The Stovebolt Site Forums The Shop Area The Electrical Bay tube radio repair

Did a quick search and only came up with one hit from back in 02. radio was working untill swithced balace. it let out a squill and all we get now is a hummmmmmmm. any ideas? know of somebody that will do repair that one can trust

In the link section under electricial there is a link called Vintage Radio Restorations. Click on this link and check it out, it might be what you are looking for.

thank you for the tip will try a couple sits i found and see if we can get this tube one fixed or go to one of those origanl looking am/fm units might be money ahead

a sure way to get yerself killed or badly shocked is to mess with a tube type radio. unlike transistor radios the tube type have pretty good sized capacitors (those things store electricity, and i mean a bunch of it, and for a pretty long time). in the old days it was no uncommon for the news to report that a person was killed by working on their car radio.

ya know, the advise about the antique radio shopp seems pretty good to me.

be careful, we need all the good bolters we can get!

dakota, look at www.turnswith.com they recondidtion classic car radios or make them over not cheap but worth a look. hope this helps. ron

dakota, sorry didn't check spelling. www.turnswitch.com

One rule to use when working on any high voltage electronic circuit:
Keep one hand behind your back when poking around. Fatal electrical jolts pass through the heart. This is usually by the current passing in one arm and out the other. When the path to ground through your body is through your legs you are less likely to go into fibrillation or cardiac arrest from an electrical shock.

Electric heart defibrillators work by passing a current through your heart from a capacitor charged up to a high voltage. Your tube radio works on high voltage electric fields provided by capacitors charged up to high voltage. If in doubt, short out all capacitors using a resistor connected to alligator clips with one hand before working on the circuit. An alternate way is to connect an old analog voltmeter across the capacitor and wait until the meter reads zero before proceeding. The input impedance to the meter is low enough to make the cap discharge.

The odds of being killled by a car radio is very unlikely. Their is neither a lot of voltage (275V) nor a lot of joules in a car radio capacitor. The vibrator does produce voltage peaks in the 1kV range (which is why there is a small cap on the secondary) but at 275V after the rectifier, the danger is very small. Just be careful. A tube radio is usually easy to fix since it has few active devices. Do not mess with the alignment. Common culprits are tubes and caps. Caps often get leaky with age. Sometimes, the electric field wiil reform the oxide layer in electrolytic caps, sometimes not. Get a radio repair manual and a catalog from Antique Electronics Supply. Where are you at in South Dakota??

I rebuilt two original radios for a 1957 pickup. I would have to say that if you don't know much about tube radios, then it may not make sense to try repairing them. Some of the components are hard to get & are easy to destroy. It cost me about $75 dollars in components for each radio (I got the solid-state multi-vibrator & completely re-tubed them in addition to replacement of the electrolytics). Unfortunately most AM stations that I could get were talk radio. So I bought a custom auto-sound radio that looks similar to the real thing & bolts right in. From what I can tell they are no more than a professionaly restored original and I can get FM stations. Most people can't even tell. I keep the other two radios on shelf (just in case).

thank you for the come back on this radio, putting in a order for the fac. looking replacement with am/fm. will send this one off to get fixed latter, just in case the boy wants to put the old one in. thank you again. had forgot about the chance of getting the fingers lite up.

mike j/dakota

I would have to agree that the danger with these old AD radios is small. I got a nip off mine a few weeks ago and it made me pay attention! The dangerous ones are the old console radios, with much higher B+ supplies and large capacitors.

Talk radio: I think that it is a modern curse of the AM band!!

i don't profess to be an electrical engineer. i have no theories involving flux capacitors or the relativity. i simply remember when i was about 7 years old and coming home from school and seeing my neighbor laying on the floor of his buick. i didn't know then he was dead. my dad explained it to me after the ambulance and coroners wagon left.

maybe the guy had a bad heart, i dunno. maybe it wasn't the shock but the surprise of the shock that killed the guy. again i have no idea. i DO think a measure of caution is in order, and to minimize any form of danger ain't exactly responsible. then there's the fact that unless you don't know how to fix something, and have no idea how it works, then about all a person can do is mess it up worse, and make the repair more expensive, or make it not repairable. personally, when the coe is finished, it won't be bone stock, but i understand those who are building museum quality trucks. they are almost a form of art that can be driven. to that end, consider how hard it might be to find an exact replacement that is in good working order for your truck, and ask yourself if it's worth messing with, or using for your next science fair exibit.

do what ya want. it is after all, yours. personally i will send my electronic stuff to someone who is trained. that would not be me. as uneducated and ignorant as i am, i have figured that out. the image of the dead guy is still an image i can recall 46 years later.

strange really, considering i can't remember to pick up a gallon of milk on the way home from work.

You are right, koolkar. I do profess to be an electrical engineer.
From evidence that I have found on the web, it takes as little as 1 Joule of energy through the heart to send it into fibrillation. How much is a Joule of energy? It is the discharge of one 26.4 microfarad capacitor charged up to 275 volts. (E=C*V^2/2). Now, if the radio was powered up, or there were more than one capacitor, the energy delivered could be significantly higher. B+ supplies usually have over 100 microfarads of capacitance available. That makes about 3.8 joules, which is enough to burn you pretty good and jolt your heart pretty badly.

Yes, commercial defibrillators typically provide 200J+ of energy, but they provide that much to make sure they work the first time, and they also have to overcome the resistance of the skin. If you accidentally [censored] yourself or your hands are wet you can easily overcome the skin resistance and then the impedance of your body is very low.

While very unlikely it is possible to get killed by working on tube car radios. Sure, if you have it out on the bench and it has been shut off for a while the caps probably leak down enough to not be dangerous, but if you have the radio in the car and maybe turned on and your hands are wet or sweaty and you grab the wrong thing and your heart is a bit weak you could die. Please err on the side of safety!

I have been repairing and building tube equipment for 10+ years. It is like any other hobby: if you are careless, unlucky, or just plain stupid, you can get hurt. You know not to stick your fingers in turning fan blade don't you??? Same concept here. If you read up and understand what you are doing, you'll be fine.

4onthefloor
I have never seen a piece of 50s era consumer electronics with +100uF B+ caps (400V+) but I've never messed with any TVs. The technology for cost effective large electrolytics didn't exist back then. I have heard anecdotes that the 300-400V is more dangerous; supposedly more likely to fibrilate your heart.

Jason,
yes the old TVs can give you quite a whopper. I used to work on the old tube jobs and a number of time I got too close to the high voltage. They were designed to be fairly high impedance so that they couldn't really pump much into you for long. However, I did get the odd brown burn hole in my skin from those incidents.

The old console radios had B+ supplies well over 500V and they were bad to come into contact with.

All that said, for me to revive one of these old radios from an otherwise junk state, still gives me quite a thrill. I find it to be a relaxing and fascinating hobby.

so, i suppose, there ya have it. if ya wanna work on yer radio, then by all means do it. just be careful and know that there is a possibility you could get a nasty shock. i can't imagine anybody not at least hooking the radio up to a bench power supply and testing the thing to see what the problem might be. hence, the word of caution.

that's all it was. a word of caution. not meant to cause controversy, or differences of opinion. the point is, 1 person that i knew,did in fact die while messing with an am tube type radio. what did it, i ain't sure, and don't wanna find out.

what i DO want if for all of us to expire at a very ripe old age.

like i wrote on a run report several years ago. "cause of death: too much birthday cake"

I've had a nasty shock from grounding a capacitor in a modern stereo through my hand. Of course, I've also had far worse from straight 110v wall current (don't go there). Like anything else, be careful - just like not working on a vehicle until it is properly supported on jack stands.

KK, I plan to expire at a ripe old age - in 26+ years I've had enough close scrapes to convince me that it just isn't my time to bite the big one.

So, all this discussion and nobody has ever had a good jolt from the spark plug wires? That one will wake you up too!

KoolCar,
I know how impressions stick. When I was young, I saw them reviving a guy that almost drowned, at the beach. Now that scene has stayed with me since. I really enjoy swimming but I absolutely do not break any of the swimming rules.