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Magnovox Phono Console

Beatnik said:
It's been enjoyable cleaning it up, tomorrow hopefully Frys will have some caps after I get a list together. Picked up these aluminum knobs on sale at RS for 2.79 a pair.
Click to expand...

Your best bet is someplace like Antique Electronic Supply. A (near) perfect power supply cap would be this:

https://www.tubesandmore.com/products/C-EC4030X2-450

And for replacing the two 0.01uF coupling caps you do a lot worse than either 0.01uF or 0.022uF / 600V Sprague 716P:

https://www.tubesandmore.com/products/C-P-600V

Not trying to drum up business, but if you are going to be mucking about in there, you might as well do it right. :thmbsp:

Oh, and here's the original schematic:

http://www.audiokarma.org/forums/attachment.php?attachmentid=317452&d=1323939079

And a related modified (e.g. no tone controls) schematic:

http://www.audiokarma.org/forums/attachment.php?attachmentid=254756&d=1297210272

Best of luck!

-D
 
I going to wait until I do some soldering to fire it up, no pun.

It has a pilot light terminal, could I just hook up there for that ?
 
Beatnik said:
It's been enjoyable cleaning it up, tomorrow hopefully Frys will have some caps after I get a list together. Picked up these aluminum knobs on sale at RS for 2.79 a pair.
Click to expand...

I liked the old knobs just fine, but those are nice, too. Fry's doesn't always have everything you'll need. You might have to run to Tanner in Carrollton.



Beatnik said:
...It has a pilot light terminal, could I just hook up there for that ?
Click to expand...

Yes. I hooked up to the pilot light wires on my Magnavox 175's and used a $3 LED with silver mount from Radio Shack and a 110 ohm resistor, if I recall. You can see that build here:

http://www.audiokarma.org/forums/showthread.php?t=617499&highlight=magnavox
 
Thanks for the compliment, I have quite a stock pile of oak. I was going to just make a quick faceplate, but decided I wanted the chassis raised a bit so it lifts it up 1/4". Meant I had to do something in the back. Neither is fixed to it yet, that will be next.

I grabbed a push switch at Lowes earlier that has a 3/8 shaft I though I could mount through a spare hole in the back, can't get passed the transformer with it !

I'm going to look in build your thread now. I wonder if Tanner is open Friday ?
 

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Okay, the canned caps are polarized, those two (coupling ?) Good All white caps polarized or non polarized ?

Basics:
How close do I need to get the numbers ?
What happens with series and or parallel voltages ?
 
So, if I pull out an amp and a 1/4" cable, touch the wires to sleeve and tip, listen for which way gives the least hum ? That means the foil is at the tip or sleeve when it hums less ? Does that side go where the Line is on the old cap ?
 
Outer foil to tip on the 1/4 plug will hum more if you grab it.

yes, the noisier side goes to the line on the original cap.
 
White caps are 0.1 uF, and I think they should just be removed. They're used to EQ the overall system (phono, tone controls, amp, speakers) in the original unit. They increase feedback at midrange and up, effectively boosting bass. As a stand-alone, you want a flat response from the amp.
 
BTW - the treble control is "cut" only, bass control will have no effect all unless you're driving it with a ceramic cartridge.

Oh yeah - and loudness compensation is hard wired to volume control.
 
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Maybe I should just sell it.

Looking at the schematic, the only .1 mfd caps C7 and C10 show to be polarized ?

28.gif
 
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Those symbols are used interchangably, especially in the old days. Polarized caps will have a + or a - marking on the symbol too. If you look at the power supply section, you'll see that.


If those are used for some sort of tone compensation, then you may be able to leave them out. The schematic linked earlier didn't include the tone controls, so I thought the 0.1uf caps were the coupling caps. I'll shut up now for lack of the right schematic info :) I've never had this particular amp, so I have no direct experience with it's workings.
 
So far I've found two different schematics labeled 8301-10.
 

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Ordered caps from wjoe.com

Needed
40mfd 350v
40mfd 350v
20mfd 300v
30mfd 25v
.1mfd 200v
.1mfd 200v

Ordered
40uf 450v
40uf 450v
20uf 450v
33uf 33v also 30uf 160v which would be better to use here ?
.1uf 400v
.1uf 400v

The schematic above shows c7 and c10 as 10000mmf ?
 
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