View Full Version : 1949 Magnavox MV13BS Restoration


davet753
08-06-2016, 06:04 PM
I bought this from the estate of an old friend who was an engineer at Magnavox in the 80's and 90's. It came from the museum that used to be at their engineering and sales office in Knoxville. The chassis is very original, and appears to be unmolested. There is one caveat....the CRT is missing.

I am now in the market for a good 12KP4 picture tube.

timmy
08-06-2016, 08:38 PM
I bought this from the estate of an old friend who was an engineer at Magnavox in the 80's and 90's. It came from the museum that used to be at their engineering and sales office in Knoxville. The chassis is very original, and appears to be unmolested. There is one caveat....the CRT is missing.

I am now in the market for a good 12KP4 picture tube.

I have a 12lp4 that I think is nos and tests like new but I don't know of a fool proof way of shipping it without getting damaged.

Steve McVoy
08-07-2016, 05:50 AM
We have a good used 12KP4A at the museum for sale:

http://www.earlytelevision.org/crts_for_sale_b-w.html

We ship these all the time by Fedex Ground, double boxed, and have never had a broken tube.

Crist Rigott
08-07-2016, 07:17 AM
Steve,
I didn't know the EFT had such a listing. I searched the website and couldn't find where to click to bring up this page. Could you let me know how to get there from the Home page?

Thanks.

Steve McVoy
08-07-2016, 07:46 AM
The link is in my previous post.

davet753
08-07-2016, 05:38 PM
It looks like I'm also going to need to do some work on mounting the CRT (once I find one). The yoke is held in place in a bracket attached to the chassis, and there are two support brackets with rubber bumpers to support the bottom of the screen. I'm missing whatever bracket holds the tube secure.

I'd prefer to use the 12KP4 if at all possible. I understand it is brighter than some of the others of that era, and would be a direct replacement for what the set was made for. Of course, I may have to end up being happy with just finding something that will work.

WISCOJIM
08-07-2016, 05:48 PM
two support brackets with rubber bumpers to support the bottom of the screen. I'm missing whatever bracket holds the tube secure. Pictures of the mounting assembly and model number, please. I know there's an old round Maggie sitting in one of my storage bins, maybe it has the same setup...

.

davet753
08-08-2016, 09:01 PM
Pictures of the mounting assembly and model number, please. I know there's an old round Maggie sitting in one of my storage bins, maybe it has the same setup...

.

THanks for the help! Here are some pics of the inside. One shows the cabinet, one the yoke assembly, and one shows the rubber bumpers the front of the picture tube rests on.

Someone had taped a piece of smoky plastic over the inside front, and I haven't cleaned off the tape yet.

THe television is a Magnavox model MV13BS. In 1949, they called the model the "Modern Symphony". It sold for $395.

The

WISCOJIM
08-08-2016, 10:18 PM
I'll head out to the storage sometime this week to see if the set I have can help yours.

.

davet753
08-09-2016, 06:18 PM
Thanks for the help, I sure appreciate it. I have acquired a picture tube, so it looks like this project should be getting underway in the near future.

WISCOJIM
08-16-2016, 11:39 AM
I brought the Magnavox back to the garage this morning. Sorry, the mounting of the CRT doesn't match, so I can't help you with that.

Maybe next time?

.

davet753
08-17-2016, 06:28 PM
I brought the Magnavox back to the garage this morning. Sorry, the mounting of the CRT doesn't match, so I can't help you with that.

Maybe next time?

.

Thanks for looking. I think I can fabricate something to hold it in place.

The diagram arrived in the mail today, and it shows an ion trap on the neck of the tube (the Photofact shows a 10BP4, but the sticker in my cabinet shows a 12KP4). At first, I thought that would be something else I would need, but seems like I remember reading somewhere the 12KP4 didn't require an ion trap.

Eric H
08-17-2016, 07:46 PM
KP4's do not need a trap, provided it was never rebuilt with a bent gun, that would be a rare scenario. The schematic no doubt covers several models including a 10".

ohohyodafarted
08-19-2016, 11:56 AM
I have the exact same model in my collection. It has a 12KP4, and you are correct, the tube chart calls for a 12K.

My set has not been restored yet. I hope to get to it some day. I got my set from someone in the Chicago area on Craigslist for $40.

Scroll down the page to find the thumbnail
http://antiquetvguy.com/WebPages/TheSets/Menu-BW%20Sets/BlackAndWhiteSets.html

davet753
08-30-2016, 08:17 PM
Replaced all the wax dipped capacitors, and slowly brought up the line voltage to 100 volts...lo and behold, I have a raster.

Now that I know I have something good to work with, it's time to dig in and get this set working again.

davet753
09-06-2016, 06:39 PM
The horizontal oscillator is a little unstable, so I'm going to need to check resistor values in that circuit. Other than that (and linearity/centering adjustments), I think she's ready to go back in the cabinet.

davet753
11-27-2016, 07:07 PM
I have luckily heard from another Videokarma user who restored a set almost matching mine. His is an earlier version, and has a 10" tube instead of the 12" in my set. Here is a pic of the label showing where my set calls for a 12KP4.

Also, if anyone knows how to change the title on a thread, I'd like to know how since this thread is about more than needing a tube.

Electronic M
11-27-2016, 11:22 PM
I have luckily heard from another Videokarma user who restored a set almost matching mine. His is an earlier version, and has a 10" tube instead of the 12" in my set. Here is a pic of the label showing where my set calls for a 12KP4.

Also, if anyone knows how to change the title on a thread, I'd like to know how since this thread is about more than needing a tube.

What exactly do you want the title changed to?

davet753
11-29-2016, 06:01 PM
1949 Magnavox MV13BS Restoration

Electronic M
11-29-2016, 08:33 PM
Done.

kramden66
11-29-2016, 09:42 PM
Nice picture , if you don't have a 12kp4 what are you using in the pics?

davet753
12-04-2016, 05:00 PM
It is a 12KP4. When I got the set, the CRT was missing, and I went by the sticker on the inside of the cabinet that said 12KP4. The Sams Photofact says its supposed to be a 10BP4, and I got a PM from a member who has one identical to mine...but it has a 10BP4.

Oddly enough, Magnavox evidently made this model using two different size picture tubes, but the same face mask. While mine has a 2" bigger picture tube, the viewable size is the same as the ones with a 10" tube.