of fixing the amplifier in this subwoofer that is not powering on. If I can get it repaired I will likely make a separate cabinet for the amp so it’s no longer abused by the woofer.
There is a small AC board that has the AC in, fuse, power switch, and transformer on it. On the photo of the backside of the board youll see two jumpers I’ve put in, this is to simulate the power switch being in the on position. This board sends the full 120vac to the main amplifier board to be rectified. The 120vac is also passed onto the small transformer that is on that board which then sends AC voltage to the small input board that has all of the controls for gain, frequency cutoff, the power led, phase, etc.
I measure the 120vac going into the transformer, but I’m only measuring mV coming out. Somewhere around 15-16 mVac. So it seems the small transformer is toast. On the output side of the transformer there is a bridge rectifier made up of four 1N4001s and filter capacitance of a pair of 220uf caps. I replaced them so they are 35v rated and I can’t find the old ones. It’s likely they were rated for less. So 1 amp of current and fairly low voltage.
Does anyone have any clue on how I can possibly get this repaired? Any schematic with voltages present? Anyone possibly with on they’re using as a parts unit that I could buy the transformer from???? Any help would be greatly appreciated.
Dan
Edit: well nevermind on the photos. For whatever reason it isn’t letting me upload them.
There is a small AC board that has the AC in, fuse, power switch, and transformer on it. On the photo of the backside of the board youll see two jumpers I’ve put in, this is to simulate the power switch being in the on position. This board sends the full 120vac to the main amplifier board to be rectified. The 120vac is also passed onto the small transformer that is on that board which then sends AC voltage to the small input board that has all of the controls for gain, frequency cutoff, the power led, phase, etc.
I measure the 120vac going into the transformer, but I’m only measuring mV coming out. Somewhere around 15-16 mVac. So it seems the small transformer is toast. On the output side of the transformer there is a bridge rectifier made up of four 1N4001s and filter capacitance of a pair of 220uf caps. I replaced them so they are 35v rated and I can’t find the old ones. It’s likely they were rated for less. So 1 amp of current and fairly low voltage.
Does anyone have any clue on how I can possibly get this repaired? Any schematic with voltages present? Anyone possibly with on they’re using as a parts unit that I could buy the transformer from???? Any help would be greatly appreciated.
Dan
Edit: well nevermind on the photos. For whatever reason it isn’t letting me upload them.