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 Post subject: My New 1958 Motorola Imperial Masterpiece Console -Help?
PostPosted: Apr Tue 22, 2014 2:33 pm 
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Joined: Apr Tue 22, 2014 2:05 pm
Posts: 25
I wanted to share this beauty, and hopefully learn more about it from anyone who's familar with it. I drove 350 miles, pulling a trailer, from Lake Geneva, WI to Owosso, MI to pick this up over the Easter weekend. It was given to me by a family friend who is now in a nursing home (unfortunately). He has owned it since it was new in 1958! This is model #15KT25-B-1. The unit consists of a center console, which houses an HS-607 EL34-based mono amp, an HS-607 mono preamp and an HS-590 tube tuner. It also sports a Motorola badged V-M 1200 record changer. The speakers (2 of them!!!) are loaded with Electro-Voice components, specifically a 15" SP15 woofer, an 847 compound diffraction horn midrange and a T35 tweeter. The crossovers are EV X436. Each speaker also has separate tweeter and midrange "brilliance" controls. Each section of the console is 36"L x 30"H x 17"D, so the whole shebang is 9' long!

I have yet to power it up. From what I know, it works perfectly, but I'm afraid to just plug it in for fear of toasting something. Also, the power cord was completely shot and unsafe, so I cut it off. I want to recap it, but I'm looking for advice on which caps are essential to replace now to get it up and running. From what I gather, there are caps in all three components that should be replaced. I am attaching the schematics and parts lists for each, so if anyone is inclined to guide me on which one's should be replaced, I'd appreciate it. I would like to get the parts ordered so I can get started on this. I have never recapped tube electronics before, only speaker crossovers. But I would like to give it a try since there aren't many places to go locally (SE WI) to have it done. I have the photofact folder for the unit, which has all the schematics, photo layouts of components and parts lists. As for the changer, I just ordered the service manual from Gary at V-M Audio Enthusiasts, and plan to refurb it so it is in tip-top shape. I would like to put a stereo cartridge on it, so that I can play my stereo records (wired in mono, of course).

Any help, guidance, comments, etc. would be appreciated. I'm excited about the unit (probably more so than my wife is). I run a rebuilt Fisher 400 and Empire 398 and AR XA turntables in my listening room, so I'm a big fan of tubes and vintage equipment.

Thanks!

Tom


Attachments:
File comment: Center console (closed)
photo 11.JPG
photo 11.JPG [ 99.24 KiB | Viewed 2621 times ]
File comment: Center console (open)
photo 9.JPG
photo 9.JPG [ 93.57 KiB | Viewed 2621 times ]
File comment: Speaker cabinet
photo 13.JPG
photo 13.JPG [ 112.05 KiB | Viewed 2621 times ]
File comment: Record changer
photo 12.JPG
photo 12.JPG [ 98.86 KiB | Viewed 2621 times ]
File comment: Amp
photo 15.JPG
photo 15.JPG [ 97.68 KiB | Viewed 2621 times ]
File comment: Speaker components
photo 2.JPG
photo 2.JPG [ 113.64 KiB | Viewed 2621 times ]
File comment: Amp schematic and parts list
amp schematic.pdf [214.96 KiB]
Downloaded 80 times
File comment: Preamp schematic and parts list
preamp schematic.pdf [247.44 KiB]
Downloaded 61 times
File comment: Tuner schematic
tuner pic.pdf [135.43 KiB]
Downloaded 74 times
File comment: Tuner parts list
tuner parts list.pdf [133.7 KiB]
Downloaded 66 times
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 Post subject: Re: My New 1958 Motorola Imperial Masterpiece Console -Help?
PostPosted: Apr Tue 22, 2014 6:06 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4127
Location: Berkley, Michigan
Nice!

This set was Motorola's top of the line. I've never seen one in person but I sure would like to have one to play with. The sales literature I saw showed it using a Staar Galaxy record changer with a 4-pole motor but yours is a standard V-M changer as used in the standard Masterpiece console.

It's 56 years old. Anything over a half century old does not work "Perfectly", guaranteed. The good news is that Motorola liked to use ceramic capacitors so many of them may still be in good condition. The 6CA7 coupling capacitors are probably leaky though.

Very lucky find. It should shake the floor joists when it's running up to spec.

_________________
That warm tube sound can usually be overcome by turning up the treble.


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 Post subject: Re: My New 1958 Motorola Imperial Masterpiece Console -Help?
PostPosted: Apr Tue 22, 2014 6:37 pm 
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Joined: Apr Tue 22, 2014 2:05 pm
Posts: 25
Thanks, Doug. I see you're in Berkley ... My dad grew up there. I'm originally from Hamtramck and Detroit (grew up there in the '60's). Small world.

If you were restoring this, what would you replace? You mention the coupling capacitors (and I'm not sure which these are, so I'll have to figure that out). What else? I want to put an order together so I can get all the parts I need at one time. As I mentioned, this is a first for me, so I'm hoping to absorb as much as I can. I appreciate any and all advice, no matter how basic.

Tom


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 Post subject: Re: My New 1958 Motorola Imperial Masterpiece Console -Help?
PostPosted: Apr Tue 22, 2014 7:31 pm 
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Joined: Apr Wed 09, 2008 3:37 am
Posts: 14346
Location: Little Rock, Arkansas
Replace any wax capacitors under the amp with modern day 630-volt equivalents, and by all means replace all the electrolytic filter capacitors as well. That should get the amp up and running provided the resistors and tubes are good.


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 Post subject: Re: My New 1958 Motorola Imperial Masterpiece Console -Help?
PostPosted: Apr Tue 22, 2014 7:58 pm 
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Joined: Mar Tue 04, 2014 3:29 am
Posts: 2073
Location: Long Beach, CA 90808
EXCELLENT!

I love seeing these old beauties saved and restored and this one looks to be in incredible condition!

If you do as Larry and Doug have advised you should be blowing the roof off your listening room in no time!

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Aloha, Ken

No Console Left Behind!
Come join us @ http://vintagehifi.net/


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 Post subject: Re: My New 1958 Motorola Imperial Masterpiece Console -Help?
PostPosted: Apr Tue 22, 2014 8:30 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4127
Location: Berkley, Michigan
This set doesn't have any wax capacitors, it has ceramic jacketed tubular capacitors that also get leaky. For example on the power amp chassis, C-46 and C-47 are the audio coupling capacitors for the 6CA7 output tubes. If these become electrically leaky they cause the output tubes to draw a tremendous amount of current that can cause quite a bit of damage up to and including burning out the power transformer.

On the parts lists look for any of the 400 volt capacitors. It looks like there are 6 of them in the pre amp, 3 of them in the power amp and a number of them in the tuner as well. They may be different physical sizes but they will all look the same. Like Larry says, replace them with modern 630-volt replacements of the same value.

C-43, the 4-section electrolytic capacitor on the power amp chassis may still be good but you really can't trust it. It's a big job to replace this capacitor with 4 separate capacitors. The capacitor terminals are used as tie points and mounts for other leads and components. It requires a new terminal strip to move all of the leads and components from the old capacitor.

I usually power up the amp after I have replaced the output coupling capacitors and if there is no hum with the volume control at minimum, the DC supply voltages age good and the capacitor can remains cool I may let it slide for a while.

_________________
That warm tube sound can usually be overcome by turning up the treble.


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 Post subject: Re: My New 1958 Motorola Imperial Masterpiece Console -Help?
PostPosted: Apr Tue 22, 2014 8:52 pm 
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Joined: Apr Tue 22, 2014 2:05 pm
Posts: 25
Great!! I really appreciate the specifics on which components to replace. Now I can go through the parts lists and figure out exactly what I need to order. Where do you guys typically order your parts from?


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 Post subject: It's Alive!
PostPosted: Apr Mon 28, 2014 1:30 am 
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Joined: Apr Tue 22, 2014 2:05 pm
Posts: 25
:D :D
Thanks to the selfless advice and guidance of Pat, who I met on AK and who happens to also live in SE WI, I got the amp, preamp and tuner recapped (first recap ever for me), and believe it or not, IT WORKS! Now I just need to align the tuner, since it's off by a wide margin (96.9 is at 91 or so). I should have the last couple parts for my record changer this week, so I'll have that back in service by the weekend! Both speakers sound great (running them off the 8 ohm tap), although the L-pads are a bit scratchy, even after hitting them with deoxit. Is there some way to disassemble them for a thorough cleaning?

I'm pretty pleased with myself, especially considering all the things that could have gone wrong in replacing 13 caps in components like these for the first time ever!

Tom


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 Post subject: Re: My New 1958 Motorola Imperial Masterpiece Console -Help?
PostPosted: Apr Mon 28, 2014 6:35 am 
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Joined: Mar Tue 04, 2014 3:29 am
Posts: 2073
Location: Long Beach, CA 90808
Great Job Tom! (and Pat!)

Welcome to the fold.

_________________
Aloha, Ken

No Console Left Behind!
Come join us @ http://vintagehifi.net/


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 Post subject: Re: My New 1958 Motorola Imperial Masterpiece Console -Help?
PostPosted: Dec Sun 09, 2018 8:29 am 
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Joined: Apr Sat 18, 2015 3:01 am
Posts: 121
Location: Lexington KY
Wow this is great


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