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George Wright AG1000 preamp power transformer spec

Hi all,
First off, sorry for the double posting. I also put this in the tube/DIY asylum, but a bunch of you guys hang out here....so wanted to make sure I covered all bases.

I have a George Wright AG1000 preamp on my bench from a customer. The power supply electrolytics have been replaced with good F and T axials of the exact same values as original design. I did this about a year ago. No other mods made. It ran for a few months and then blew a fuse. I put exactly the same component values as the original caps. The 6X4 is rated to have a 40 uF first filter cap and this one has a 22uF. I have determined there is a dead short in the 6.3V filament winding. This drives the 6X4 rectifier and a 6BM8 that is being used as a regulator. Of course there is no schematic and no specs on anything and unfortunately George Wright passed away. A web search is not turning up anything. There is no sign of any damage to any power supply component. The 120 ohm resistor off the 6X4 ahead of the first 22 uF filter cap reads exactly 120 ohms. Caps are all fine. It appears the transformer just decided to die. There is no sign of anything that could have killed it. All caps are less than a year old.

So the 6.3 V spec on the transformer is easy in that the combined 6X4 and 6BM8 filaments are 1.38 amps. So a 1.5 amp trafo is fine or a 2 A with a resistor or two to get the voltage back down to 6.3 VAC. The preamp has 3 x 6GU7 tubes and their filament supply is DC which is rectified off the only high voltage output of the power supply. The 6X4 is rated at 70 mA and has a 325 VAC max input to the plates. So I am trying to figure out what voltage secondary to use in a replacement. Does anyone have a schematic or transformer spec? Since the preamp is dead I have no idea what the B+ was.... Anyone have any leads?


Oh, and the resistance of the high voltage secondary is 2.6 ohms, but maybe it was damaged when the filament secondary died...hard to know for certain. Those are the clues....

Anyone with info on this unit please chime in..

thanks in advance,
Don

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Topic - George Wright AG1000 preamp power transformer spec - dls123 10:27:57 11/02/14 (6)
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