or
A funny thing happened on the way to a repair.
Thanks again to @nomadradio and @Dmans for reminding me of this.
For those of you that missed it ~
https://www.worldwidedx.com/threads/hygain-afterburner-plus-482-grid-bias.228873/
Usually it's because I just can't leave well enough alone. In this case my younger brother burned up the transformer trying to run 6LQ6's in place of the 6JU6's. As most know the weak point in all of these vintage amplifiers is the iron. Ironic then that now when they are found scavengers yard the tubes out and toss the chassis. When these were built the single most expensive part was the transformer.
So you would think that there should be half a zillion of these transformers just laying around. Nope.
You see the 6.3 isn't the issue it's the 800-1000V needed at the plate with enough current to make it go.
The next issue is finding a 325-0-325 with enough current to drive two tubes and still fit in the chassis without butchering the sheet metal or succumbing to the urge of an external power supply.
325-0-325 + 6.3 in the size needed just wasn't happening so I went to the last TV repair shop (around here anyway) and dug up a 350-0-350 that just might work. Enough resistance across the caps in the doubler and using the stouter 6MJ6 tubes it just might work.
The first step was to get the transformer in the chassis. Everything had to come out to stuff the new iron in.
The next three days were spent changing the position and location of the tank coil, moving the boards out to the edge of the chassis as far as they will go, and completing the the rest of the hook ups.
You'll notice there is no more room in the front of the box as the tubes have been moved forward.
There is so little room on the relay side that the relay is a near press fit to the cover.
The back of the tube sockets are so close to the chassis that several layers of insulation are needed.
Speaking of press fit, the cover is so tight over the top of the transformer that it takes a bit of patience to get it over the core and slid forward.
first Dave's 482
Now 20 pounds of krap in a 5 pound box
I haven't seen this thing with the cover off in 15 years. What a surprise when Major Void brought it over today. @Dmans , Dave, like you I biased it up and off just to try and keep the heat load off it. @nomadradio if you and Dave are looking for the filter caps, they're in there , near totally obscured by the transformer wiring that had to be turned 90 degrees just to make it all fit. Even then it wasn't that hard to hide the caps because anything more than 20MFD@500V ea in the filter and the diodes would die a sudden inrush current death. Not much of any place on that side of the box for a soft start so ...
I'll be bringing this big block sub compact back to life over the next few weeks. Stay tuned for the smoke show.
P.S. Thank You Cr and Dave . I had almost forgotten what it was like to do stupid shit in RF.
Void , Thank You for holding on to this piece of history.
Tater
A funny thing happened on the way to a repair.
Thanks again to @nomadradio and @Dmans for reminding me of this.
For those of you that missed it ~
https://www.worldwidedx.com/threads/hygain-afterburner-plus-482-grid-bias.228873/
Usually it's because I just can't leave well enough alone. In this case my younger brother burned up the transformer trying to run 6LQ6's in place of the 6JU6's. As most know the weak point in all of these vintage amplifiers is the iron. Ironic then that now when they are found scavengers yard the tubes out and toss the chassis. When these were built the single most expensive part was the transformer.
So you would think that there should be half a zillion of these transformers just laying around. Nope.
You see the 6.3 isn't the issue it's the 800-1000V needed at the plate with enough current to make it go.
The next issue is finding a 325-0-325 with enough current to drive two tubes and still fit in the chassis without butchering the sheet metal or succumbing to the urge of an external power supply.
325-0-325 + 6.3 in the size needed just wasn't happening so I went to the last TV repair shop (around here anyway) and dug up a 350-0-350 that just might work. Enough resistance across the caps in the doubler and using the stouter 6MJ6 tubes it just might work.
The first step was to get the transformer in the chassis. Everything had to come out to stuff the new iron in.
The next three days were spent changing the position and location of the tank coil, moving the boards out to the edge of the chassis as far as they will go, and completing the the rest of the hook ups.
You'll notice there is no more room in the front of the box as the tubes have been moved forward.
There is so little room on the relay side that the relay is a near press fit to the cover.
The back of the tube sockets are so close to the chassis that several layers of insulation are needed.
Speaking of press fit, the cover is so tight over the top of the transformer that it takes a bit of patience to get it over the core and slid forward.
first Dave's 482
Now 20 pounds of krap in a 5 pound box
I haven't seen this thing with the cover off in 15 years. What a surprise when Major Void brought it over today. @Dmans , Dave, like you I biased it up and off just to try and keep the heat load off it. @nomadradio if you and Dave are looking for the filter caps, they're in there , near totally obscured by the transformer wiring that had to be turned 90 degrees just to make it all fit. Even then it wasn't that hard to hide the caps because anything more than 20MFD@500V ea in the filter and the diodes would die a sudden inrush current death. Not much of any place on that side of the box for a soft start so ...
I'll be bringing this big block sub compact back to life over the next few weeks. Stay tuned for the smoke show.
P.S. Thank You Cr and Dave . I had almost forgotten what it was like to do stupid shit in RF.
Void , Thank You for holding on to this piece of history.
Tater
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