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 Post subject: Majestic model 90 rebuild
PostPosted: May Mon 30, 2016 11:37 pm 
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This is a mixed bag. Picked this up from Craigslist. All the tubes are there and one 45 tests just into the green and the other strong. In reading some posts I noted that the pot metal mounts for the tuning caps were an issue so I pulled it apart for inspection and there is some warping. The pot metal has not turned to powder or crumbled but does have some cracks showing. I am guessing that resolving this will determine if I even want to move ahead with the chassis. In the picture you can see the rotors look fine. The center of the stator looks fine. The outside fins of the stator have splayed away from the middle. So the questions are;

1. Is this fixable? Can I move the fins back into place without damaging the pot metal?
2. Are there any other options?

I don't have a lot in this set and don't want to invest a bunch of time for nothing. This is just for my collection not trying to flip it.


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Last edited by black85vette on Nov Thu 24, 2016 4:51 am, edited 1 time in total.
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 Post subject: Re: Majestic model 90 questions
PostPosted: May Tue 31, 2016 2:18 am 
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There should be an adjustment at the back end of the tuning mechanism in which the shaft connects to. It may need adjustment. I don't know if the 90 has this adjustment or not.

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 Post subject: Re: Majestic model 90 questions
PostPosted: May Tue 31, 2016 3:08 am 
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I don't think a tuning cap adjustment will help. Looking at the top plates of the full section in the center of the photo, the rotor would need to be moved towards the top, but this would insure that the rotor plates at the bottom of the section will short to the stator if they aren't already. It appears that the rotor has shrunk. Other than replacing the cap, I'm not sure this can be fixed.

John

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 Post subject: Re: Majestic model 90 questions
PostPosted: May Tue 31, 2016 4:20 am 
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Are the cast pieces that hold the plates all one piece with the shaft? If not, is there some way to move the cast pieces with respect to each other? Then maybe you could move the entire assembly up a bit and allow all the plates to clear. Just a thought...

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 Post subject: Re: Majestic model 90 questions
PostPosted: May Tue 31, 2016 1:19 pm 
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AuldSparkie wrote:
Are the cast pieces that hold the plates all one piece with the shaft? If not, is there some way to move the cast pieces with respect to each other? Then maybe you could move the entire assembly up a bit and allow all the plates to clear. Just a thought...


The cast pot metal pieces hold both ends of the stator fins. The rotor fins look fine. If you look at the stator fins on end instead of the fins looking like a comb with the fins parallel they look more like a fan with the left side tilted left the center straight and the right side tilted right. So moving them all to one side or the other won't help. As John pointed out replacing the cap may be the only solution, IF I can find one without this problem.

I may just tear into it and pull the cap apart. What the heck, it won't work like it is anyway. Just thought I would get some input and options before doing something stupid that can't be undone.

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 Post subject: Re: Majestic model 90 questions
PostPosted: May Tue 31, 2016 3:25 pm 
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Only about 1 in 100 of these tuning caps are still good. This is why I have always just used 90s for parts. Oh and besides, it takes 2 or 3 guys to get it into the display area and the power supply might come sliding out and drop on your foot.

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 Post subject: Re: Majestic model 90 questions
PostPosted: May Tue 31, 2016 3:56 pm 
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phlogiston wrote:
Only about 1 in 100 of these tuning caps are still good. This is why I have always just used 90s for parts. Oh and besides, it takes 2 or 3 guys to get it into the display area and the power supply might come sliding out and drop on your foot.


So the chance of finding a good cap is pretty small then. :(

Yeah, why did they not bolt down the power supply?????

Don't know about the 2 or 3 guys since my wife and I carried it from the truck into the house. So maybe 2-3 guys if they are not as strong as my wife?? :lol:

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 Post subject: Re: Majestic model 90 questions
PostPosted: May Tue 31, 2016 5:17 pm 
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black85vette wrote:
phlogiston wrote:
Only about 1 in 100 of these tuning caps are still good. This is why I have always just used 90s for parts. Oh and besides, it takes 2 or 3 guys to get it into the display area and the power supply might come sliding out and drop on your foot.


So the chance of finding a good cap is pretty small then. :(

Yeah, why did they not bolt down the power supply?????

Don't know about the 2 or 3 guys since my wife and I carried it from the truck into the house. So maybe 2-3 guys if they are not as strong as my wife?? :lol:



Yep.

It's upstairs.

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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Wed 01, 2016 8:50 pm 
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I might have a spare cap in my stash. I can check if you like.

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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Wed 01, 2016 11:16 pm 
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badwaxcaps wrote:
I might have a spare cap in my stash. I can check if you like.


Sure. It looks to be a show stopper on this project. It certainly is not going to be recap and replace a tube!

Thanks!

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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Thu 02, 2016 12:37 am 
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Hi Rick

Don't feel too bad. I've never had a Majestic 90, here in California, with a good 5 section tuner. Some are so warped look more like petals of a flower.

There are a couple things that can be done. Replace the tuner with a 3 or 4 section type, not Majestic. It takes work remounting and changing a little circuitry but will operate.

Another person used washers between plates in place of pot metal. He said it was a lot of work but turned out alright.

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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Thu 02, 2016 1:35 am 
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I'll dig into my parts tomorrow and see what I have. I'll letcha know.

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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Thu 02, 2016 1:42 am 
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@badwaxcaps; thanks for checking.

@norm; I may tear into it and see. I have a machine shop here at the house and have fabricated replacement parts for Atwater Kent pot metal pieces. I guess this is my lack of experience showing. If I had known about the problems with this set I may have just passed on it. But each one is a learning experience and it is just a hobby for me so time is not an issue.

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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Thu 02, 2016 8:55 pm 
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What would Grugsby-Grunow Majestic have thought if they had known we'd all be cussin' at their pot metal capacitors 85 years later? :lol:

I actually have an unmolested Majestic 52 that works and tunes in stations. I had thought about recapping it, but after a half hour plotting a strategy to disassemble it, I decided NO WAY!

Now I just plug it in for 5 minutes about every 6 months and pray.

Mark K8KZ


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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Thu 02, 2016 10:14 pm 
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markmoke wrote:
but after a half hour plotting a strategy to disassemble it, I decided NO WAY!

Mark K8KZ


Yeah I have a few choice words for them, but no worse than for GM engineers when we rebuilt a 67 Camaro. Some parts were never intended to be serviced or replaced.

I have the capacitor out and sitting on my bench but getting the rotor out is a puzzle. Shaft is too long to slide it out and the bushing on the end in the frame keeps you from going out at an angle. < Anyone take one of these apart before??? If I HAVE to I can make a tool to press the bushing out and that might do it. Now it is a challenge and I hate to lose!>

Edit; only took 10 min to make a die to go over the shaft, push on the bushing and clear the hole in the frame. Used a hammer to drive the bushing out and then the shaft tilted up and cleared the stators. However, after removing a stator I see how much it is fanned out and expanded. Even putting it in a bench vise did not take it back to its original dimension. :twisted:

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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Fri 03, 2016 12:11 am 
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I'm looking through my stuff. I know I have a couple Majestic chassis and power supplys in there. Its the preverbial "black hole" though.

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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Fri 03, 2016 12:21 am 
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badwaxcaps wrote:
I'm looking through my stuff. I know I have a couple Majestic chassis and power supplys in there. Its the preverbial "black hole" though.


If you have the power supply for this radio let me know about that also. This came without one because I didn't know to look for it. :oops:

Thanks again.

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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Fri 03, 2016 2:45 am 
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If you are looking for the 40 lb foot-breaking box, I know that I have one unrestored and one for a 70 too.

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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Fri 03, 2016 1:27 pm 
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phlogiston wrote:
If you are looking for the 40 lb foot-breaking box, I know that I have one unrestored and one for a 70 too.


Thanks for the offer. I want to wait and see about the cap first. If I can't get a working cap then I won't need the power unit.

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 Post subject: Re: Majestic model 90 questions
PostPosted: Jun Fri 03, 2016 11:07 pm 
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Good news, bad news.

Good news is I found the spare 90 chassis.

You can probably guess the bad news. The two foremost gangs are rubbing. The other three are clear but the pot metal on them is starting to crack pretty bad. I did find the extra power supply as well but its a bit of a wreck. The wiring has been kludged and the resistors up top are boogered up. I'm sorry its not gonna be much help :(

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