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69.71.1.1
In Reply to: RE: Magnavox 9302-00 Schematic posted by jec@afo.net on December 11, 2014 at 20:09:14
IMHO, you would be better off to power the Lafayette from the Magnavox power supply which is much better designed (slow turn-on tube rectified) via a 3-5 ft shielded cord and dispense with the Lafayette power supply. This would get inductive coupling and hum out of the picture. The connections on the Mag power supply transformer marked Y1 and Y2 is obviously to power a preamp (probably DC filaments) that is not shown on your Mag schematic. Most magnavox units had a seperate control box with volume, bass and treble controls (it probably had tubes). You will have to add a volume control to the input of the mag power amp if you don't have this preamp unit.M.B.
"...the fool doth think he is wise but the wise man knows himself to be nothing but a fool." Will Shakespeare
Follow Ups:
The 5U4 is directly heated and turns on almost as quickly as SS diodes do.
You are correct about being able to power additional equipment. IIRC the "extra" filament winding is 6.3 VAC for the tuner/preamp. Turning that into a proper DC filament supply for the phono preamp is easy.
Magnavox ran "117" VAC through the Molex connector in order to put the on/off switch in the tuner preamp. I strongly prefer keeping the AC mains line out of the umbilical between chassis.
For a console amp, this "puppy" is top of the line. The power trafo is "meaty". There is lots to work with.
Eli D.
I know I'm correct. We need to keep it simple for this beginner. M.B.
"...the fool doth think he is wise but the wise man knows himself to be nothing but a fool." Will Shakespeare
Measure the voltage at Y1 and Y2 either at the molex connector or at the power transformer of the Maggie. I bet it's 12.6v or 6.3v and ready to power a preamp. Also the maggie power supply is well designed and choke loaded and you can't do better for a power supply. All you would need to do is add another electrolytic cap at the end of the tri-cap filter and one voltage divider resistor to give you B+ for the Lafayette. M.B.
"...the fool doth think he is wise but the wise man knows himself to be nothing but a fool." Will Shakespeare
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