Author Topic: Magnavox Stereo Theater 1MR418M restoration  (Read 4889 times)

electra225

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Magnavox Stereo Theater 1MR418M restoration
« on: June 22, 2018, 10:07:45 PM »
1=Run 1
M=Stereo Theater
R=Total Remote Control
418=model 18 in the 400 series
M (suffix)=27" picture tube/CRT

What I know so far.  It has a 93-02-10 amplifier, 57-XX-XX tuner chassis, possibly a 57-16-XX, pending being able to see the number better, 71-00-00 MPX chassis, C36-20-11 TV chassis and an unknown model solid state remote control amplifier chassis.  Two 12" side-firing woofers and two front-firing 4X10 horns.  There are two tubes in the TV tuner, 9 tubes in the radio tuner, three tubes in the MPX adapter, 17 tubes in the TV chassis plus the CRT, and 7 tubes in the audio amplifier.  39 tubes if I have counted right.  It has a replacement "jug" (picture tube) and has at least one GE tube in the TV chassis and one of the 6EU7's in the amp is a Radio Shack tube.  The shield for the IF strip in the radio tuner is missing, so there has been work done on this thing sometime during the last 55 years or so.  This particular model is listed in the 1962 catalog.  The code on the MPX chassis is 424253.  Since there were not 53 weeks in 1962, could this code be for the 25th week of 1963?  This presents the first mystery.  My understanding is that there were no tube Stereo Theaters built in 1963, according to the 1963 catalog.  I need to figure out the code on the MPX adapter.  I have codes for the speakers, but those make no sense to me.  Perhaps someone else can help with that.  I'll post those later.  I haven't gotten codes off tubes yet.

This instrument is alleged to have a "nasty" hum in the output.  If it still hums, that shows the power transformer is good.  That is my first area of exploration. 

This is all preliminary.  This will be a fascinating journey.   :)
I'm great at multi-tasking.  I can listen, ignore, and forget all at the same time.

Bill

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #1 on: June 23, 2018, 06:24:55 AM »
The first step taken for "Rest of the Story".  I can't wait for Greg to start on his new baby so we can all learn what makes a Magnavox Stereo Theater tick!

Bill

Alfista

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #2 on: June 23, 2018, 08:40:04 AM »
So is this in your possession, Greg? Has your quest finally come to an end???

I feel like we should collectively open a bottle of champagne!

-Tim

danrclem

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #3 on: June 23, 2018, 09:11:42 AM »
On the speakers there should be a number starting with 232 which is the Magnavox EIA speaker code.  The following number would be the last number of the year it was made in and the following two digits would be the week it was made in.

http://www.recycledsound.net/8_Speaker_EIA_codes.pdf

electra225

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #4 on: June 23, 2018, 01:12:21 PM »
Tim, it is not actually in MY possession just yet.  Bill is babysitting.  The quest is officially over for a Stereo Theater.  Don't tell my wife, but the next thing is a little Imperial.  Model 1ST665.   :)

Danny, thanks for that information.   The numbers I have for the woofers are 581201 and for the horns 580059.  These might be part numbers.  I need to secure Sams documentation for this thing to help with this.  I'll print those speaker codes so I can refer to them.
I'm great at multi-tasking.  I can listen, ignore, and forget all at the same time.

electra225

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #5 on: June 23, 2018, 02:32:44 PM »
The speaker numbers I posted earlier are Magnavox part numbers.

There are some nice features on this instrument that I have not seen typically on Magnavox.  They have put usable antenna connections and external speaker connections mounted to the cabinet, instead of kluged onto the back cover.  We also have the biggest rat's nest of wiring I have ever seen, even on a Magnavox.  This certainly can't be the way is was done from the factory.  The two green wires from the phono cartridge to the tuner are wrapped around the power wires to the TV. 

If you notice in the top picture, the amplifier is powered off the TV chassis.  You can see the plug in the right hand side of the picture, toward the top of the TV chassis.  There is a circuit breaker for the TV and an interlock power cord.  There are so many wires I can't really tell, so it begs the question does the remote control work with the entire instrument or just the TV?  If it turns the TV power on and off, adjusts the volume ( done with controls on the tuner) and changes channels, why would it not also change channels on the radio?  I don't see extra wires going to the changer.
I'm great at multi-tasking.  I can listen, ignore, and forget all at the same time.

danrclem

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #6 on: June 23, 2018, 08:14:30 PM »
See if you can get Bill to look at the speakers again.  The ones that I have saw have more than one set of numbers.  The number that starts with 232 seems to usually be on the basket somewhere.  On the heavy steel on yours that wraps around the magnet it looks like a 32215 and if it has a number in front of it the wires are covering it. 

electra225

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #7 on: June 23, 2018, 08:41:48 PM »
That would make the speakers coded for the 15th week of 1962, which makes sense.  Bill was good enough to get those numbers to quell my over-exuberant curiosity.  He got some extremely good pictures, which have been a big help.  It is hard to take good pictures of numbers with all the dangling wires.   :)

Danny, I don't suppose you would have the EIA codes for tubes you could post, do you?  I have misplaced my chart.....  :-[
I'm great at multi-tasking.  I can listen, ignore, and forget all at the same time.

electra225

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #8 on: June 23, 2018, 09:46:41 PM »
I have another speaker code for the 12" speakers.  "137-215".  137 is the code for manufacturer C.T.S.  "215" stands for the 15th week of 1962.  Consistent with the "232' code you cited.  I don't know what "C.T.S." stands for, though.  Why would there be two manufacturers' codes on the same speaker?  The "137-215" is printed under the part number on the magnet of the speaker.
I'm great at multi-tasking.  I can listen, ignore, and forget all at the same time.

ed from Baltimore

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #9 on: June 24, 2018, 02:43:39 AM »
That photograph of the wiring harnesses between all those chassis somehow reminds me of a mid-70's car engine compartment with the rat's nest of vacuum lines and drive belts between the various added emission control gadgets with AC and cruise control tossed in for extra credit. FM multiplex, remote control, tuner subchassis………….I can't even imagine if that were a color set with convergence board

electra225

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #10 on: June 24, 2018, 06:20:29 AM »
You are referring to the under hood area of a 1983 Oldsmobile 98 with the 307 "Y" corporate V-8.  The only identifiable components that stuck out from the vacuum hose mess was the top of the air cleaner, the air conditioning compressor and the painted fenders.  The rest of the engine was buried with vacuum hoses.  Changing the valve covers, prone to leak and set the car on fire, was a nearly all-day job for a trained and experienced auto mechanic. 

Fortunately for Magnavox, by the time color TV was introduced to the Stereo Theater line, the stereo components were solid state.  That eliminated the multiple chassis and all the associated wiring.  I have worked with Magnavox enough that the wiring does not concern me anymore.  That particular wad of wiring is not designed to be quite that messy.  Methinks the mess is aftermarket.  Magnavox used heavy paper hangers that get torn up by servicing and deteriorate from old age and let the wring fall into the bottom of the cabinet.  In this case, they did not fall onto the hot tubes in the amplifier.  The wiring is typically found with a sticky substance on it that has attracted dirt.  Each wire has to be cleaned with lacquer thinner and then tied up so it does not look so messy.  My intention is to gut the cabinet and have every part of this instrument in my hands at one point. 

"Gloriously Complicated".  That is the theme of my project.  With advancing age and decreasing eyesight and dexterity in my hands, this project will be a grand adventure.  Most people take these things apart, here I am restoring one. 
I'm great at multi-tasking.  I can listen, ignore, and forget all at the same time.

walyfd

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #11 on: June 24, 2018, 06:59:21 AM »
Congratulations on finally finding a viable candidate.  I must say I will miss the thread in the "Wanted" section.

This looks like it'll be a huge challenge...  looking forward to following your progress on it!

electra225

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #12 on: June 24, 2018, 07:52:05 AM »
I figured we should move the restoration discussion from the "Wanted" section out of respect for moderators and forum integrity.  Larry could move it or I could.   ;)

Thanks for your interest.  I hope we can have some fun with this and maybe I can learn something along the way.  I've wanted one of these for a long time and the search has gotten discouraging at times.  The guys on the old TV forum thought that finding one was impossible.  They were nearly right. 

I have been asked what the round doo-hickey under the picture tube is.  That is the Magnalux sensor.  Magnalux is a system that adjusts picture brightness to room lighting.  I don't know how it works yet.  We'll try to figure it out during the restoration.  The square thing in the picture tube mask is the sensor for the remote control system.
I'm great at multi-tasking.  I can listen, ignore, and forget all at the same time.

danrclem

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #13 on: June 24, 2018, 09:08:00 AM »
Here's a link with a lot of EIA codes.

http://triodeel.com/eiacode.htm

Don't put too much (if any) stock in the numbers that I mentioned.  The 137215 is probably what I thought was ?32215.  I couldn't see the first number and the 7 is probably what I thought was a 2.  The numbers in the picture are fuzzy and that's just what I thought they looked like.  Come to think maybe it's my eyes that see fuzzy.   ;D   

CTS stands for Chicago Telephone Supply.  I've seen that code before but don't remember what they were in.

You'll have that Stereo Theatre all figured out way before you pick it up and you'll be able to restore it blindfolded.   ;)



TC Chris

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Re: Magnavox Stereo Theater 1MR418M restoration
« Reply #14 on: June 24, 2018, 10:30:48 AM »
There are so many wires I can't really tell, so it begs the question does the remote control work with the entire instrument or just the TV?  If it turns the TV power on and off, adjusts the volume ( done with controls on the tuner) and changes channels, why would it not also change channels on the radio?  I don't see extra wires going to the changer.

Remember that TV tuners use a series of fixed tuned circuits for each TV channel.  Click click click.  But there are more FM stations and sometimes we need to off-tune a little bit, so tuning for FM or AM is usually continuous.  It was different later with digital devices.  But remote tuning on the radio would have been a lot more difficult back then.

There are exceptions.  I have a ca. 1949 Crosley TV with continuous tuning, and had a huge Dumont once with the same.  And in the 1930s there was a rage for electric tuning (usually mechanical, with a motor drive) and later push-button tuning with buttons selecting tuned circuits.  But think what a rat's nest all that would create....

Chris Campbell