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#1
04-07-2008, 07:22 PM
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b/w magnavox combo
picked up this b/w combo over the weekend . The owner said she bought it in 59 . However she claimed nothing worked anymore . Anyhow even though i have two other projects which i have not finished apart, i put them aside becuase i was a bit curious on this set . It definitly has a problem in amp section becuase the 6ca4 glows red hot. I only had it on a few seconds becuase i notice the tube red hot and a resister started to smoke . Turned it off instintly . Its all tube, the radio, tv, amp and tuner . However it looks to have a lot of miles on it . The black ring on yoke is falling apart, however i believe it can be repaired . The picture was replaced somewhere along the line with a 23fp4a , which has very low emissions after i checked it with my beltron . The tube layout chart says it was originally equipped with a 23mp4 . I have a few new old stock b/w tubes however none of them sub . Anyhow this really seems to be a basket case . I could not find any chassis number on it at all!!!. Just the model number 1mv387n . Usually the chassis number is needed to order a sams . Can anyone chime in and give me a clue on chassis number!!
Are the yoke and Picture tube available ??? Hate to toss it , its a nice set but it looks like a nightmare !!!! Would love to restore it . Any advise would be greatly appreciated . mike 
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#2
04-07-2008, 07:34 PM
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Looks as if another recapping job is in your immediate future. The 6CA4 is apparantly responding in rectifier duty to a shorted 'lytic somewhere down the line in the pi network it feeds--hence it's getting red with exertion, and a resistor down the line smoking with the same excessive current.
Seems as if this set has led a hard life if the kinescope is not original--and yet close to the edge in testing. You might be able to rejuve it. But it would seem that bringing this set back to life is going indeed to be a labor of love.... Other than that it would appear from the pics that you have a transformered, parallel-filamented chassis with 3--instead of the then often 2--picture IF stages. May be a set worth saving at that...
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#3
04-07-2008, 07:54 PM
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mag combo
well , i need a schematic however the label with chassis number is missing . Yes i figured the cap in amp section might be at fault . However there are two burnt resisters and i cant make out the values and i need a sams before i attempt to fool with this beast . Hopefully a crt is obtainable too . I like this one becuase its a small lightweight combo compared to others i have seen by magnavox . I have a few more pictures , any help indentifying the chassis would help . Any other suggestions are most appreciated .
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#4
04-07-2008, 10:46 PM
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What is a tube rectifier doing in a '59 B/W TV? I thought that by the mid 50's that the rects were going selenium?
-- Matt Davala
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#5
04-08-2008, 12:10 AM
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The audio amps in Magnavox consoles are well regarded in the tube audio world. Someone in the AK tube audio forum will probably recognize the likely model of audio amp you have, and may have schematics or know what those resistors should be.
As mentioned above, the filter caps in that amp probably have a short. And will need replacing. Quote:
This amp looks quite similar to yours. And the resistors look readable. Both 100 ohms If that doesn't load, see the bottom of the thread: http://www.diyaudio.com/forums/showthread/t-94209.html
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#7
04-08-2008, 05:31 PM
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I think all that those resistors are doing is being a voltage divider across the 6.3V heater supply. To fake a center-tap on the 6.3V power transformer winding. To make each leg of the heater supply look like 3.15V from chassis ground. It's a scheme to reduce hum from getting into the audio. I'd use bigger wattage resistors for replacements. But if you can measure with an ohmmeter 50 ohms from the chassis to one of the heater lines (when the power is off), then both resistors are good, and you need not worry about them.
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#8
04-09-2008, 09:51 AM
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maggy console
well i will check tonight and replace resisters if need, as well as replace caps and any defective tubes , then go from there . Have not found a chassis number on tv yet ??? . Kinda wanted a schematic before i got into that becuase in the event the yoke is not good , i will need a part number to go by if i have to obtain one .
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#9
04-09-2008, 12:00 PM
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If you do find that the TV is unfixable, be sure to save the audio amp, as these are highly regarded over in the tube audio AK forum.
As for that black plastic on the yoke, that by itself won't mean that the yoke is bad. Odds are that the yoke is good shape electrically, and will be quite fine as is.
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#10
04-09-2008, 02:17 PM
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well , i know the black plastic itself can be repaired and has no effect on the yoke , however the yoke itself is probably good , just a bit flimsy . I wanted to see if in the event it was , that if was was still available . Hate to put money into something that cant be finished . However i think the yoke will be ok . I like this set becuase its all tube and not a heavy bulky combo . I am starting the restoration .
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#11
04-14-2008, 07:00 AM
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well after getting into this amp , here is what i found . One of those 100 ohm resisters crumbled in my hand , so i replaced both of them with new 100 ohm resisters i had . Then i replaced the 4 section filter can with 4 individual capacitors . Had to mount two caps on top of chassis instead of underneath becuase i did have space . The 6ca4 tube is toasted, i checked it on my sencore tube tester . Probably becuase of the excess current it took. So unfortunatly after going through all my stuff i dont have that tube . Will be getting one on order . Also found the 6bq5 output tubes to be original , burnt and tested very weak . Replaced these two tubes with good used ones i had that tested well . SO far it seems to be coming along . I guess the next step might be to pull the radio out and go over that next . I also found the pilot lamps out which is normal , but these lamps are small round with two little pins sticking out of them , never seen ones like these before .
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#12
04-14-2008, 10:01 PM
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Those dial lamps with the two pins are probably #12's they are 6.3 volt at 150 ma.
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"proximo satis pro administratio" KAØSCR
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#14
04-16-2008, 07:19 AM
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"proximo satis pro administratio" KAØSCR
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