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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Apr Fri 11, 2014 2:17 am 
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Location: Indianapolis, IN
Hey Jack---good to hear from you. Checked your website quite awhile back to view your progress---any radio pics yet ? Yes, that button adds an additional resistive load to the convertor base circuit and if the batteries are weak, it "kills" reception. Below is segment of schematic with the pushbutton switch *E1 (near center of image) and the "battery check" circuit. From what I've noticed, the CD external antenna screw was added to the later "-1" versions.

Colin---do you have the "nut" for the pushbutton ? I remembered you needed the switch, but mine came without nut. Am thinking about eliminating it from this radio because of speaker situation---but not certain, yet... If I do, you will be welcome to the switch.

John


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Motorola X31 schematic section.jpg
Motorola X31 schematic section.jpg [ 132.98 KiB | Viewed 1070 times ]
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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Apr Fri 11, 2014 12:52 pm 
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xrhonda91 wrote:
Colin---do you have the "nut" for the pushbutton ? I remembered you needed the switch, but mine came without nut. Am thinking about eliminating it from this radio because of speaker situation---but not certain, yet... If I do, you will be welcome to the switch.

John

John,
That's a very generous offer - thanks! I do have the nut for the switch. The body of the switch is still present, but the internals are missing. I think that removing the switch from your radio might detract from its looks just a little, so if I were you I would try to retain it. However, if it has to go in order to install a different speaker I will gladly accept it.

Regards,
Colin


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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Apr Fri 11, 2014 6:13 pm 
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John, I never noticed that this set had a phosphorescent dial pointer, but it seems that it doesn't hold a charge well anymore (it glowed faintly after 10 seconds under a bright light). Honestly, I am surprised they didn't use that push-button switch to control a dial light, that would have been more useful (at least in my opinion).


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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Apr Sat 12, 2014 1:21 am 
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50sTransistorRadios wrote:
Honestly, I am surprised they didn't use that push-button switch to control a dial light, that would have been more useful (at least in my opinion).


In fact the whole affair seems like a useless feature. Who really needs prior knowledge that the batteries are becoming weak yet will still power the set? I understand the need for a meter to monitor battery life on a large set with multiple batteries....I just don't see the logic in the switch on the X31A-1.

Bruce

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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Apr Sat 12, 2014 4:20 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Yes, it does seem a waste of a perfectly good switch---but guess if it was your only radio and used all the time it could be helpful in getting the most out of batteries and knowing when they're failing so you can have replacements ready...

Spent a couple hours cleaning the case more thoroughly inside and out this evening as well as notching two corners of a decent looking Pioneer 4" speaker I found in "stash" to fit this radio. Hope to get it together tomorrow. Funny, after cleaning (which removed some of the original green dye), it does look more gray... Good thing is that the many white paint specks came off with some rubbing. Certainly not pretty, but has that "weathered" look...

John


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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Apr Sat 12, 2014 4:04 pm 
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John, what did you use to clean the leather case? I used Lexol, which did a great job of removing all the dirt from the leather, but it also removed some of the dye from the leather and left it a bit sticky (although, letting it sit for a few days and wiping it thoroughly with paper towels took care of that).

Also, I figured out why the front panel is a little beat up, despite this set still having the lid; it's because the previous owner kept the lid snapped on the back of the radio, instead of protecting the front with it (I know this because the areas the case covers when snapped on backwards are darker.)


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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Apr Sun 13, 2014 4:10 am 
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Matt---I simply used a slightly damp (water) "inside-out" white cotton sock, drying immediately with another. Takes a lot of careful rubbing, but seems to get it clean without any residue or dulling of leather---but a lot of dye did come off as it appeared to have been affected by dirt build-up and possible exposure to sunlight. I also noticed the "shadows" of the cover snap tabs on this set, but both front and back positions are almost equally darker than rest of case. Didn't even think of snapping cover on back side before seeing this...

Got basically done today. Radio performs well, sound not bad---but not as good as it should be with the speaker I used, so may replace it again in the future. Noticed very little difference with the previously mentioned .01 uF disk in or out of circuit---maybe just a bit more bass "punch"... Attached two lower tabs of "new" speaker with short lengths of 5/16" ID fuel line hose over the studs retained with copper washers & screws from hardware "stash"... Did notice that tuning is easier/smoother with this set as well as the volume control being in great shape as it was---and knob "action" was much better as this set still had the original felt washers behind them... Did have an intermittent when board flexed or tapped and narrowed it down to IF transformer pins which required solder touch-up...

And I forgot to mention earlier---Motorola added an axial leaded 100 uF electrolytic above the top of PCB in later models which isn't shown in Beitmans schematic. It is in parallel "electrically" with "C20" 50 uF. Because of this, I simply replaced "C20" on this set with a 220 uF that I had on hand and it's fine...

Below are a few "not so good" pics of finished set---if you want to see some "parts pics", take a look at this thread about the 1st set: viewtopic.php?f=4&t=241357


Attachments:
ARF X31 TWINS.jpg
ARF X31 TWINS.jpg [ 132.7 KiB | Viewed 1043 times ]
ARF X31 2ND CMPL.jpg
ARF X31 2ND CMPL.jpg [ 218.58 KiB | Viewed 1043 times ]
ARF X31 2ND SPKR CMPL.jpg
ARF X31 2ND SPKR CMPL.jpg [ 245.64 KiB | Viewed 1043 times ]
ARF X31 2ND INS CMPL.jpg
ARF X31 2ND INS CMPL.jpg [ 232.34 KiB | Viewed 1043 times ]
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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Apr Wed 16, 2014 4:57 am 
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Nice work John, that set cleaned up pretty well. Maybe part of the issue with the sound quality is that the speakers in these old transistor radios are more efficient than most modern ones (they have a lighter weight cone) to get the most out of what little power many of these sets had (although this particular model has more output power than usual).


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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Apr Thu 17, 2014 12:58 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Thanks Matt...

Yes, the original Motorola speaker had a much higher quality cone and larger magnet---hope to run across a "real" parts set one day !

Sorry about the poor pics, but was tired that evening after working outdoors and my Sony camera is "finicky"...

John


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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Apr Sat 19, 2014 12:47 am 
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John,

How would you like a parts radio for the price of shipping?

I just ran across this post, and went out into the storage tubs in the garage.....

Image


Image

Send me a PM if interested.


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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Apr Sat 19, 2014 3:19 am 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Hello Dr. Radio,

Just sent a PM---thanks very much for the generous offer !

John


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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Sep Fri 11, 2020 2:03 pm 
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Joined: May Tue 05, 2009 10:21 pm
Posts: 422
Location: Princeton, NJ 08540
Hi John,

After seeing the great job that you did I decided that it was about time that I worked on my Motorola X31 that has been sitting in my attic.

The first thing that I noticed was that the front panel was bulging out on the left side and also the volume control was not centered properly. I looked inside and all of the PCB and battery mounting screws were present and were tight.

Since you completely removed your front panel on your radio I was wondering if you could give me any advice on what I should check next ?

Frank


Attachments:
Motorola X31 Loose Front Panel.jpg
Motorola X31 Loose Front Panel.jpg [ 677.88 KiB | Viewed 101 times ]
Motorola X31 Loose Front Panel 5.jpg
Motorola X31 Loose Front Panel 5.jpg [ 637.46 KiB | Viewed 101 times ]
4444.jpg
4444.jpg [ 634.72 KiB | Viewed 101 times ]
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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Sep Fri 11, 2020 4:19 pm 
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Location: Indianapolis, IN
Hey Frank, haven't heard from you in awhile !

There is a heavy press-board liner inside the leather cabinet which the front panel is attached to. I've had one come loose (glued in place) and had to re-glue it. Best that you remove chassis to attempt this so that it could be properly place in position after applying glue. Think I used Elmers Carpenter's wood glue which I had on hand. Also good to carefully clamp it using small pieces of wood (or something similar) to protect surfaces.

You could look at another thread which shows radio disassembled to see how it comes apart.

Good luck and let us know how it goes !

John


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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Sep Fri 11, 2020 5:25 pm 
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Joined: May Tue 05, 2009 10:21 pm
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Location: Princeton, NJ 08540
Thanks for the info John.

I can not find the wood glue I used to have, I guess I will have to pick up some.

Will keep you upsated.

Frank


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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Sep Fri 11, 2020 8:14 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
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Location: Indianapolis, IN
Hey Frank---it doesn't have to be wood glue, that's just what I had at the time. Just something that would bond that press-board to the similar material of leather-covered shell...

John


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 Post subject: Re: 2nd Motorola X31A-1 another "challenge"...
PostPosted: Sep Fri 11, 2020 8:27 pm 
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Elmer's white glue works well on this type of material.

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