I'm working on an active tube DI, based on the Altec 1566A:
I had to sub out the power transformer, but the new one is fairly close to the one called out in the schematic: It puts out 120VAC at 93 mA, and the filament is 6.3VAC at 1A. I'm inexperienced at best, but I did follow the schematic and the connections etc. are all good.
The filament side is fine, a little high at 6.8VDC but that seems at least in the ballpark. The problem is the B+; even bumping R9 up to 9500ohms, the lowest voltages I can get are 345VDC at "2" and 240VDC or so at "1."
In short: HELP!!!!!!!!!!!
I'm assuming I'm going to need to introduce a regulator of some kind; I have a spare LM350 but I need a plan!
-Seth
I had to sub out the power transformer, but the new one is fairly close to the one called out in the schematic: It puts out 120VAC at 93 mA, and the filament is 6.3VAC at 1A. I'm inexperienced at best, but I did follow the schematic and the connections etc. are all good.
The filament side is fine, a little high at 6.8VDC but that seems at least in the ballpark. The problem is the B+; even bumping R9 up to 9500ohms, the lowest voltages I can get are 345VDC at "2" and 240VDC or so at "1."
In short: HELP!!!!!!!!!!!
I'm assuming I'm going to need to introduce a regulator of some kind; I have a spare LM350 but I need a plan!
-Seth
Hmm...no. I suppose it couldn't hurt. But either way, something seems real off here. Supposedly:
2(146 * sqrt(2))= 412Vdc
which is actually just about what I got with the PT unloaded.
I'm just trying to figure out if this transformer is going to work at all or if there's a way to lose 25V or so right off the bat....
-Seth
2(146 * sqrt(2))= 412Vdc
which is actually just about what I got with the PT unloaded.
I'm just trying to figure out if this transformer is going to work at all or if there's a way to lose 25V or so right off the bat....
-Seth
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