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panhead
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« on: July 08, 2011, 09:25:26 am » |
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A friend gave me the chassis from an old Magnavox console radio. It resembles a picture I found on the net for a 1950's model 477P. I'd like to get it up and running if possible. Anybody know where I can find a schematic or know anything about this radio?
Thanks
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Panhead
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PRR
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« Reply #1 on: July 08, 2011, 01:21:24 pm » |
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There's over 500 models. No 477. Tube-types or chassis numbers might help. Gross description could help: mono? stereo? AM? AM/FM? Phono input? How many knobs?
Does it have a power transformer??
What happens when you plug it in? Out on the patio with a long cord!
If no disaster, clip-lead a voltmeter to the first big cap after the rectifier, stand back, plug-in, and see if you have voltage.
Go step-by-step. The power and audio stages are a lot like a Champ or Deluxe, except much more cramped and different tone-networks (and twice-up for stereo). (Actually, a Champ/Deluxe is a lot like an older high-end radio's audio section, plus an added gain-stage in front, all better-built than usual radio construction.)
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panhead
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« Reply #2 on: July 08, 2011, 01:34:21 pm » |
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I haven't had a chance to get a real good look at it yet. It's mono, AM/FM, with a 6V6 output tube. It has a 5Y3 rectifier. Phono input. It may require a field coil speaker - there seem to be four or five speaker wires, but I need to trace them to verify.
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Panhead
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panhead
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« Reply #3 on: July 08, 2011, 01:35:59 pm » |
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And yes, it has a power transformer.
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Panhead
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PRR
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« Reply #4 on: July 09, 2011, 09:15:55 pm » |
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Do you want to get it up as a radio? Or as an amplifier?
As an amp: flame-test, look for reasonable (Champ-like) voltages on 6V6 and the triode next to it. Feed iPod across volume pot ends, it should play. For guitar, re-purpose the IF tube (between square cans) or the FM RF stage as an audio preamp.
Field-coil is unlikely by the 1950s. Odd-lots of excess speakers as "tweeters" were hip, and the crosover might be in the chassis.
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panhead
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« Reply #5 on: July 11, 2011, 11:53:41 am » |
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I had a chance to look more closely at the radio over the weekend. It actually has two 6V6's, so I'm assuming now that it's push-pull. There's an octal socket for the speaker, with pin 3 from both 6V6's landing on it. There is no OT, so I'm assuming that was mounted on the speaker and plugs into the octal socket. The chassis is stamped Dec 2 1949. At this point I'll probably cannabalize it for useable parts, although I don't have much use for IF transformers or the tuning cap. Some of the coupling caps might be okay, but I have doubts about the electrolytics, since I don't know when the last time this thing was fired up was. Maybe the 6V6's and 5Y3 are okay. Oh well, it looked like it might have been a fun project. Who knows, maybe I'll mount an OT on a speaker and try it out based on the "long extension cord to the patio" method you outlined. Anyway, thanks for the input.
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Panhead
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PRR
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« Reply #6 on: July 12, 2011, 01:29:59 am » |
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> two 6V6's... Dec 2 1949
6SK7 6SA7 6SK7 6J5 6J6 6SN7GT 6V6GT 6V6GT 5Y3GT laid-out as shown in the attach below?
Chassis CR-199.
> There's an octal socket for the speaker
Betcha it has 7 holes, not 8/Octal. (And this plus 1949 does lean to Field-Coil.)
> cannabalize it for useable parts
It will need work, but I _DO_NOT_ think stripping it profits anyone.
It is a sturdy chassis. Lots of knob-holes. The audio section is probably very mellow yet musical: the old radio-sellers knew their art, and this is a top-line model.
It even has an "EXT" input!! No dorking-around disconnecting the tuner. And a 6J5 only used as a diode, ready to be your preamp. And some head-scratching tone networks.
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