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 Post subject: RCA Victor Special Model M Photo Tour
PostPosted: Aug Mon 11, 2014 1:19 am 
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The RCA Model M dates from about 1935 and is very rare, seldom seen outside of a museum. The cabinet was designed by industrial designer John Vassos, who also designed some console model radios for RCA. The mechanism was designed by Alfred Weiland and Seldon Williams.

The case is made of aluminum, the platform and other parts of aluminum, chromed steel and red velvet.

The motor mechanism is mechanical, wound by a crank. The amp is a three tube amplifier powered by batteries. It plays 78's only.

No, it's not mine. It belongs to an acquaintance and I'm doing some work on it for him.

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In the next post, I'll show the motor mechanism and amplifier.

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Aug Mon 11, 2014 1:28 am 
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The next sequence of photos show the underneath of the player:

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Aug Mon 11, 2014 1:42 am 
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Some time ago he sent me the amplifier, which I recapped, re-stuffing the original caps; and I checked the resistors and tubes. The tube line-up is 1H5, 1A5, and 1G6. I also made a set of batteries for him. I did not test the amp as I was reluctant to apply a load to it without the speaker and did not know what kind of speaker was used, but I suspected it might be a field coil type. The owner had the cartridge rebuilt. However, the audio is still not working.

So now I have the whole unit to check out. I haven't started troubleshooting yet, but I suspect the interstage (?) transformer may be bad as it looks as if it has gotten very hot.

One of the labels (see previous post) shows another transformer, which I assume is an audio output transformer, mounted on the speaker. The photos below were taken some time ago when he sent me the amp.

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Aug Mon 11, 2014 2:03 am 
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Ed, that is beautiful. I really love the tonearm and that flocked platter. These bring megabucks on eBay. Hope you can get it working good.


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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Aug Mon 11, 2014 8:21 am 
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Ed Morris wrote:
The RCA Model M dates from about 1935 and is very rare, seldom seen outside of a museum....


You know what is funny.....is I heard that statement repeated someplace before (maybe here) and a week later I saw one at the MARC show for sale. It was like $1,800 and everyone was asking is that $18.00 ?! LOL I have since seen several of these pop up at shows and folks usually asking a lot of money and no one even looking at 'em. Are they THAT rare? I have seen several at shows and yet to see one change hands.

They are kinda interesting but don't do much for me.

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Aug Wed 13, 2014 3:07 am 
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Thanx for the great photos. That design is pure genius. Absolute, machine age, streamline perfection. I never get tired of looking at that model. It's a metal sculpture masterpiece.
charlie (yes I'm Vassosian)

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Aug Wed 13, 2014 3:20 am 
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Love the red crinkle finish paint on the speaker cover.... that thing has HOT ROD written all over it!

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Aug Wed 13, 2014 9:30 pm 
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bastardbus wrote:
Ed Morris wrote:
The RCA Model M dates from about 1935 and is very rare, seldom seen outside of a museum....


You know what is funny.....is I heard that statement repeated someplace before (maybe here) and a week later I saw one at the MARC show for sale. It was like $1,800 and everyone was asking is that $18.00 ?! LOL I have since seen several of these pop up at shows and folks usually asking a lot of money and no one even looking at 'em. Are they THAT rare? I have seen several at shows and yet to see one change hands.

They are kinda interesting but don't do much for me.


I agree -- I don't think they're as rare as many people believe. (If they are, I must be very lucky, as I've come across quite a few.) I do think they're beautiful, though, and would certainly give more than $18.00 for one!

My RCA V205 has the exact same tone arm/pickup, and it's a 1941 model, so I don't think this dates back to 1935...more likely 1940 or 1941.


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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Sun 19, 2014 5:49 am 
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ED. Just wonderful. Thanks for the great pictures.
I have had one for years sitting on a shelf waiting to be repaired. It's a bit rough and the aluminum is faded and stained.
You have inspired me to now try and tackle it.
The cartridge on mine is missing. Any ideas as to what it is?.
Does anyone have a schematic?


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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Sun 19, 2014 6:36 pm 
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Chunny wrote:
ED. Just wonderful. Thanks for the great pictures.
I have had one for years sitting on a shelf waiting to be repaired. It's a bit rough and the aluminum is faded and stained.
You have inspired me to now try and tackle it.
The cartridge on mine is missing. Any ideas as to what it is?.
Does anyone have a schematic?


You can find the schematic at:

http://home.comcast.net/~morrised2006/r ... ModelM.pdf

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Sun 19, 2014 7:08 pm 
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Thanks, Brian. I had to make that schematic in order to figure how the input transformer was wired. I was then able to check out the transformer, which turned out to be good in spite of the melted wax.

I posted the schematic on my website for others to be use in the event anyone else tries to restore one of these amplifiers. I don't know if I got it exactly right, so if anyone sees any errors, let me know.

Thanks to experts here on the Antique Radio Forum, I was able get the amp working. The problem turned out to be a small internal battery, long dead, that provides a bias voltage to one of the tube grids. I replaced it with a resistor, and the amp works fine now.

Here is a link to a video on the amplifier restoration of the RCA Victor Special Model M:

http://youtu.be/ueI2bnVafbI?list=UUmOUeD4fGD6qA2HMI38UBPw

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Mon 20, 2014 3:34 am 
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Thank you ED for the schematic. Excellent work, I'd be lost without it. Thanks for the video too, very helpful, It is where I first saw your restoration. There's not much info on this player out there so your documentation has been a revelation.

A few questions:
1. Batteries. What batteries did you use?. Are they re-chargeable.
2. Cartridge/stylus- I suspect being a battery operated item it is a special cartridge just for this unit.

Thanks: Chunny


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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Mon 20, 2014 4:24 am 
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Hi, Chunny,

1. Batteries

The owner provided original battery boxes that I re-stuffed. The battery on the right in the photo below is the A battery. I placed four C Cells in parallel in a 2x2 holder which fit nicely in the box to provide the 1.5 volt A supply for the tube filaments.

The two boxes on the left are 45 volt batteries wired in series for the 90 volt B supply to the tube plates. Each box contains five 9 volt cells in series. I also made a battery for another collector with a RCA Victor Special Model K, which used a Burgess 6Ta60 AB battery with a Trans-Oceanic type connector.

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2. Cartridge

Below is a photo of the cartridge. The owner told me he had it rebuilt at West-Tech services. I guess it might be an Astatic crystal cartridge, but I don't know for sure, and I don't know the voltage. Maybe someone here will recognize it.

The owner provided a Pfanstiel BAS-S sappire needle for it, but I suppose it could also use steel needles, although they would probably be pretty hard on orthophonic 78's.

The amp is a three tube unit and the schematic link can be found at the link above. Since there is no rectifier tube, I think each tube is used in a stage of amplification.

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Mon 20, 2014 5:20 am 
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Here is an RCA cartridge chart I found on West Tech's website. The tone arm on the Model M looks like the one in Fig. 2, which uses the cartridge in Fig. 7 if I understand the chart.

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Tue 21, 2014 5:05 pm 
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Hello Ed,
Thanks for the battery and cartridge info.
Did you use rechargeable batteries?.


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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Tue 21, 2014 11:06 pm 
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I use alkalines. They last a long time, especially in the A supply. The rechargeable batteries don't put out the same voltage as alkalines, and therefore may not work as well in the old tube stuff, although I know there are guys here on the forum that do use the rechargeable batteries. If you have them available, you can try them and see if they work for you, especially since the voltages may not be so critical in an amplifier circuit as opposed to a circuit with RF stages.

Below is a photo of the 45 volt battery. The five 9-volts fit in a cardboard tray that slides into the original battery box.

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Fri 24, 2014 8:20 pm 
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I found a couple of errors in my schematic, so I have uploaded a new version. If you downloaded a copy, delete it and download the new version. You can find it at the same link as before. Here's the link again:

http://home.comcast.net/~morrised2006/radios/RCA_ModelM.pdf

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Sun 26, 2014 4:57 am 
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Thank you Ed for the update . Thanks for marking out the components, makes life so much easier.
Much appreciated.


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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Sun 26, 2014 5:05 am 
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Chunny, let me know if you find any errors or variances. I have noted small variances in capacitor values in the three that I have done.

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 Post subject: Re: RCA Victor Special Model M Photo Tour
PostPosted: Oct Sun 26, 2014 5:51 am 
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Hello Ed,
I'll keep you posted. Time permitting I am planning on starting the renovation within the next few weeks.
You mentioned you worked on a Model K. How did that vary?.
I also found a Model L that is again in a bit of a sad state but it all seems complete minus the batteries.


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