I was very young in the late 1960s and about that time about half of the 1940 and 1950 radios began to hum that's how I remembered most of them. My dad took a DeVry electronics home course and I was always watching him repair those plus TVs and record players for people. I also remember my mom talking about a young woman getting killed reaching for the radio while in the bathroom it was in the newspaper way back when. Poor girl what a horrible death. She made sure that I knew electrical safety and not to be grounded and to wear shoes and not to take it outside or especially where there are major grounded appliances or near water. My dad showed me the path that electricity takes to ground and not to touch the metal parts. The youth today is lucky
People would sometimes got shocked from equipment such as radios, so eventually polarized outlets were introduced. Even though the practice of "hot chasis" was long ago outlawed, and the equipment being out of widespread use, the old hack of polarized outlets remains. Although it is still frowned upon to switch the neutral.
my experience with ac has been that if you touch the "hot" side of an ac line you don't even need to complete the circuit to get a shock, the capacitance of the human body does an excellent job of giving you one anyway as the voltage pulses from 0 to about 170 (peak), charging you up and then discharging as the voltage increases, decreases and reverses direction. I don't have an isolation transformer, so I always check my chassis with a meter or neon tester
Greetings: This appears to be a Sears Silvertone model 8020 AM-FM radio. Usually that existing switch can be removed from the pot without too much work (the click will leave with the switch).
hot chassis design.. when I was a kid I had a record player from the 1960s, it was tube and I would get a nasty shock when I would touch the tonearm while standing bare foot on a concrete floor in the basement. I'm wondering if that was the issue with it?
I have a power transformer in a 1950 year AM/FM set by Silvertone . Model number 18. It was one of the last ones before they went to Selenium rectifiers which were cheaper. They don't put " isolation" transformers in radios. Power transformers were used to get line voltage AC in into two or more AC voltage supplies. One for the tube heaters and dial lamp(s) if used and the other to get the B+ supply which must be further rectified.
I checked out the plate voltage of many tubes normally used in radios and I found that the tubes can work comfortably with an increase voltage of up to 70 volts in the low range. In fact the higher the voltage the lower the plate current. That means that some tubes can work at higher voltages with no problem. So the resistor in series with the diodes need not be there. Also some people say that helps prevent an inrush of current. So what bad will that do? i have been building tube amps for the last 50 years using diodes in the rectifier stage and the inrush only charges the caps the real current is achieved after the tube heaters are warm and a signal is injected. Please explain what this inrush thing is so bad to me. Regards N6YOC
I didn't know that they made an AM/FM model in that cabinet, the AM ones seem fairly common. Is the dial leans cracked or are those just deep scratches? More fun and games undoing the work of fly by night service persons.
My Zenith hi-fi AM/FM receiver from 1957 is a series-string set with a single silicon rectifier (you wouldn't know it was there unless you knew where to look). I got FM working by replacing one of the hybrid components and two of the tubes. It still doesn't sound quite right...
Ive done a couple of selenium to silicon conversions, mostly out of fear of the dreaded selenium eol smoke. People always mention how bad its supposed to be although Ive never had it happen yet.
Nice set. Will it receive an upgrade with an AC safety cap across the line? Similarly, a friend I knew would put a .01 disc across the power switch for spark arrest, and maybe one across diodes at times. Yes, If its worth doing, it's worth doing right. Nice IF cans in this Arvin!
Were you ever able to track down the problem with the FM side? I have one like it and the FM isn't working. I can not seem to find the trouble. I suspect there is a common problem.
Hi there. Most FM tube radios by now have stopped working because FM is more demanding on the FM oscillator circuit and takes more plate current than AM. I had a Philco model 48-1283 AM FM PHONO console that I restored and the AM worked but not FM. I found that the main b plus was measuring about 142 volts when it should have been 340 volts. The culprit was a weak rectifier tube. The loctal socket was so badly burned that I just used a couple of 1N4007 diodes soldered underneath and that brought it up to a strong 360 volts and FM worked good. FM tuner tubes need good emissions and healthy plate voltage. I hate to say it but RF transistors are better for FM but tubes are much better for AM
I like your videos, attitude towards old and new electronics, and your voice. But this time I disagree to the way you conducted the repair: I would have kept the beautiful Selenium rectifier for the historic look and just connect the silicon diode underneath the chassis.
Hi Phononut, A while back I bought a real nice Crosley 56TC, wood body tube radio and would like to restore the electronics, power cord is bad, and, who knows what else. It looks to be all original, and, appears to have not been worked on. The chassis is fully enclosed and looks to be riveted together. Would you have any suggestions on what I should do? Drill out the rivets looks to be the only way inside. Thankyou for any help you can offer. The radio is the 'American Overseas', the chassis has "1525" stamped on it. Take care, C.
Had a weak SEEEEasonal rectum-fire! LOL! That's typical of those. I always replace seleniums with a diode/resistor combo when I see one as if they aren't already weak, they will go weak eventually so save trouble down the road & replace that SEAsonal witha die-ode-ee-eye-A! we'll have to see episode 2 for more! Can't wait to see if he gets the FM going! LOL!
Sears has some weird things in their radios. Instead of a 35W4 rectifier tube which has a heater tap for a # 47 6.3V dial lamp, they have a selenium rectifier with a 7W 120V night light bulb for a dial light Weird!!!!
The selenium rectifier is typical for AM/FM sets, because they need the 35 volts saved for the or 4 tubes added for FM. I never quite understood the point of a $5 transformer to power a light, though; why not just use a resister or a 120 volt light?
I know what you mean about the failure of a Selenium rectifier stack. I had one that was only giving a B+ of 120V, when it should have been 200. Yet another died violently and smelled like a clogged sewer.
Everyone always talks about Isolation Transformer and I agree that are must have, but has anyone priced one that can handle 5 amps. Holy crap talk about price fixing.
Greetings: For an isolation transformer, look for a big used 120/240 switchable transformer that has two 120vac windings. Use the second winding as your isolation winding. It will only handle 1/2 the power as when two windings were in parallel. Any 5vac or 6.3vac filament windings can be wired out of phase with the 120vac input winding to lower the output winding AC resulting from today's elevated mains levels. Also, when replacing the selenium rectifier, a non-polarized capacitor can be used ahead of any diodes to drop the rectified DC level as a substitute for the power wasting dropper resistor. Find a good TH-cam capacitor dropper circuit for the calculations. A motor run or starting cap OR microwave oven cap is non-polarized. I think about 33mfd is a good starting point then reduce until the B+ is right. I'll look for the Calc formula. Place a 1meg resistor across any dropper diode for safety. Meanwhile, the tube heater string should not be affected by any dropper cap placed ahead of the silicon diode and filters. As 1N4007's are cheap, I would use 4 in a bridge to convert from 60 Hz ripple to 120 Hz ripple to extend the life of the filter caps. Capacitor droppers are very popular in 240vac countries. A separate dropper cap can be added to reduce the elevated mains AC from 125vac to 110vac if you wish.
Hi Phononut, A while back I bought a real nice Crosley 56TC, wood body tube radio and would like to restore the electronics, power cord is bad, and, who knows what else. It looks to be all original, and, appears to have not been worked on. The chassis is fully enclosed and looks to be riveted together. Would you have any suggestions on what I should do? Drill out the rivets looks to be the only way inside. Thankyou for any help you can offer. The radio is the 'American Overseas', the chassis has "1525" stamped on it. Take care, C.
I was very young in the late 1960s and about that time about half of the 1940 and 1950 radios began to hum that's how I remembered most of them. My dad took a DeVry electronics home course and I was always watching him repair those plus TVs and record players for people. I also remember my mom talking about a young woman getting killed reaching for the radio while in the bathroom it was in the newspaper way back when. Poor girl what a horrible death. She made sure that I knew electrical safety and not to be grounded and to wear shoes and not to take it outside or especially where there are major grounded appliances or near water. My dad showed me the path that electricity takes to ground and not to touch the metal parts. The youth today is lucky
Your Smart Parents brought you up well!
People would sometimes got shocked from equipment such as radios, so eventually polarized outlets were introduced. Even though the practice of "hot chasis" was long ago outlawed, and the equipment being out of widespread use, the old hack of polarized outlets remains. Although it is still frowned upon to switch the neutral.
my experience with ac has been that if you touch the "hot" side of an ac line you don't even need to complete the circuit to get a shock, the capacitance of the human body does an excellent job of giving you one anyway as the voltage pulses from 0 to about 170 (peak), charging you up and then discharging as the voltage increases, decreases and reverses direction. I don't have an isolation transformer, so I always check my chassis with a meter or neon tester
Greetings:
This appears to be a Sears Silvertone model 8020 AM-FM radio.
Usually that existing switch can be removed from the pot without too much work (the click will leave with the switch).
Dang, that's a great looking set. I may buy one of those.
I would love you to do a recone of that speaker video,
I have to say that I love the use of a night light bulb for the dial lamp!
Looks like a 7c7 lamp (7 watt)
Looks like a mfr's label on chassis rear. Any model or chassis I'd there?
That's the biggest dial lamp I've ever seen. Looks like a C9 Christmas light.
Busy work bench ,nice save on that radio
hot chassis design.. when I was a kid I had a record player from the 1960s, it was tube and I would get a nasty shock when I would touch the tonearm while standing bare foot on a concrete floor in the basement. I'm wondering if that was the issue with it?
cowtippingrocks In all likelihood, yes!
You can tell Selenium rectifiers are less efficient, because of the cooling fins. Resistance can cause heat.
5:25 But why didn't they use AC power isolation xformers in these larger, and presumably higher end, receiver sets?
I have a power transformer in a 1950 year AM/FM set by Silvertone . Model number 18. It was one of the last ones
before they went to Selenium rectifiers which were cheaper. They don't put " isolation" transformers in radios.
Power transformers were used to get line voltage AC in into two or more AC voltage supplies. One for the tube
heaters and dial lamp(s) if used and the other to get the B+ supply which must be further rectified.
I checked out the plate voltage of many tubes normally used in radios and I found that the tubes can work comfortably with an increase voltage of up to 70 volts in the low range. In fact the higher the voltage the lower the plate current. That means that some tubes can work at higher voltages with no problem. So the resistor in series with the diodes need not be there. Also some people say that helps prevent an inrush of current. So what bad will that do? i have been building tube amps for the last 50 years using diodes in the rectifier stage and the inrush only charges the caps the real current is achieved after the tube heaters are warm and a signal is injected. Please explain what this inrush thing is so bad to me.
Regards N6YOC
I didn't know that they made an AM/FM model in that cabinet, the AM ones seem fairly common. Is the dial leans cracked or are those just deep scratches? More fun and games undoing the work of fly by night service persons.
Hi, have you posted part two? Can't seem to find it. VERY interested!
I don't see it listed either.
A Selenium Rectifier in a large tabletop radio, how very unusual!
Can a bad selenium rectifier cause a set to work for a while and then suddenly die until you switch it off for a while?
Sangamo Little Chiefs, the green and tan plastic covered caps, those are like little firecrackers when they decide to go.
My Zenith hi-fi AM/FM receiver from 1957 is a series-string set with a single silicon rectifier (you wouldn't know it was there unless you knew where to look). I got FM working by replacing one of the hybrid components and two of the tubes. It still doesn't sound quite right...
why are there two transformers on that chassis? is one output and one choke, or is this a stereo unit?
One is an audio output transformer and the other is a filter choke in the power supply.
Ive done a couple of selenium to silicon conversions, mostly out of fear of the dreaded selenium eol smoke. People always mention how bad its supposed to be although Ive never had it happen yet.
Nice set. Will it receive an upgrade with an AC safety cap across the line? Similarly, a friend I knew would put a .01 disc across the power switch for spark arrest, and maybe one across diodes at times. Yes, If its worth doing, it's worth doing right.
Nice IF cans in this Arvin!
I enjoyed this video.
Were you ever able to track down the problem with the FM side? I have one like it and the FM isn't working. I can not seem to find the trouble. I suspect there is a common problem.
Hi there. Most FM tube radios by now have stopped working because FM is more demanding on the FM oscillator circuit and takes more plate current than AM. I had a Philco model 48-1283 AM FM PHONO console that I restored and the AM worked but not FM. I found that the main b plus was measuring about 142 volts when it should have been 340 volts. The culprit was a weak rectifier tube. The loctal socket was so badly burned that I just used a couple of 1N4007 diodes soldered underneath and that brought it up to a strong 360 volts and FM worked good. FM tuner tubes need good emissions and healthy plate voltage. I hate to say it but RF transistors are better for FM but tubes are much better for AM
I like your videos, attitude towards old and new electronics, and your voice. But this time I disagree to the way you conducted the repair: I would have kept the beautiful Selenium rectifier for the historic look and just connect the silicon diode underneath the chassis.
.......verey nice find!
Hi Phononut, A while back I bought a real nice Crosley 56TC, wood body tube radio and would like to restore the electronics, power cord is bad, and, who knows what else. It looks to be all original, and, appears to have not been worked on. The chassis is fully enclosed and looks to be riveted together. Would you have any suggestions on what I should do? Drill out the rivets looks to be the only way inside. Thankyou for any help you can offer. The radio is the 'American Overseas', the chassis has "1525" stamped on it. Take care, C.
Thank enjoyed this Video Much
Had a weak SEEEEasonal rectum-fire! LOL! That's typical of those. I always replace seleniums with a diode/resistor combo when I see one as if they aren't already weak, they will go weak eventually so save trouble down the road & replace that SEAsonal witha die-ode-ee-eye-A! we'll have to see episode 2 for more! Can't wait to see if he gets the FM going! LOL!
Sears has some weird things in their radios. Instead of a 35W4 rectifier tube which has a heater tap for a # 47 6.3V dial lamp, they have a selenium rectifier with a 7W 120V night light bulb for a dial light Weird!!!!
The selenium rectifier is typical for AM/FM sets, because they need the 35 volts saved for the or 4 tubes added for FM. I never quite understood the point of a $5 transformer to power a light, though; why not just use a resister or a 120 volt light?
I know what you mean about the failure of a Selenium rectifier stack.
I had one that was only giving a B+ of 120V, when it should have been 200.
Yet another died violently and smelled like a clogged sewer.
Everyone always talks about Isolation Transformer and I agree that are must have, but has anyone priced one that can handle 5 amps. Holy crap talk about price fixing.
Greetings:
For an isolation transformer, look for a big used 120/240 switchable transformer that has two 120vac windings. Use the second winding as your isolation winding. It will only handle 1/2 the power as when two windings were in parallel. Any 5vac or 6.3vac filament windings can be wired out of phase with the 120vac input winding to lower the output winding AC resulting from today's elevated mains levels.
Also, when replacing the selenium rectifier, a non-polarized capacitor can be used ahead of any diodes to drop the rectified DC level as a substitute for the power wasting dropper resistor. Find a good TH-cam capacitor dropper circuit for the calculations. A motor run or starting cap OR microwave oven cap is non-polarized. I think about 33mfd is a good starting point then reduce until the B+ is right. I'll look for the Calc formula. Place a 1meg resistor across any dropper diode for safety. Meanwhile, the tube heater string should not be affected by any dropper cap placed ahead of the silicon diode and filters. As 1N4007's are cheap, I would use 4 in a bridge to convert from 60 Hz ripple to 120 Hz ripple to extend the life of the filter caps. Capacitor droppers are very popular in 240vac countries.
A separate dropper cap can be added to reduce the elevated mains AC from 125vac to 110vac if you wish.
AM works? Thats me sorted ;) i use a ipod loaded with 1960's radio shows.
FM tube tuners work good with high plate voltage aww just use a diode straight. I bet ya got weak FM tuner tubes 😁
This unit belongs to Hank Hill.
looks like robbie the robot
i hate when they mess with um
You speak too Fast! you need to give us time to understand what you esplannin.
Hi Phononut, A while back I bought a real nice Crosley 56TC, wood body tube radio and would like to restore the electronics, power cord is bad, and, who knows what else. It looks to be all original, and, appears to have not been worked on. The chassis is fully enclosed and looks to be riveted together. Would you have any suggestions on what I should do? Drill out the rivets looks to be the only way inside. Thankyou for any help you can offer. The radio is the 'American Overseas', the chassis has "1525" stamped on it. Take care, C.