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Old 26th November 2012, 12:07 AM   #1
lawdawg is offline lawdawg  United States
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Default 9302 Maggie Rebuild

Ok, picked up this console cheap and found this little gem inside. I rebuilt an 8802 with a lot of peoples help on this board, and am hoping for some more insight. I'm thinking this power transformer is toast, what do you think? Also the rectifier is burnt on two sides. Jim McShane.....do you sell PT's?
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Old 26th November 2012, 12:27 AM   #2
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If the power trafo is shot, as the leaking tar suggests, consider rebuilding as an "El Cheapo". Those undersized O/P trafos will probably work well in combination with triode wired "finals". Salvage the choke and buy the rest of the new power "iron" from Allied.

Jim McShane has all the parts needed to finish the job.
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Old 26th November 2012, 12:50 AM   #3
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Those amps were not fused, (unless you count the transfo windings as a fuse). As you observe the 5U4 may be shot too. It follows then that the can cap has probably shorted, failing the others. You probably want to replace it before installing a new transformer.

That transformer footprint is pretty common and you are likely to find another on an auction site. A couple years ago I found one NOS at a fair price.

How are the tubes?
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Old 26th November 2012, 11:31 AM   #4
lawdawg is offline lawdawg  United States
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Eli - you suggested "El Cheapo" on my 8802 also, and I know I'd be happy with the final product - but my electronics training was back in 1984 (& I don't even work in the field anymore). How close to "El Cheapo" is the 9302 stock?
Captn Dave - you're right, the rectifier looks shot.....as well as the right 6EU7 (gone to air). From what I've read, the 9302 should be a bit better on bass than the 8802 with my Klipsch Chorus II's
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Old 27th November 2012, 12:59 AM   #5
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I think upgrading the transformers and having a look at the coupling cap sizing for roll off would both help. I have one of those on the project pile awaiting the day I stumble across some nice transformers.
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Old 27th November 2012, 01:13 AM   #6
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The rectifier looks okay,to me. The big spots on the sides are the getter deposits. No way to know for sure without testing it.
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Old 27th November 2012, 01:46 AM   #7
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Quote:
How close to "El Cheapo" is the 9302 stock?
A stock Magnavox 9302 uses a paraphase splitter. "El Cheapo" uses a differential splitter. The circuits are quite different.

You are going to incur some costs, including power "iron", regardless of how the unit is made operable again. For quite good technical reasons, only "concertina" and differential phase splitters are currently "in vogue".

If you decide to go the "El Cheapo" route, install some sheet aluminum to fill in the cut out the failed OEM power trafo occupies. The "real estate" gained will be used for new power "iron" mounting. The chassis openings currently used for the rectifier tube socket and the can multi-section cap. will be used for new PSU capacitors. A new opening rates to be needed for the 2nd doubler stack cap., as the rectifier hole will take the 1st doubler stack part. I don't think it will be too much trouble to reuse the space the "Molex" power connector occupies as where the 7 pin mini socket the B- rectifier mounts.
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Old 28th November 2012, 02:17 AM   #8
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I had a really detailed long post to put up - and then somehow it went away as I was finishing the last sentence!! Grrr.. I'll try to reconstruct it and post it tomorrow.

But for now let me just say the El Cheapo idea is GREAT - and getting the existing power trafo rewound may be the best/easiest (albeit a bit more expensive) route to go.

More soon...
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Old 28th November 2012, 11:52 AM   #9
lawdawg is offline lawdawg  United States
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Thanks for all the info, El Cheapo is my desire- would require much help I'm afraid. @Jim - where could I get the PT rewound? Do you know of a place that does this?
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Old 28th November 2012, 03:47 PM   #10
20to20 is offline 20to20  United States
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Quote:
Originally Posted by lawdawg View Post
Thanks for all the info, El Cheapo is my desire- would require much help I'm afraid. @Jim - where could I get the PT rewound? Do you know of a place that does this?
LD,

I wouldn't write that tranny off as a gonner just yet. That tar is painted on the outside and that one looks like some kind of solvent or oil dripped onto it from above. Those consoles generally placed the turntable above the amp. Could have come from that or someone oiling a noisy platter, who knows?

Those trannys have the lead holes on the bottom. If anything was to "leak" from the tranny it would show there. Those leads also get some tar at the opening so that doesn't indicate a problem either. You really need to put a meter across the leads to look for a problem. Maybe find another rectifier and fire it up. Don't jump to conclusions from the looks of this one.

Good Luck.

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