Arvin midget radio 444a

View previous topic View next topic Go down

Arvin midget radio 444a

Post by Ben Delk on Mon Mar 13, 2017 9:30 am

Picked up a 444a a few years back just because it looked odd. I decided to work on it this weekend. What can of worms. 3 e-caps and 2 resistors had exploded. Oh no! Well cleaned it up as best I could , replace all the caps and needed resistors. Forgot to mention the speaker has no cone. The output transformer check out as does the speaker choke. There appears to be some missing or removed wire from the oscillator that is attached to the speaker. Any one have one of these little radio or clear pictures of the inside especially the speaker area connections?
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Arvin midget radio 444a

Post by John Bartley on Mon Mar 13, 2017 10:00 am

I'm sure you have already seen the schematic? :: http://www.nostalgiaair.org/pagesbymodel/518/M0012518.pdf

So, I'm looking more closely at this ... Wow! .... that is one rinky-dink, stripped down little set!  Not even an IF amp ... unless I'm missing something it goes straight from the mixer to the detector thru' an IFT, but no amplification.

And, no, I don't see anything in the schematic that indicates that there should be any connection between the oscillator and the speaker ... and that is what I was curious about in the first place, because that would have been freaky.

Edit : just noticed your comment on "speaker choke". That one lost me ... there don't appear to any chokes in this set?

John Bartley
Member
Member

Number of posts : 143
Registration date : 2013-04-21

Back to top Go down

Re: Arvin midget radio 444a

Post by Ben Delk on Mon Mar 13, 2017 10:11 am

Well oddly enough this has one . I can find very little info on the radio expect the 3 pages on nostalgia air. It is a 444 as best I can tell since the sticker on the radio is missing the model #. Just looking thru intervened picture the 444 looks to be the prize. Paid $10 for it so the tubes are worth that and they all test good. Had any luck removing speakers with choke and putting on newer type 3 ohm?
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Arvin midget radio 444a

Post by John Bartley on Mon Mar 13, 2017 10:34 am

Yup, for $10 it's not a loss at all, and if it looks at all decent it should be a winner. Does the choke look original?

When you say "choke", do you mean the "field coil" at the speaker?

cheers

John Bartley
Member
Member

Number of posts : 143
Registration date : 2013-04-21

Back to top Go down

Re: Arvin midget radio 444a

Post by Ben Delk on Mon Mar 13, 2017 11:08 am

Correct you are . It is a field coil that acts like a choke. I have another 4 inch 3 ohm speaker but it does not have a field coil. Question here is should try to remove the existing coil which is riveted to the speaker or try to add a resistor choke to the new speaker. Never done done either before so there,s a learning curve either way.
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Arvin midget radio 444a

Post by John Bartley on Mon Mar 13, 2017 11:32 am

Ahhh ok.....

So, I guess if it was me ... I'd compare the rest of the set to the schematic and try to determine if the chassis matches the schematic for that model number. If it doesn't, then I'd post up some photos to see if someone can ID the set and then once it's ID'd, find a correct schematic and go from there?

If the field coil speaker looks original to the set, and the correct schematic confirms that it should be an electromagnet type, maybe advertise for a replacement here, on ARF and elsewhere?

If the chassis looks to match the schematic, but the speaker looks like a replacement, then try to find a PM speaker and don't worry about the choking effect of the field coil?

Just some thoughts ...

John Bartley
Member
Member

Number of posts : 143
Registration date : 2013-04-21

Back to top Go down

Re: Arvin midget radio 444a

Post by willy3486 on Mon Mar 13, 2017 11:59 am

If this is the correct schematic but the speaker in it has a field coil acting like the magnet I wondered if someone has doctored it up? If its the coil used as a magnet to replace the permanent magnet, which is what I am thinking you are talking about someone might have had it already and "doctored" it into the circuit. If not done properly that would explain the burned up parts. I picked up some radios a few years ago from another collector. A couple of them had been so messed up I had to look at each part .piece by piece to make sure it was wired right. It looked like someone didn't know what they were doing and even wires were in the wrong place. I think someone gave up on it.. The other one was in similar shape. Many times the radios I find at meets look to be ones someone has messed up so much they gave up on. I wonder if this was one tinkered on and the person gave up.

willy3486
Member
Member

Number of posts : 1400
Registration date : 2011-07-02

Back to top Go down

Re: Arvin midget radio 444a

Post by Ben Delk on Mon Mar 13, 2017 12:16 pm

It has most certainly been tinkered with. Lots of cut and replaced parts. When I power it up I can see the voice coil vibrating in and out so I may try to re one it myself. I guess the next test will be to use my signal tracer to confirm I'm even receiving. Cute little radio so I hate to junk it if possible. Radio swap meet in Nashville April 13th. May see if I can find a donor there.
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Arvin midget radio 444a

Post by willy3486 on Mon Mar 13, 2017 2:25 pm

What are the tubes in  the radio? Arvin made quite a few of these radios in different configurations and cases. they made a similar one called the 402 but it has two tubes and a voice coil. One thing I am wondering is if someone took the 402 chassis and put it in the 444 case. The tubes numbers could tell more about it.  Seems like I have restored a few of these and the impression I got they made them as cheap and with as little parts as they needed. They seem to be a decent unit though. You could bring it to the Nashville meet and have someone to a quick look over of it to see if you missed anything. We all miss stuff from time to time so its good to have others see if they can find something.

http://www.radiomuseum.org/r/arvin_402.html


http://www.nostalgiaair.org/Resources/508/M0012508.htm

willy3486
Member
Member

Number of posts : 1400
Registration date : 2011-07-02

Back to top Go down

Re: Arvin midget radio 444a

Post by Ben Delk on Mon Mar 13, 2017 2:31 pm

50L6
36Z5
12SQ7
12SA7
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Arvin midget radio 444a

Post by willy3486 on Mon Mar 13, 2017 3:11 pm

By those numbers I just about bet you have a doctored radio. Post links to pictures of the chassis and case if you have them. I went through a few of the radios at Nostalgia air and I could not find any with electromagnets other than the 402. I didn't go through all just some around the late 40s to early 50s. They were made by Noblitt Sparks.

http://www.nostalgiaair.org/Resources/278/T0000278.htm

willy3486
Member
Member

Number of posts : 1400
Registration date : 2011-07-02

Back to top Go down

Re: Arvin midget radio 444a

Post by Ben Delk on Mon Mar 13, 2017 4:25 pm

You know you may be on to something there. The picture of the 444 is the cabinet I have and the tubes match but the speaker setup does not. Some of the caps I removed we odd size looking at the schematic but that's nothing new when someone has been in it before you. I replaced everything according to the 444 schematic so I'll use the signal tracer tonight and if I have music on it then I try the spare 3 ohm pm speaker I have. I'm thinging it's a little large for a paper weight😊
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Arvin midget radio 444a

Post by Bill Cahill on Mon Mar 13, 2017 9:24 pm

John Bartley wrote:Ahhh ok.....

So, I guess if it was me ... I'd compare the rest of the set to the schematic and try to determine if the chassis matches the schematic for that model number. If it doesn't, then I'd post up some photos to see if someone can ID the set and then once it's ID'd, find a correct schematic and go from there?

If the field coil speaker looks original to the set, and the correct schematic confirms that it should be an electromagnet type, maybe advertise for a replacement here, on ARF and elsewhere?

If the chassis looks to match the schematic, but the speaker looks like a replacement, then try to find a PM speaker and don't worry about the choking effect of the field coil?

Just some thoughts ...

The field coil is meant to be an electro-magnet for the speaker.
I'd say it's original. Not an install replacement.
The best place to get the dc voltage it needed was in the power supply, though I have seen some of them connected to the negative of the filters.
It made it cheaper to make the radios. Less filtering in cans, and, less resistors.
Hope this helps.
Bill

_________________
Please also join us here;  http://videokarma.org/index.php
avatar
Bill Cahill
Admin
Admin

Number of posts : 4538
Age : 66
Registration date : 2008-03-12

Back to top Go down

Re: Arvin midget radio 444a

Post by John Bartley on Mon Mar 13, 2017 9:44 pm

Bill Cahill wrote:

The field coil is meant to be an electro-magnet for the speaker.
I'd say it's original. Not an install replacement.
The best place to get the dc voltage it needed was in the power supply, though I have seen some of them connected to the negative of the filters.
It made it cheaper to make the radios. Less filtering in cans, and, less resistors.
Hope this helps.
Bill

Hi Bill,

Good to hear from you. In this case the schematics that are for this series of radios do not show an Electro-Dynamic speaker. There is no indication of a field coil anywhere on the schematics. That is why the discussion about previous repairs.

cheers


John Bartley
Member
Member

Number of posts : 143
Registration date : 2013-04-21

Back to top Go down

Re: Arvin midget radio 444a

Post by Bill Cahill on Mon Mar 13, 2017 9:47 pm

My guess is he's got an earlier chassis. But, you could be right.
Thank you, John.
Bill

_________________
Please also join us here;  http://videokarma.org/index.php
avatar
Bill Cahill
Admin
Admin

Number of posts : 4538
Age : 66
Registration date : 2008-03-12

Back to top Go down

Re: Arvin midget radio 444a

Post by Ben Delk on Tue Mar 14, 2017 8:57 am

Got the old magnifying glass out and found a faint trace of the schematic still attached to the metal cabinet. It is indeed a 444a.
The sticker shows a top side view of the tubes and a field coil attached to the speaker. I put it back on the "look it this later" shelf. I'm going to a swap meet in a few week and may find a donor radio like it. For now I have moved on to a spartan 600. Thanks guys.
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Arvin midget radio 444a

Post by Ben Delk on Tue Mar 14, 2017 9:03 am

Oooops I meant spartan 601s
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Arvin midget radio 444a

Post by willy3486 on Wed Mar 15, 2017 7:55 am

Ben Delk wrote:Got the old magnifying glass out and found a faint trace of the schematic still attached to the metal cabinet. It is indeed a 444a.
The sticker shows  a top side view of the tubes and a field coil attached to the speaker. I put it back on the "look it this later" shelf. I'm going to a swap meet in a few week and may find a donor radio like it. For now I have moved on to a spartan 600. Thanks guys.

That field coil you see wouldn't be the audio transformer going to the speaker would it? A lot of speakers have the audio transformer mounted on the speaker, the last radio I did had that and the transformer was junk. In the diagram of the 444a on nostalgia air it is part t4 on the diagram. If you bring it to the meet bring the schematic and look me up. Most of the vendors know me.


There is a page with pictures of a 444a on the link. The audio transformer of the radio is mounted on the speaker in one of the pictures. If your radio chassis looks exactly like this setup except for the speaker has a field coil I think it has been added by a previous repairman and not original.
http://www.capeoldradio.com/cor_radio.php?radio_box=25491

willy3486
Member
Member

Number of posts : 1400
Registration date : 2011-07-02

Back to top Go down

Re: Arvin midget radio 444a

Post by Ben Delk on Wed Mar 15, 2017 9:06 am

That is the radio and the coil is mounted to the speaker. Great find, thanks. I'll bring it when I come to the swap meet. I'm looking to pick up a dozen or so fixer uppers as well. Will you have table there?
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Arvin midget radio 444a

Post by willy3486 on Wed Mar 15, 2017 2:09 pm

Ben Delk wrote:That is the radio and the coil is mounted to the speaker. Great find, thanks. I'll bring it when I come to the swap meet. I'm looking to pick up a dozen or so fixer uppers as well. Will you have table there?

If the coil looks like that it may be the audio transformer. Sometimes you will only see 2 wires out to the tube from a transformer. The other two are small gauge wire to the speaker. I don't sell there, I probably should I have so much junk I need to get rid of. I usually find projects there. Its a good place to find projects. Most of the projects I get usually run from 5 to 30 bucks. Mine are usually bucket cases or ones not collectable,yet. I wind up with 3 or 4 usually. I have so many now I usually look for schematics and advertising. I also like to find junk for parts.

willy3486
Member
Member

Number of posts : 1400
Registration date : 2011-07-02

Back to top Go down

Re: Arvin midget radio 444a

Post by Ben Delk on Wed Mar 15, 2017 2:29 pm

I know there were 2 wire coming up from the bottom to the coil then I think only 2 out of the coil, one to each leg of the speaker. Can't remember now for sure. I put the 444 back on the shelf and moved on.

Like you I don't go for high end stuff unless one falls my way but I don't unusually pay more than $30 and try to make sure everything there when I do. I prefer the wooden radios. Just looking for something to play with. I don't sell any unless they are close friends . I'll try to catch you at the swap meet. My wife will be with me so she is eariernto look for... beautiful lady with gray hair spiked straight up. Our Honda van has a license plate that says Spike51.
avatar
Ben Delk
Member
Member

Number of posts : 443
Age : 67
Registration date : 2012-04-03

Back to top Go down

Re: Arvin midget radio 444a

Post by Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum