Hey Big Watts fans, I started this project a couple of days ago. Here's a size comparison, this guy is huge! It was 105 pounds all packed up. It is 25" wide by 19" deep by 7-1/2" tall. It will do 330 watts per channel.
The inside views, the 4 main filters were already replaced, the old ones had leaked out and did some corrosion damage. I'll likely add some "meat" to the fix already done.
The issue was smoke followed by no audio. Before I ever powered it up I checked all 12 output transistors. Brought it up via a DBT / variac combo and all seemed well for about 30 seconds then the bulb went full bright and a wisp of smoke appeared. It led me to the source which was on the pre-driver amp board. There are two traces burned open and a good sized burn spot.
I dug out the burned board section and checked all the semi's on the board, all were well. I replaced the only two caps on this board and the other channel's as well. I ended up cutting the traces all the way back to the pads and running insulated wire, tacked down with epoxy. I also replaced two other caps for each channel on the driver/output boards. They are very swollen and one lead was corroded out.
This time the DBT power up was sucessful. With much bravery I started it up and the front panel lit up and I got that satisfying "click". After checking the DC level of the output terminals I plugged in some headphones and got audio. Today I hooked up some test speakers and gave it a bit of a workout. There's a fair level of hum going on with both channels, probably some bad cap(s) in the power supply. It's on the pre-amp side for sure.
I had already washed the chassis two weeks ago when I first got it and now it's on to a total recap. Also it will get a detailed cleaning and some experimenting to see if the main lighting will convert to warm white LED. DeOxit treatment will be done as controls and switches are exposed during the recapping. There's 11 toggle handle switches on this model!
More to follow as work progresses.
The inside views, the 4 main filters were already replaced, the old ones had leaked out and did some corrosion damage. I'll likely add some "meat" to the fix already done.
The issue was smoke followed by no audio. Before I ever powered it up I checked all 12 output transistors. Brought it up via a DBT / variac combo and all seemed well for about 30 seconds then the bulb went full bright and a wisp of smoke appeared. It led me to the source which was on the pre-driver amp board. There are two traces burned open and a good sized burn spot.
I dug out the burned board section and checked all the semi's on the board, all were well. I replaced the only two caps on this board and the other channel's as well. I ended up cutting the traces all the way back to the pads and running insulated wire, tacked down with epoxy. I also replaced two other caps for each channel on the driver/output boards. They are very swollen and one lead was corroded out.
This time the DBT power up was sucessful. With much bravery I started it up and the front panel lit up and I got that satisfying "click". After checking the DC level of the output terminals I plugged in some headphones and got audio. Today I hooked up some test speakers and gave it a bit of a workout. There's a fair level of hum going on with both channels, probably some bad cap(s) in the power supply. It's on the pre-amp side for sure.
I had already washed the chassis two weeks ago when I first got it and now it's on to a total recap. Also it will get a detailed cleaning and some experimenting to see if the main lighting will convert to warm white LED. DeOxit treatment will be done as controls and switches are exposed during the recapping. There's 11 toggle handle switches on this model!
More to follow as work progresses.