HFU HF Underground
Technical Topics => Equipment => Topic started by: ChrisSmolinski on December 23, 2018, 1852 UTC
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I picked up this Crosley J30BC antique radio from the Goodwill store for $10 as a restoration project. Looks to be from circa 1940/1941? One of the tubes is definitely damaged, and the wiring is brittle.
(https://i.imgur.com/xmaZhq0.jpg)
(https://i.imgur.com/CTd7Evf.jpg)
(https://i.imgur.com/LpkybrV.jpg)
(https://i.imgur.com/79cdrEW.jpg)
(https://i.imgur.com/3vJ0fcG.jpg)
(https://i.imgur.com/ATtVHtz.jpg)
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Neat layout, hopefully that tube count indicates it has a 1st rf. If so, should be a decent sw/ambc performer with thunderous audio.
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The broken tube looks like a 5U4G with an ST shaped envelope. Very common and easy to find.
Looks like a cool rig. I'm in the process of getting my great grandfather's late thirties Cornado floor radio going again too. I'll put a vijeo on youtube when I get it finished.
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The broken tube looks like a 5U4G with an ST shaped envelope. Very common and easy to find.
Looks like a cool rig. I'm in the process of getting my great grandfather's late thirties Cornado floor radio going again too. I'll put a vijeo on youtube when I get it finished.
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I have my great grandparents late 1930s GE floor radio for about 15 years now as a restoration project. It works electrically (ironically the only bad tube in it was the rectifier), but still needs cosmetic work.
Eventually I'll get them done and be able to listen to X-FM on them ;D
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I saw a pristine version of that Crosley at an estate sale about 25 years ago. It was sweet. They wanted 275$ for it then. I thought about the old, "It followed me home", wheeze, but my wife was there.
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Classic... could have been in someone's living room when the latest Glenn Miller tune was interrupted to announce the air raid on Pearl Harbor.
Those 6K6s driving a speaker in a wood cabinet should fill the room with nice audio.
Is that coil arrangement some kind of tunable variometer?
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It appears to be Crosley's version of the 'wave magnet' or loop antenna.
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NICE!!!! I could imagine listening to the amateur radio AM QSO's on 75M and those Saturday night Newsline transmissions on 160M 1860kHz AM from Missouri, on this console. And, maybe even a pirate catch on 1710kHz. That turntable? Should be good for 78RPM's, and maybe even 16RPM's. And, that speaker could see new life with a silicon lubricant on the cone and diaphragm and give you that nice, rich, deep bassy, tone quality. (Not petroleum based lubes, since they could dissolve the glues.)
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That's a 5Y3 G 8), 5U4's are commonly found in TVs .
Chris , you'll need to swap out every paper capacitor with modern caps before you apply any power . Slide shrink wrap sleeves over the wires with crumbling insulation.
It's a fairly simple operation , but there are numerous things that are critical you'll need to know as you go. I don't know your skill level but it's easy to mess up
If you need help or advice , don't hesitate I have done more than 50 . Feel free to e mail. Davepear56@ gmail
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Thanks for the tips, Dave. My plan is to completely change out the AC power cord of course, since there is virtually no insulation left. I have not had a chance to inspect the radio itself yet, but I just got it removed from the cabinet, along with the turntable.
Regarding the cabinet, the fabric in front of the speaker is completely destroyed as you can tell from the photo (but the speaker itself looks OK from a quick check). I am not sure how to go about replacing it. It looks like it is sandwiched between the front of the cabinet and a piece of wood behind it. I was going to remove that wood, but I cannot get to some of the screws, and even if I could loosen them all, I am not sure there is clearance to remove it. Or am I missing an easier way to do this?
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https://www.tubesandmore.com/sites/default/files/schematics/crosley_corp_j30bc_pg12-1.png
First thing is replace the 10 mfd / 15 mfd/ 15mfd electrolytics shown between the 5y3 and the speaker connections on the schematic.
These will be rated at 450volts . After that all the ones such as .1mfd , .02 etc that are paper and those need to come out and be replaced with modern same or near the capacity marked on the old ones. Complete each one before moving on ( Important!). At that point after making sure nothing is touching each other or shorted from handling, you can usually apply AC , stand back, the majority of old radios will work with this minimum. Once you get it working and picking up a station , other issues like intermittents or poor contacts can be worked out. There may be out of spec resistors in a Radio that old here and there but not so bad as to keep it from working and can be dealt with later. When replacing the caps cut the leads near the body and twist / solder to the old. This isn't the prettiest way , but i recommend don't disturb the larger joints with multiple connections . No "cold" solders , heat the work first . Observe polarity on the electrolytics , the arrow points to negative rail. If you put these in backwards you'll get a nasty surprise. Don't lose focus , do this when there's no chance you'll be interrupted . Overhandling (sp?) can be A problem , you'll see what I mean. Go slow. Be careful when there's power , the trans is probably 250v and definitely noticeable.
A pair of medical forcepts will be your best friend.
Don't try to run it with any of the 80 year old caps, if they short ( and they will, not debatable) it could ruin things like expensive transformers and whatnot .
The speaker should be fine unless it's obviously damaged or punched out. You need to use the original due to its field coil rather than a permanent magnet
This is basically the non technical approach, there's a phone book worth of retro science in these things but it's not really necessary to know , you're just replacing components.
http://www.tuberadios.com/capacitors/
I usually get the Radio working first before I do any cosmetics. For the AC cord replacement I just buy an extension cord and cut off the end , or if you want to use that antique plug , it probably just uses screws to attach. The grill cloths are available , maybe not an exact match but no one will know . It's probably glued and sandwiched like you said, to keep it tight. You'll have to figure out how to get it off . The one thing i always say to myself about these things is- if it went in , it will come out.
http://www.radiodaze.com/grille-cloth/
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All very good advice. I use 3M Super 77 spray adhesive to attach the grille cloth to the wood backing. I mist it a little with water to loosen it up and then gently stretch it as much as possible to prevent it from gapping later. Hope the project goes well!
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Chris,
Some guys use a 0-125 volt Variac to gradually apply power while monitoring the line current.
If the current starts to go off the chart then power is removed before something gets fried.
In any case, at least change out the electrolytic caps and replace the shabby line cord before
powering it up.
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Yes, that's the best way ! However ,The smoke/ funky old burning rubber smell that doesnt go away for days is much more exciting! I would isolate sensitive computer stuff during these tests just as a precaution.
Seriously though- he's right . can't stress safety enough, you'll probably violate good sense at several points though. 8)
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Yes, these old timers were designed for 110 to 115ac, not the 125 found in a lot of places today. Then again, I figure most of the resistors go high when they move around in these relics, so a bit more tension in the wire may be what they need. I run a variac set to 115 for the R388 and R390A to keep them happy and pampered.
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I'll second or third the recommendation to use a variac and slowly increase the voltage when you do apply AC power to it. As Josh mentioned, these older radios were designed with 110 VAC in mind, and most mains AC voltage today is closer to 120 (that can depend though). Probably best to power it up on its own circuit when you finish doing the restoration work.
Always nice to see an old radio get another life :D