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Author Topic: Majestic Radio  (Read 2831 times)

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DaOld Man

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Majestic Radio
« on: April 23, 2021, 09:13:50 am »
My GF has a very old Majestic Radio. Made by Grigsby-Grunow company. Im guessing it was made in early 30's or late 20's.
This thing is heavy, no idea if it works, I'd thought I would play around with it to see if I could get it working.
Sorry if this is not the right forum to post this, just thought it might interest you guys, and maybe someone can give me more info on it.
Any idea what it is worth, cause she said she may sell it.

Here is the front, doors closed.


Doors open (knobs are missing):


Boiler tag on the receiver unit:


Boiler tag on the power supply (this thing is very heavy, Im guessing it has a big transformer in the box):

nitrogen_widget

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Re: Majestic Radio
« Reply #1 on: April 23, 2021, 12:24:31 pm »
vacuum tubes?

DaOld Man

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Re: Majestic Radio
« Reply #2 on: April 23, 2021, 02:38:17 pm »

DaOld Man

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Re: Majestic Radio
« Reply #3 on: April 23, 2021, 02:40:54 pm »
Here is a schematic I found for it.

Mike A

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Re: Majestic Radio
« Reply #4 on: April 23, 2021, 03:13:59 pm »
Cool.

nitrogen_widget

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Robbbert

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Re: Majestic Radio
« Reply #6 on: April 23, 2021, 08:51:52 pm »
You've poked me in my favourite hobby damn you.

If that schematic is correct, then you have a TRF radio, which means a whole bunch of tuning knobs to adjust whenever you choose another station (it's AM band only). Some really expensive TRF radios had the adjustments linked up with a chain or some other means.

If you're planning on powering it up, make sure you replace all the capacitors with modern equivalents with suitable voltage ratings. Then check the values of all the resistors and replace as needed. The radio is so old that even the insulation on the wires could have rotted away, so then you'll have to replace all of them too. Don't forget the power cord - the insulation is probably rubber which will have perished ages ago.

If you just plug it in without checking, you'll either destroy all the irreplaceable parts, or you'll start a fire.

Be very careful with the valves (tubes). If you break one, then you're unlikely to find a replacement any time soon.

The schematic doesn't show the power supply - I'm assuming it's mains powered, but perhaps it runs on unobtanium batteries.

AS for its worth - it would have been pricey back in the day, but whether that excites anyone today is another matter.

Good luck?

EDIT: I see the photo only shows 3 knobs (which appear to be missing). So I'm not at all sure the schematic matches this radio. Perhaps you could look inside and see what valves are there, and how many.
« Last Edit: April 23, 2021, 08:59:27 pm by Robbbert »

BadMouth

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Re: Majestic Radio
« Reply #7 on: April 24, 2021, 10:13:16 am »
You've poked me in my favourite hobby damn you.

I picked up a Wards Airline at a thrift shop for $30 with the intention of installing a bluetooth amp to play old time radio streams.
But everything was there, so I stopped after refinishing the cabinet and vacuum molding a new dial cover.  It is just decoration at this point.  I am not sure how much AM radio I would listen to anyway.  It does do shortwave which might be interesting.

Someone cut the power and speaker wires off of it.  I am not sure if they did this to get the copper or to prevent a dangerous situation of it being plugged in.

Is there any way to tell if someone already borked it by trying to power it up without replacing the caps?
It would be cool to see the cathode ray tuning eye glow.

« Last Edit: April 24, 2021, 10:52:04 am by BadMouth »

Robbbert

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Re: Majestic Radio
« Reply #8 on: April 24, 2021, 12:26:19 pm »
That looks quite nice, although newer than DaOldMan's radio. There's a knob missing, but it has push buttons for tuning, like a car radio. I'm jealous.

I can understand cutting off the power cord, but the speaker? That's weird.

The trouble with American radios is they often don't have a power transformer, with the valve heaters simply wired in series. You can get electrocuted just by touching exposed metalwork.

My collection is mostly Australian radios, and they always have a transformer, and the chassis can (and should) be earthed. Much safer.

If I had that radio and lived in your country I'd certainly be looking to repair it and reconnect the wires.

Tuning indicators look cool, with a lovely green glow. Unfortunately the old type (such as yours) tend to have a short life. They go dim and eventually don't glow any more. Further, nobody in the world makes replacements. It's a sad situation.

EDIT: actually you can get a valve called 6E5C from Russia, but you might have to rewire the radio a bit to get it in.
« Last Edit: April 24, 2021, 12:29:13 pm by Robbbert »

Vigo

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Re: Majestic Radio
« Reply #9 on: April 25, 2021, 03:21:57 am »
I am not sure how much AM radio I would listen to anyway. 

I would probably try to get a low power AM transmitter and a cheap MP3 player and put them in or near the radio, left always on. Then I would fill the MP3 player with early radio shows and music and pick it up as if it was an actual station. Heck of a cool piece if you can turn on Some Dick Tracy Show or Duke Ellington whenever you turn the radio on.

DaOld Man

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Re: Majestic Radio
« Reply #10 on: April 25, 2021, 07:21:08 pm »
You've poked me in my favourite hobby damn you.

If that schematic is correct, then you have a TRF radio, which means a whole bunch of tuning knobs to adjust whenever you choose another station (it's AM band only). Some really expensive TRF radios had the adjustments linked up with a chain or some other means.

If you're planning on powering it up, make sure you replace all the capacitors with modern equivalents with suitable voltage ratings. Then check the values of all the resistors and replace as needed. The radio is so old that even the insulation on the wires could have rotted away, so then you'll have to replace all of them too. Don't forget the power cord - the insulation is probably rubber which will have perished ages ago.

If you just plug it in without checking, you'll either destroy all the irreplaceable parts, or you'll start a fire.

Be very careful with the valves (tubes). If you break one, then you're unlikely to find a replacement any time soon.

The schematic doesn't show the power supply - I'm assuming it's mains powered, but perhaps it runs on unobtanium batteries.

AS for its worth - it would have been pricey back in the day, but whether that excites anyone today is another matter.

Good luck?

EDIT: I see the photo only shows 3 knobs (which appear to be missing). So I'm not at all sure the schematic matches this radio. Perhaps you could look inside and see what valves are there, and how many.

I found a video on you tube showing this radio does have a tuning coil actuated by a lever rod that is attached to a knob, not sure where though, maybe one of the missing knobs on the front?
The power supply is a very heavy box. May have batteries in it I dont know. I figured it contains an old heavy transformer.
I havent done anything at all to it yet, but I have taken more pictures of the inside. Will post them soon.

DaOld Man

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Re: Majestic Radio
« Reply #11 on: April 25, 2021, 07:45:25 pm »
More pics.

This is the speaker and to the right of it is the power supply.



Here is a shot of the receiver. Not sure what the box is in front of the tubes. 2 tubes (valves) or maybe three. Looks like there may be a tube socket int the front (of pic, actually facing back of cabinet), that may have had a tube in it.
If so at least one tube is missing.



Another shot of the speaker. Not sure what that thing is mounted to the wall, to left of speaker. Maybe a line filter???



And finally, a shot of the tuning cap, enclosed in a metal box. (Im pretty sure it is the tuning cap.)




bobbyb13

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Re: Majestic Radio
« Reply #12 on: April 26, 2021, 04:27:41 am »
That is such a cool unit (and I have no idea what the hell I am looking at in there really either.)

Makes you wonder exactly what its history is.
Appears in great shape for something probably quickky approaching a hundred years old!
What's that watermelon doing there?

Robbbert

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Re: Majestic Radio
« Reply #13 on: April 26, 2021, 07:41:26 am »
Thanks for the photos.

Firstly, I had another look at the schematic (assuming it's the right one). There's 5x type 27 tube, which you can still buy online for about $15 each. The first 4 are straight RF amps, and the last is what I believe is called the anode-bend detector (it's really ancient technology that soon fell out of favour). The last 2 tubes are type 45 which are rather more expensive, $70 or more (or a lot more), wired as a push-pull audio output stage. The speaker transformer (probably part of the speaker assembly) converts the valve's high voltage low current to the speaker's need for low voltage high current. Every valve radio has a speaker transformer, although the rest of the technology evolved over time.

As for the power supply, if it's an AC type (plugs into the wall socket), there will be a transformer, a rectifier valve (most likely type 80), some smoothing capacitors (which will need replacing), and perhaps a choke. Most radios of that age didn't have a choke, but instead used a winding on the speaker for that purpose. That's because magnet technology wasn't up to speed back then, and the magnetic field of the choke winding did the job instead.

If the power supply is a battery type, then all that's in there will be various batteries, all gone flat or leaking by now.

However, if we once again depend on the schematic, voltages exceeding 300 volts are mentioned, and these would only come from an AC supply. You can imagine what 300 volts would do to old dud capacitors. That's why you should replace all of them before even thinking about applying power.

Robbbert

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Re: Majestic Radio
« Reply #14 on: April 26, 2021, 08:08:30 am »
Now to your photos. The speaker unit looks quite complex, but in fact is fairly standard for that time. There will be the field winding (the choke winding mentioned above), the speaker transformer and the voice coil winding. Today's speakers only have the voice coil, the rest no longer needed. So, don't ruin the speaker unit, it's irreplaceable. But does it work? You'll need your multimeter set to ohms, and make sure the field coil is intact (should measure several hundred ohms or so). The primary of the speaker transformer must conduct between all 3 pins (being a push-pull unit). And lastly the secondary, which joins to the voice coil, must conduct as well. The most likely failures are the field coil and the primary winding, both of which are fatal to your radio, I'm afraid.

As to the cylindrical unit near the speaker, I couldn't really say, it could be anything. Given the age, it might even be a baretter, another lost piece of technology. A baretter looks like a fancy light globe, and performs the task of a current regulator. Like any light globe it has a filament that can blow.

Further analysis can only be performed by removing the receiver chassis, turning it over and seeing what lies underneath (but be careful with those valves).

Mike A

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Re: Majestic Radio
« Reply #15 on: April 26, 2021, 09:21:53 am »
So you are saying you know a little bit about this stuff. ;)

That is valuable information.


yotsuya

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Re: Majestic Radio
« Reply #16 on: April 26, 2021, 05:29:06 pm »
I say just plug that ---smurf--- in and run...




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yotsuya

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Re: Majestic Radio
« Reply #17 on: April 26, 2021, 05:29:40 pm »
But in all seriousness, great info Robbbert!


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pbj

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Re: Majestic Radio
« Reply #18 on: April 26, 2021, 09:41:17 pm »
Plug it in anyway.
I aspire to be involved in the classic gaming community.

DaOld Man

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Re: Majestic Radio
« Reply #19 on: April 27, 2021, 09:00:15 am »
Here is a complete screen shot of the schematic that I have for it:


DaOld Man

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Re: Majestic Radio
« Reply #20 on: April 27, 2021, 09:11:01 am »
The schematic is for models 91 and 92, not 90, which is the one I have, so schematic may not be exact.
Also the power supply is AC, if you look on the boiler tag for it I posted earlier, you can see the voltage on it. (115 VOLTS AC 50 or 60 cycles)

Also as far as plugging it in, I would if I knew for sure it wasn't worth anything. I would hate to completely destroy such an antique, if there was any chance someone may want it to repair.
Think of just plugging in an original never touched Donkey Kong cabinet, that hadn't been powered up in years. It would be very irresponsible to not go over it real good first.
This baby is a lot older than any Donkey Kong cabinet. Probably older than any of us.

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Re: Majestic Radio
« Reply #21 on: April 27, 2021, 08:15:45 pm »
Yep, i'd place it at late-20s or early-30s.

Unfortunately it's hard to say it's worth $xxx, because the value of it lies in the beholder. If you manage to find the right collector you might get a good price. There's just so many things that could have gone wrong with it (look at all those coils and transformers), and some things just have to be replaced (capacitors).

Sounds like you don't want to fix it or keep it, so it would be great if you can find it a good home.

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Re: Majestic Radio
« Reply #22 on: April 29, 2021, 05:01:39 pm »
Late 20's is only a few years away.  Damn.

That's a very cool piece of history!

nitrogen_widget

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Re: Majestic Radio
« Reply #23 on: April 29, 2021, 10:46:59 pm »
I see only one choice here.
install an echo dot, pair it up to a Bluetooth speaker inside facing backwards so it reflects off the wall, yank that speaker and place one of these bad boys inside.




you do NOT have to propose like in the picture.
that's just silly.
you need silver and gold dancing party lights to do that.