The radio is made in Japan (looks to be early '60's style) AM-FM 7 tubes: 35C5, 17EW8(2),12BA6(2),12BE6,12AV6. Model is AF-610W (La Treviata) and appears to have been imported by Seaway Trading & Electronics Ltd., Toronto.
It has suffered some major power supply damage (blown .05 mfd cap., toasted power leads, burned resistors and I am unable to determine the values of some of the components. Any guesses as to manufacturer please?
Thanks
::An old local recluse-type visited me yesterday with a radio underarm to see if I could get it running once again. This chap is very eccentric and is a pack-rat type who treasures every "find." I told him I would look at it and see what can be done - would really like to repair it for him even though it's not a high-line set. All the info I can provide is as follows (manufacturer's label missing off bottom.)
::
::The radio is made in Japan (looks to be early '60's style) AM-FM 7 tubes: 35C5, 17EW8(2),12BA6(2),12BE6,12AV6. Model is AF-610W (La Treviata) and appears to have been imported by Seaway Trading & Electronics Ltd., Toronto.
::
::It has suffered some major power supply damage (blown .05 mfd cap., toasted power leads, burned resistors and I am unable to determine the values of some of the components. Any guesses as to manufacturer please?
::
::Thanks
:This is pretty much a 5 tube American special, there are a lot of those out there, Admiral made some. It sounds like the rectifier shorted or the line cap (.05) shorted. Just look around Nostalgia for the basic all american minature tube 5. Admiral, westinghouse, and others made them.
:
:
:::An old local recluse-type visited me yesterday with a radio underarm to see if I could get it running once again. This chap is very eccentric and is a pack-rat type who treasures every "find." I told him I would look at it and see what can be done - would really like to repair it for him even though it's not a high-line set. All the info I can provide is as follows (manufacturer's label missing off bottom.)
:::
:::The radio is made in Japan (looks to be early '60's style) AM-FM 7 tubes: 35C5, 17EW8(2),12BA6(2),12BE6,12AV6. Model is AF-610W (La Treviata) and appears to have been imported by Seaway Trading & Electronics Ltd., Toronto.
:::
:::It has suffered some major power supply damage (blown .05 mfd cap., toasted power leads, burned resistors and I am unable to determine the values of some of the components. Any guesses as to manufacturer please?
:::
:::Thanks
Dave
When testing any of the above diodes, they should be disconnected from the set. At minimum, one lead should be disconnected, and in cases where you worry that you may not reconnect it properly, this will have to suffice. The side that is connected to the line cord should receive your negative meter lead, and the side facing the electrolytic condensers and filtering network should receive your positive lead. Test as mentioned above. Replacements of the most modern form are found at Radio Shack. The forward and reverse voltage must be high (at least 250 volts). They cost no more than two dollars.
Seeing as the condenser across the line cord is blown up severely, this would be my first place to look for trouble. This condenser is not polarized, and should never be of the polarized variety. It is a regular condenser like any other small condenser within the radio. It serves to remove some interferance that may enter the radio through the line cord, such as noises from vacuum cleaners and improperly designed kitchen mixers. The Sunbeam Mixmaster of the 1940s has its own filtering network built right into the mixer, so you can listen to noiseless AM radio while making cookies. How nice!
I can't imagine any resistors being connected before this condenser to the line cord. If there are resistors blown, it is more likely that the rectifier diode is shorted, or the electrolytics have shorted. None of these would affect the line cord condenser in any way, and if both sections have failed, consider it coincidence. It is possible that, on rare occasion, a radio has been designed with resistors of extremely low rating (10-40 ohms), and of high wattage (1 watt or more), that are connected to the line cord prior to the line cord condenser. They would have acted as a sort of fuse, should something go wrong in the radio. I have seen this perhaps once in a radio from the 1960s. If so, then it is possible that they did in fact blow due to the line cord condenser.
What did the man say happened when he used the radio? Has he owned it for some time, or did he find it in the trash, rummage sale, etc.? Do the tubes light? Perhaps, with the line cord condenser being blown, the radio put on quite a light show for the original owner, and then blew the household fuse. This would cause someone to discard the radio. With resistors blown, however, it sounds more like trouble in the rectifier section. As electrolytics commonly go bad, and solid state diodes follow right behind electrolytics for high failure rates, I'd really check this section out. You didn't mention a rectifier tube, so I'd hunt hard for some sort of solid state diode in any of the three forms listed above. If you tell all of us where the resistors that have blown connect, it will give all of us an idea of the trouble, and also we can throw some common values at you as to what the resistors should be. AC-DC sets all work with the same voltages (110 volts), and go from there. Most of us know what common voltages to expect at say the plate of the output tube (35C5, which runs from 90 to 110, depending on radio design), and there-on, so if you give us all an idea of what resistor blew, and where, we can throw some stuff back at you so you can get a similar resistor in its place. Those radios are flexible, so if you're off by a few thousand ohms in the power section, life won't be too bad, and the radio will probably perform quite well as is. Other places, such as ballast resistors in the filament or pilot light section are the same values in all radios of that nature with .15 ampere tubes and certain tube counts, so we can give you right-on values. Same with resistors like the cathode bias resistor on say the 35C5 tube. It's almost always 150 ohms, with the grid bias around 470k ohms. If one isn't used (rare), then you likely have a grid bias of a few million ohms, etc.
Hope you find the trouble,
Thomas
::With the 17EW8, sounds like it may have FM. Perhaps solid state discriminator? Otherwise the power supply troubles, as listed below, are like any other AC-DC set. It wasn't uncommon, by this time, to find solid state power supplies, discriminator diodes, and perhaps even a transistor in the FM circuit. As stated, a shorted solid state diode (semi-common trouble) would cause major havvoc, as would a shorted line cord condenser (.05 mfd).
::
:::This is pretty much a 5 tube American special, there are a lot of those out there, Admiral made some. It sounds like the rectifier shorted or the line cap (.05) shorted. Just look around Nostalgia for the basic all american minature tube 5. Admiral, westinghouse, and others made them.
:::
:::
:::::An old local recluse-type visited me yesterday with a radio underarm to see if I could get it running once again. This chap is very eccentric and is a pack-rat type who treasures every "find." I told him I would look at it and see what can be done - would really like to repair it for him even though it's not a high-line set. All the info I can provide is as follows (manufacturer's label missing off bottom.)
:::::
:::::The radio is made in Japan (looks to be early '60's style) AM-FM 7 tubes: 35C5, 17EW8(2),12BA6(2),12BE6,12AV6. Model is AF-610W (La Treviata) and appears to have been imported by Seaway Trading & Electronics Ltd., Toronto.
:::::
:::::It has suffered some major power supply damage (blown .05 mfd cap., toasted power leads, burned resistors and I am unable to determine the values of some of the components. Any guesses as to manufacturer please?
:::::
:::::Thanks
:Thank you for the info. gentlemen... I cannot see any solid-state devices in the unit. I would presume the .05mfd. line cord cap. to be 400 - 600 volts? Would this be a polarized cap? I have only part of one end which indicates the value - everything else is obliterated.
:Thanks again.
:
:Dave
Thomas
:Well, the radio has to have a solid state rectifier, as you do not name any rectifier tubes in your line-up. 17EW8 is a dual triode (probably used in the FM oscillator section), 12BA6 is an RF pentode, 12BE6 will be your AM oscillator/mixer heptode (7 grids), 12AV6 will be your first audio amplifier and AM detector (dual diode/triode), and finally, the 35C5 will be your beam pentode audio output tube. No rectifier tube mentioned in the above such as 35W4 (a common 7 pin minature). A small object that looks like a stack of plates with a bolt (or rivvet) running through the center, with a terminal at each end (and on rare occasion, other terminals) will be your solid state rectifier. In this case, an early version, utilizing a selenium chemical on the plates, known as a selenium diode or rectifier. These commonly short with age. With your meter set at its most sensitive resistance checking position, there should be current flowing in one direction, but none in the other. There should be absolutely no leakage in the other direction. On occasion a leakage of several tens of thousands of ohms or higher is acceptable, but generally this causes hum, can destroy electrolytics, and eventually will develop into a much more severe short. If this device is not found, the diode will be in a much smaller and more modern form, either as a small metal cylinder about the size of a 1/2 watt resistor, with one end flanged into a sort of plate, or the second, much more modern form, molded much like a resistor. This last form will often be black. On either form, you may see the diode symbol ->|- (as best as I can type it), and on the most modern form, there will likely be a line around the circumfrence of one end, denoting the cathode side. If you cannot see any solid state devices on the radio, and it is on a chassis, the diodes are likely mounted within the chassis. This is common proceedure, with the selenium being the exception. The selenium diode will be found both on top of and within the chassis by about a 50/50 chance. However, if the radio is built on a printed circuit board and no solid state devices are seen, then I don't know what to say, as you havn't mentioned any rectifier tube for your radio.
:
:When testing any of the above diodes, they should be disconnected from the set. At minimum, one lead should be disconnected, and in cases where you worry that you may not reconnect it properly, this will have to suffice. The side that is connected to the line cord should receive your negative meter lead, and the side facing the electrolytic condensers and filtering network should receive your positive lead. Test as mentioned above. Replacements of the most modern form are found at Radio Shack. The forward and reverse voltage must be high (at least 250 volts). They cost no more than two dollars.
:
:Seeing as the condenser across the line cord is blown up severely, this would be my first place to look for trouble. This condenser is not polarized, and should never be of the polarized variety. It is a regular condenser like any other small condenser within the radio. It serves to remove some interferance that may enter the radio through the line cord, such as noises from vacuum cleaners and improperly designed kitchen mixers. The Sunbeam Mixmaster of the 1940s has its own filtering network built right into the mixer, so you can listen to noiseless AM radio while making cookies. How nice!
:
:I can't imagine any resistors being connected before this condenser to the line cord. If there are resistors blown, it is more likely that the rectifier diode is shorted, or the electrolytics have shorted. None of these would affect the line cord condenser in any way, and if both sections have failed, consider it coincidence. It is possible that, on rare occasion, a radio has been designed with resistors of extremely low rating (10-40 ohms), and of high wattage (1 watt or more), that are connected to the line cord prior to the line cord condenser. They would have acted as a sort of fuse, should something go wrong in the radio. I have seen this perhaps once in a radio from the 1960s. If so, then it is possible that they did in fact blow due to the line cord condenser.
:
:What did the man say happened when he used the radio? Has he owned it for some time, or did he find it in the trash, rummage sale, etc.? Do the tubes light? Perhaps, with the line cord condenser being blown, the radio put on quite a light show for the original owner, and then blew the household fuse. This would cause someone to discard the radio. With resistors blown, however, it sounds more like trouble in the rectifier section. As electrolytics commonly go bad, and solid state diodes follow right behind electrolytics for high failure rates, I'd really check this section out. You didn't mention a rectifier tube, so I'd hunt hard for some sort of solid state diode in any of the three forms listed above. If you tell all of us where the resistors that have blown connect, it will give all of us an idea of the trouble, and also we can throw some common values at you as to what the resistors should be. AC-DC sets all work with the same voltages (110 volts), and go from there. Most of us know what common voltages to expect at say the plate of the output tube (35C5, which runs from 90 to 110, depending on radio design), and there-on, so if you give us all an idea of what resistor blew, and where, we can throw some stuff back at you so you can get a similar resistor in its place. Those radios are flexible, so if you're off by a few thousand ohms in the power section, life won't be too bad, and the radio will probably perform quite well as is. Other places, such as ballast resistors in the filament or pilot light section are the same values in all radios of that nature with .15 ampere tubes and certain tube counts, so we can give you right-on values. Same with resistors like the cathode bias resistor on say the 35C5 tube. It's almost always 150 ohms, with the grid bias around 470k ohms. If one isn't used (rare), then you likely have a grid bias of a few million ohms, etc.
:
:Hope you find the trouble,
:
:Thomas
:
:::With the 17EW8, sounds like it may have FM. Perhaps solid state discriminator? Otherwise the power supply troubles, as listed below, are like any other AC-DC set. It wasn't uncommon, by this time, to find solid state power supplies, discriminator diodes, and perhaps even a transistor in the FM circuit. As stated, a shorted solid state diode (semi-common trouble) would cause major havvoc, as would a shorted line cord condenser (.05 mfd).
:::
::::This is pretty much a 5 tube American special, there are a lot of those out there, Admiral made some. It sounds like the rectifier shorted or the line cap (.05) shorted. Just look around Nostalgia for the basic all american minature tube 5. Admiral, westinghouse, and others made them.
::::
::::
::::::An old local recluse-type visited me yesterday with a radio underarm to see if I could get it running once again. This chap is very eccentric and is a pack-rat type who treasures every "find." I told him I would look at it and see what can be done - would really like to repair it for him even though it's not a high-line set. All the info I can provide is as follows (manufacturer's label missing off bottom.)
::::::
::::::The radio is made in Japan (looks to be early '60's style) AM-FM 7 tubes: 35C5, 17EW8(2),12BA6(2),12BE6,12AV6. Model is AF-610W (La Treviata) and appears to have been imported by Seaway Trading & Electronics Ltd., Toronto.
::::::
::::::It has suffered some major power supply damage (blown .05 mfd cap., toasted power leads, burned resistors and I am unable to determine the values of some of the components. Any guesses as to manufacturer please?
::::::
::::::Thanks
::Thank you for the info. gentlemen... I cannot see any solid-state devices in the unit. I would presume the .05mfd. line cord cap. to be 400 - 600 volts? Would this be a polarized cap? I have only part of one end which indicates the value - everything else is obliterated.
::Thanks again.
::
::Dave
Regards,
Dave
The power supply section consists of a 7-lug terminal strip with a few components hanging off it - I have got the set to fire up ok without burning up but there is no sound of any type. On the terminal strip there are two identical components which appear to be similar to FM inductance coils but of course they are not if they are on the power supply side. They have a grey plastic insulation over them and are about the size of a 1 watt resistor. I have no idea what these things are - they show continuity on the ohmmeter so they are not open at least. Any idea what these may be?
As an aside; I spoke with the old chap who brought the set over. He related that he had received it from a fellow back in the late 1960's in lieu of cash for some yard work he had done. He claims he took it home, plugged it in and with the exception of unexpected power outages, it has never been turned off! He does not remember anything happening to it but the trouble could have occurred while he was sleeping. I have no reason to doubt the old fellow's word (he has a reputation for iron-clad honesty) and I am fascinated that for something that appears to be so cheaply made, it has only packed it in just recently.
Thomas
:::Also, I forgot something else about that .05 mfd condenser. If resistors are blown, it is also possible that the condenser is connected in the power supply from the rectifier to B- (other side of line cord). This was also done, though less commonly, to eliminate radio interferance. If the condenser blew here, it would blow resistors in the B supply connected before the solid state diode, or from the solid state diode to the condenser. It would also likely blow the diode. If the diode was rugged enough, it may also toast the line cord. A third method, also used on occasion, has the condenser connected across the diode itself, meaning that the condenser is connected to each side of the diode. If the condenser would short then, it would be the same as shorting out the diode, and would send AC directly to the electrolytics, would destroy resistors in the path, and also possibly the electrolytics themselves. So, this said, give great detail as to where all blown components are connected.
:::
:::Thomas
:::
:::
:::
:::
::::Well, the radio has to have a solid state rectifier, as you do not name any rectifier tubes in your line-up. 17EW8 is a dual triode (probably used in the FM oscillator section), 12BA6 is an RF pentode, 12BE6 will be your AM oscillator/mixer heptode (7 grids), 12AV6 will be your first audio amplifier and AM detector (dual diode/triode), and finally, the 35C5 will be your beam pentode audio output tube. No rectifier tube mentioned in the above such as 35W4 (a common 7 pin minature). A small object that looks like a stack of plates with a bolt (or rivvet) running through the center, with a terminal at each end (and on rare occasion, other terminals) will be your solid state rectifier. In this case, an early version, utilizing a selenium chemical on the plates, known as a selenium diode or rectifier. These commonly short with age. With your meter set at its most sensitive resistance checking position, there should be current flowing in one direction, but none in the other. There should be absolutely no leakage in the other direction. On occasion a leakage of several tens of thousands of ohms or higher is acceptable, but generally this causes hum, can destroy electrolytics, and eventually will develop into a much more severe short. If this device is not found, the diode will be in a much smaller and more modern form, either as a small metal cylinder about the size of a 1/2 watt resistor, with one end flanged into a sort of plate, or the second, much more modern form, molded much like a resistor. This last form will often be black. On either form, you may see the diode symbol ->|- (as best as I can type it), and on the most modern form, there will likely be a line around the circumfrence of one end, denoting the cathode side. If you cannot see any solid state devices on the radio, and it is on a chassis, the diodes are likely mounted within the chassis. This is common proceedure, with the selenium being the exception. The selenium diode will be found both on top of and within the chassis by about a 50/50 chance. However, if the radio is built on a printed circuit board and no solid state devices are seen, then I don't know what to say, as you havn't mentioned any rectifier tube for your radio.
::::
::::When testing any of the above diodes, they should be disconnected from the set. At minimum, one lead should be disconnected, and in cases where you worry that you may not reconnect it properly, this will have to suffice. The side that is connected to the line cord should receive your negative meter lead, and the side facing the electrolytic condensers and filtering network should receive your positive lead. Test as mentioned above. Replacements of the most modern form are found at Radio Shack. The forward and reverse voltage must be high (at least 250 volts). They cost no more than two dollars.
::::
::::Seeing as the condenser across the line cord is blown up severely, this would be my first place to look for trouble. This condenser is not polarized, and should never be of the polarized variety. It is a regular condenser like any other small condenser within the radio. It serves to remove some interferance that may enter the radio through the line cord, such as noises from vacuum cleaners and improperly designed kitchen mixers. The Sunbeam Mixmaster of the 1940s has its own filtering network built right into the mixer, so you can listen to noiseless AM radio while making cookies. How nice!
::::
::::I can't imagine any resistors being connected before this condenser to the line cord. If there are resistors blown, it is more likely that the rectifier diode is shorted, or the electrolytics have shorted. None of these would affect the line cord condenser in any way, and if both sections have failed, consider it coincidence. It is possible that, on rare occasion, a radio has been designed with resistors of extremely low rating (10-40 ohms), and of high wattage (1 watt or more), that are connected to the line cord prior to the line cord condenser. They would have acted as a sort of fuse, should something go wrong in the radio. I have seen this perhaps once in a radio from the 1960s. If so, then it is possible that they did in fact blow due to the line cord condenser.
::::
::::What did the man say happened when he used the radio? Has he owned it for some time, or did he find it in the trash, rummage sale, etc.? Do the tubes light? Perhaps, with the line cord condenser being blown, the radio put on quite a light show for the original owner, and then blew the household fuse. This would cause someone to discard the radio. With resistors blown, however, it sounds more like trouble in the rectifier section. As electrolytics commonly go bad, and solid state diodes follow right behind electrolytics for high failure rates, I'd really check this section out. You didn't mention a rectifier tube, so I'd hunt hard for some sort of solid state diode in any of the three forms listed above. If you tell all of us where the resistors that have blown connect, it will give all of us an idea of the trouble, and also we can throw some common values at you as to what the resistors should be. AC-DC sets all work with the same voltages (110 volts), and go from there. Most of us know what common voltages to expect at say the plate of the output tube (35C5, which runs from 90 to 110, depending on radio design), and there-on, so if you give us all an idea of what resistor blew, and where, we can throw some stuff back at you so you can get a similar resistor in its place. Those radios are flexible, so if you're off by a few thousand ohms in the power section, life won't be too bad, and the radio will probably perform quite well as is. Other places, such as ballast resistors in the filament or pilot light section are the same values in all radios of that nature with .15 ampere tubes and certain tube counts, so we can give you right-on values. Same with resistors like the cathode bias resistor on say the 35C5 tube. It's almost always 150 ohms, with the grid bias around 470k ohms. If one isn't used (rare), then you likely have a grid bias of a few million ohms, etc.
::::
::::Hope you find the trouble,
::::
::::Thomas
::::
::::::With the 17EW8, sounds like it may have FM. Perhaps solid state discriminator? Otherwise the power supply troubles, as listed below, are like any other AC-DC set. It wasn't uncommon, by this time, to find solid state power supplies, discriminator diodes, and perhaps even a transistor in the FM circuit. As stated, a shorted solid state diode (semi-common trouble) would cause major havvoc, as would a shorted line cord condenser (.05 mfd).
::::::
:::::::This is pretty much a 5 tube American special, there are a lot of those out there, Admiral made some. It sounds like the rectifier shorted or the line cap (.05) shorted. Just look around Nostalgia for the basic all american minature tube 5. Admiral, westinghouse, and others made them.
:::::::
:::::::
:::::::::An old local recluse-type visited me yesterday with a radio underarm to see if I could get it running once again. This chap is very eccentric and is a pack-rat type who treasures every "find." I told him I would look at it and see what can be done - would really like to repair it for him even though it's not a high-line set. All the info I can provide is as follows (manufacturer's label missing off bottom.)
:::::::::
:::::::::The radio is made in Japan (looks to be early '60's style) AM-FM 7 tubes: 35C5, 17EW8(2),12BA6(2),12BE6,12AV6. Model is AF-610W (La Treviata) and appears to have been imported by Seaway Trading & Electronics Ltd., Toronto.
:::::::::
:::::::::It has suffered some major power supply damage (blown .05 mfd cap., toasted power leads, burned resistors and I am unable to determine the values of some of the components. Any guesses as to manufacturer please?
:::::::::
:::::::::Thanks
:::::Thank you for the info. gentlemen... I cannot see any solid-state devices in the unit. I would presume the .05mfd. line cord cap. to be 400 - 600 volts? Would this be a polarized cap? I have only part of one end which indicates the value - everything else is obliterated.
:::::Thanks again.
:::::
:::::Dave
::Thank you kindly for taking the considerable time in passing along all the information. I'll go over the underside of the set again later tomorrow (there are no printed circuit boards; all hard-wired and tube) and yes, I'm slipping in my old age - I assumed the 35C5 could have been a recifier! Obviously, there is a solid-state device somewhere in the mix and I'll track it down and pull the electrolytic as well. I gave the old chap an old Emerson I had kicking around so he would have something to listen to while I took a peek at his. I'll let you know what happens.
::
::Regards,
::Dave
:Hi again
:Managed to find the diode (round disk unit almost identical to the disk capacitor which is tied across its leads!). Speaking of disk caps., they must have had a firesale on them when this thing was built - they are all over the place, especially .0047mfd. units.
:
:The power supply section consists of a 7-lug terminal strip with a few components hanging off it - I have got the set to fire up ok without burning up but there is no sound of any type. On the terminal strip there are two identical components which appear to be similar to FM inductance coils but of course they are not if they are on the power supply side. They have a grey plastic insulation over them and are about the size of a 1 watt resistor. I have no idea what these things are - they show continuity on the ohmmeter so they are not open at least. Any idea what these may be?
:As an aside; I spoke with the old chap who brought the set over. He related that he had received it from a fellow back in the late 1960's in lieu of cash for some yard work he had done. He claims he took it home, plugged it in and with the exception of unexpected power outages, it has never been turned off! He does not remember anything happening to it but the trouble could have occurred while he was sleeping. I have no reason to doubt the old fellow's word (he has a reputation for iron-clad honesty) and I am fascinated that for something that appears to be so cheaply made, it has only packed it in just recently.
Thomas
:WOW! Can't believe he left it on like that! The coils you find on the AC cord could either be filters, or, they could be the method used in linking the FM antenna to the line cord. See if there are any other wires coming off these coils that may run to the FM RF input circuit. If there are, then there may be more than one coil within those coils, allowing the line cord to electromagnetically connect to the FM circuit like a transformer. Many FM radios have the antenna electrically connected to the line cord either through a condenser, or a coil. They may also have the option of disconnecting this, and connecting an antenna in back. Left connected, the line cord, and the wiring in the home, does a rather fine job of bringing in signals. Sometimes, when a station is coming in poorly, you can move the line cord and improve the reception. You could do this for AM as well, but since AM is amplitude modulation, you'd pick up all the amplitude modulations in the wiring in your home.
:
:Thomas
:
::::Also, I forgot something else about that .05 mfd condenser. If resistors are blown, it is also possible that the condenser is connected in the power supply from the rectifier to B- (other side of line cord). This was also done, though less commonly, to eliminate radio interferance. If the condenser blew here, it would blow resistors in the B supply connected before the solid state diode, or from the solid state diode to the condenser. It would also likely blow the diode. If the diode was rugged enough, it may also toast the line cord. A third method, also used on occasion, has the condenser connected across the diode itself, meaning that the condenser is connected to each side of the diode. If the condenser would short then, it would be the same as shorting out the diode, and would send AC directly to the electrolytics, would destroy resistors in the path, and also possibly the electrolytics themselves. So, this said, give great detail as to where all blown components are connected.
::::
::::Thomas
::::
::::
::::
::::
:::::Well, the radio has to have a solid state rectifier, as you do not name any rectifier tubes in your line-up. 17EW8 is a dual triode (probably used in the FM oscillator section), 12BA6 is an RF pentode, 12BE6 will be your AM oscillator/mixer heptode (7 grids), 12AV6 will be your first audio amplifier and AM detector (dual diode/triode), and finally, the 35C5 will be your beam pentode audio output tube. No rectifier tube mentioned in the above such as 35W4 (a common 7 pin minature). A small object that looks like a stack of plates with a bolt (or rivvet) running through the center, with a terminal at each end (and on rare occasion, other terminals) will be your solid state rectifier. In this case, an early version, utilizing a selenium chemical on the plates, known as a selenium diode or rectifier. These commonly short with age. With your meter set at its most sensitive resistance checking position, there should be current flowing in one direction, but none in the other. There should be absolutely no leakage in the other direction. On occasion a leakage of several tens of thousands of ohms or higher is acceptable, but generally this causes hum, can destroy electrolytics, and eventually will develop into a much more severe short. If this device is not found, the diode will be in a much smaller and more modern form, either as a small metal cylinder about the size of a 1/2 watt resistor, with one end flanged into a sort of plate, or the second, much more modern form, molded much like a resistor. This last form will often be black. On either form, you may see the diode symbol ->|- (as best as I can type it), and on the most modern form, there will likely be a line around the circumfrence of one end, denoting the cathode side. If you cannot see any solid state devices on the radio, and it is on a chassis, the diodes are likely mounted within the chassis. This is common proceedure, with the selenium being the exception. The selenium diode will be found both on top of and within the chassis by about a 50/50 chance. However, if the radio is built on a printed circuit board and no solid state devices are seen, then I don't know what to say, as you havn't mentioned any rectifier tube for your radio.
:::::
:::::When testing any of the above diodes, they should be disconnected from the set. At minimum, one lead should be disconnected, and in cases where you worry that you may not reconnect it properly, this will have to suffice. The side that is connected to the line cord should receive your negative meter lead, and the side facing the electrolytic condensers and filtering network should receive your positive lead. Test as mentioned above. Replacements of the most modern form are found at Radio Shack. The forward and reverse voltage must be high (at least 250 volts). They cost no more than two dollars.
:::::
:::::Seeing as the condenser across the line cord is blown up severely, this would be my first place to look for trouble. This condenser is not polarized, and should never be of the polarized variety. It is a regular condenser like any other small condenser within the radio. It serves to remove some interferance that may enter the radio through the line cord, such as noises from vacuum cleaners and improperly designed kitchen mixers. The Sunbeam Mixmaster of the 1940s has its own filtering network built right into the mixer, so you can listen to noiseless AM radio while making cookies. How nice!
:::::
:::::I can't imagine any resistors being connected before this condenser to the line cord. If there are resistors blown, it is more likely that the rectifier diode is shorted, or the electrolytics have shorted. None of these would affect the line cord condenser in any way, and if both sections have failed, consider it coincidence. It is possible that, on rare occasion, a radio has been designed with resistors of extremely low rating (10-40 ohms), and of high wattage (1 watt or more), that are connected to the line cord prior to the line cord condenser. They would have acted as a sort of fuse, should something go wrong in the radio. I have seen this perhaps once in a radio from the 1960s. If so, then it is possible that they did in fact blow due to the line cord condenser.
:::::
:::::What did the man say happened when he used the radio? Has he owned it for some time, or did he find it in the trash, rummage sale, etc.? Do the tubes light? Perhaps, with the line cord condenser being blown, the radio put on quite a light show for the original owner, and then blew the household fuse. This would cause someone to discard the radio. With resistors blown, however, it sounds more like trouble in the rectifier section. As electrolytics commonly go bad, and solid state diodes follow right behind electrolytics for high failure rates, I'd really check this section out. You didn't mention a rectifier tube, so I'd hunt hard for some sort of solid state diode in any of the three forms listed above. If you tell all of us where the resistors that have blown connect, it will give all of us an idea of the trouble, and also we can throw some common values at you as to what the resistors should be. AC-DC sets all work with the same voltages (110 volts), and go from there. Most of us know what common voltages to expect at say the plate of the output tube (35C5, which runs from 90 to 110, depending on radio design), and there-on, so if you give us all an idea of what resistor blew, and where, we can throw some stuff back at you so you can get a similar resistor in its place. Those radios are flexible, so if you're off by a few thousand ohms in the power section, life won't be too bad, and the radio will probably perform quite well as is. Other places, such as ballast resistors in the filament or pilot light section are the same values in all radios of that nature with .15 ampere tubes and certain tube counts, so we can give you right-on values. Same with resistors like the cathode bias resistor on say the 35C5 tube. It's almost always 150 ohms, with the grid bias around 470k ohms. If one isn't used (rare), then you likely have a grid bias of a few million ohms, etc.
:::::
:::::Hope you find the trouble,
:::::
:::::Thomas
:::::
:::::::With the 17EW8, sounds like it may have FM. Perhaps solid state discriminator? Otherwise the power supply troubles, as listed below, are like any other AC-DC set. It wasn't uncommon, by this time, to find solid state power supplies, discriminator diodes, and perhaps even a transistor in the FM circuit. As stated, a shorted solid state diode (semi-common trouble) would cause major havvoc, as would a shorted line cord condenser (.05 mfd).
:::::::
::::::::This is pretty much a 5 tube American special, there are a lot of those out there, Admiral made some. It sounds like the rectifier shorted or the line cap (.05) shorted. Just look around Nostalgia for the basic all american minature tube 5. Admiral, westinghouse, and others made them.
::::::::
::::::::
::::::::::An old local recluse-type visited me yesterday with a radio underarm to see if I could get it running once again. This chap is very eccentric and is a pack-rat type who treasures every "find." I told him I would look at it and see what can be done - would really like to repair it for him even though it's not a high-line set. All the info I can provide is as follows (manufacturer's label missing off bottom.)
::::::::::
::::::::::The radio is made in Japan (looks to be early '60's style) AM-FM 7 tubes: 35C5, 17EW8(2),12BA6(2),12BE6,12AV6. Model is AF-610W (La Treviata) and appears to have been imported by Seaway Trading & Electronics Ltd., Toronto.
::::::::::
::::::::::It has suffered some major power supply damage (blown .05 mfd cap., toasted power leads, burned resistors and I am unable to determine the values of some of the components. Any guesses as to manufacturer please?
::::::::::
::::::::::Thanks
::::::Thank you for the info. gentlemen... I cannot see any solid-state devices in the unit. I would presume the .05mfd. line cord cap. to be 400 - 600 volts? Would this be a polarized cap? I have only part of one end which indicates the value - everything else is obliterated.
::::::Thanks again.
::::::
::::::Dave
:::Thank you kindly for taking the considerable time in passing along all the information. I'll go over the underside of the set again later tomorrow (there are no printed circuit boards; all hard-wired and tube) and yes, I'm slipping in my old age - I assumed the 35C5 could have been a recifier! Obviously, there is a solid-state device somewhere in the mix and I'll track it down and pull the electrolytic as well. I gave the old chap an old Emerson I had kicking around so he would have something to listen to while I took a peek at his. I'll let you know what happens.
:::
:::Regards,
:::Dave
::Hi again
::Managed to find the diode (round disk unit almost identical to the disk capacitor which is tied across its leads!). Speaking of disk caps., they must have had a firesale on them when this thing was built - they are all over the place, especially .0047mfd. units.
::
::The power supply section consists of a 7-lug terminal strip with a few components hanging off it - I have got the set to fire up ok without burning up but there is no sound of any type. On the terminal strip there are two identical components which appear to be similar to FM inductance coils but of course they are not if they are on the power supply side. They have a grey plastic insulation over them and are about the size of a 1 watt resistor. I have no idea what these things are - they show continuity on the ohmmeter so they are not open at least. Any idea what these may be?
::As an aside; I spoke with the old chap who brought the set over. He related that he had received it from a fellow back in the late 1960's in lieu of cash for some yard work he had done. He claims he took it home, plugged it in and with the exception of unexpected power outages, it has never been turned off! He does not remember anything happening to it but the trouble could have occurred while he was sleeping. I have no reason to doubt the old fellow's word (he has a reputation for iron-clad honesty) and I am fascinated that for something that appears to be so cheaply made, it has only packed it in just recently.
Thanks for the information Thomas. Yes, I said he was somewhat eccentric! You have spent a great deal of time with this and I appreciate it. I shall go through the set over the weekend for voltages,etc. although I have no schematic to compare to. The tubes, remaining caps (including the filter cap. surprisingly), resistors all checked out O.K.. If I can't get it running by then, I'll let him keep the Emerson (provided he does not want FM!!!) I just hate to give up on this stuff.
Thanks again.
Dave
I bet since the set worked fine before it blew, none of the circuitry in the RF sections is out of alignment. Since you do not mention any twin diode tubes (like a 6AL5, or some .15 ampere type), I think you'll find germanium diodes or something of the like for the discriminator circuit of the FM section. If you get the set to hum and the amplifier works, then there is a slight chance that these could be blown from any voltage surges. Not likely, though, because they are not even remotely connected to the power supply. Still, they are delicate. Since you say that the set does nothing on AM or FM, then I guess you have trouble in the power or audio sections. If you remember the old trick of connecting a phonograph pick-up to your radio, you can use this to hook a portable CD player to it (or tape player). Hook a .05 mfd condenser to the ground terminal of the volume control, and hook this to the shielded lead of the cord coming off your player, and hook another .05 mfd condenser to the extreme opposite terminal of the control. Hook this to the inner lead of the cord on your portable player. You should have a condenser connected to each extreme outer lead of the volume control. Then turn the CD player up high (like 8 or 9 if it has numbers from 1 to 10), and adjust the volume of the radio. See what you hear. If you hear clear, undistorted music, consider this section fine. If the music is distorted, this also may be caused by the CD player being turned up too far. Turn it down just a bit until the distortion goes away, and then try out the volume of the radio.....should be loud and pleasant. Any distortion found now can likely be traced to leaky bypass condensers from stage to stage.
Anyway, let me know about any blown components that are discolored beyond recognition. Perhaps I can come up with some values. Also, be sure that you hooked your new rectifier diode up properly. Test the set to see that positive and negative are in their proper places. If the polarity is wrong in the set, the tubes won't do anything, as current will not flow backwards through them. I assume that if the diode was in backwards, you'd blow both the diode and electrolytics, though, so you can be pretty sure that you have it in correctly. I am surprised that the electrolytics are fine after having the diode short, and after having the set run for this length of time. It is possible that when the old diode shorted out and blew up, it passed AC current to some small resistor down the line (like one that sends the lower voltages to the radio sections). If this resistor was connected to an electrolytic (which doesn't like AC current), the heavy current flow through the resistor could have blown it.
Thomas
::WOW! Can't believe he left it on like that! The coils you find on the AC cord could either be filters, or, they could be the method used in linking the FM antenna to the line cord. See if there are any other wires coming off these coils that may run to the FM RF input circuit. If there are, then there may be more than one coil within those coils, allowing the line cord to electromagnetically connect to the FM circuit like a transformer. Many FM radios have the antenna electrically connected to the line cord either through a condenser, or a coil. They may also have the option of disconnecting this, and connecting an antenna in back. Left connected, the line cord, and the wiring in the home, does a rather fine job of bringing in signals. Sometimes, when a station is coming in poorly, you can move the line cord and improve the reception. You could do this for AM as well, but since AM is amplitude modulation, you'd pick up all the amplitude modulations in the wiring in your home.
::
::Thomas
::
:::::Also, I forgot something else about that .05 mfd condenser. If resistors are blown, it is also possible that the condenser is connected in the power supply from the rectifier to B- (other side of line cord). This was also done, though less commonly, to eliminate radio interferance. If the condenser blew here, it would blow resistors in the B supply connected before the solid state diode, or from the solid state diode to the condenser. It would also likely blow the diode. If the diode was rugged enough, it may also toast the line cord. A third method, also used on occasion, has the condenser connected across the diode itself, meaning that the condenser is connected to each side of the diode. If the condenser would short then, it would be the same as shorting out the diode, and would send AC directly to the electrolytics, would destroy resistors in the path, and also possibly the electrolytics themselves. So, this said, give great detail as to where all blown components are connected.
:::::
:::::Thomas
:::::
:::::
:::::
:::::
::::::Well, the radio has to have a solid state rectifier, as you do not name any rectifier tubes in your line-up. 17EW8 is a dual triode (probably used in the FM oscillator section), 12BA6 is an RF pentode, 12BE6 will be your AM oscillator/mixer heptode (7 grids), 12AV6 will be your first audio amplifier and AM detector (dual diode/triode), and finally, the 35C5 will be your beam pentode audio output tube. No rectifier tube mentioned in the above such as 35W4 (a common 7 pin minature). A small object that looks like a stack of plates with a bolt (or rivvet) running through the center, with a terminal at each end (and on rare occasion, other terminals) will be your solid state rectifier. In this case, an early version, utilizing a selenium chemical on the plates, known as a selenium diode or rectifier. These commonly short with age. With your meter set at its most sensitive resistance checking position, there should be current flowing in one direction, but none in the other. There should be absolutely no leakage in the other direction. On occasion a leakage of several tens of thousands of ohms or higher is acceptable, but generally this causes hum, can destroy electrolytics, and eventually will develop into a much more severe short. If this device is not found, the diode will be in a much smaller and more modern form, either as a small metal cylinder about the size of a 1/2 watt resistor, with one end flanged into a sort of plate, or the second, much more modern form, molded much like a resistor. This last form will often be black. On either form, you may see the diode symbol ->|- (as best as I can type it), and on the most modern form, there will likely be a line around the circumfrence of one end, denoting the cathode side. If you cannot see any solid state devices on the radio, and it is on a chassis, the diodes are likely mounted within the chassis. This is common proceedure, with the selenium being the exception. The selenium diode will be found both on top of and within the chassis by about a 50/50 chance. However, if the radio is built on a printed circuit board and no solid state devices are seen, then I don't know what to say, as you havn't mentioned any rectifier tube for your radio.
::::::
::::::When testing any of the above diodes, they should be disconnected from the set. At minimum, one lead should be disconnected, and in cases where you worry that you may not reconnect it properly, this will have to suffice. The side that is connected to the line cord should receive your negative meter lead, and the side facing the electrolytic condensers and filtering network should receive your positive lead. Test as mentioned above. Replacements of the most modern form are found at Radio Shack. The forward and reverse voltage must be high (at least 250 volts). They cost no more than two dollars.
::::::
::::::Seeing as the condenser across the line cord is blown up severely, this would be my first place to look for trouble. This condenser is not polarized, and should never be of the polarized variety. It is a regular condenser like any other small condenser within the radio. It serves to remove some interferance that may enter the radio through the line cord, such as noises from vacuum cleaners and improperly designed kitchen mixers. The Sunbeam Mixmaster of the 1940s has its own filtering network built right into the mixer, so you can listen to noiseless AM radio while making cookies. How nice!
::::::
::::::I can't imagine any resistors being connected before this condenser to the line cord. If there are resistors blown, it is more likely that the rectifier diode is shorted, or the electrolytics have shorted. None of these would affect the line cord condenser in any way, and if both sections have failed, consider it coincidence. It is possible that, on rare occasion, a radio has been designed with resistors of extremely low rating (10-40 ohms), and of high wattage (1 watt or more), that are connected to the line cord prior to the line cord condenser. They would have acted as a sort of fuse, should something go wrong in the radio. I have seen this perhaps once in a radio from the 1960s. If so, then it is possible that they did in fact blow due to the line cord condenser.
::::::
::::::What did the man say happened when he used the radio? Has he owned it for some time, or did he find it in the trash, rummage sale, etc.? Do the tubes light? Perhaps, with the line cord condenser being blown, the radio put on quite a light show for the original owner, and then blew the household fuse. This would cause someone to discard the radio. With resistors blown, however, it sounds more like trouble in the rectifier section. As electrolytics commonly go bad, and solid state diodes follow right behind electrolytics for high failure rates, I'd really check this section out. You didn't mention a rectifier tube, so I'd hunt hard for some sort of solid state diode in any of the three forms listed above. If you tell all of us where the resistors that have blown connect, it will give all of us an idea of the trouble, and also we can throw some common values at you as to what the resistors should be. AC-DC sets all work with the same voltages (110 volts), and go from there. Most of us know what common voltages to expect at say the plate of the output tube (35C5, which runs from 90 to 110, depending on radio design), and there-on, so if you give us all an idea of what resistor blew, and where, we can throw some stuff back at you so you can get a similar resistor in its place. Those radios are flexible, so if you're off by a few thousand ohms in the power section, life won't be too bad, and the radio will probably perform quite well as is. Other places, such as ballast resistors in the filament or pilot light section are the same values in all radios of that nature with .15 ampere tubes and certain tube counts, so we can give you right-on values. Same with resistors like the cathode bias resistor on say the 35C5 tube. It's almost always 150 ohms, with the grid bias around 470k ohms. If one isn't used (rare), then you likely have a grid bias of a few million ohms, etc.
::::::
::::::Hope you find the trouble,
::::::
::::::Thomas
::::::
::::::::With the 17EW8, sounds like it may have FM. Perhaps solid state discriminator? Otherwise the power supply troubles, as listed below, are like any other AC-DC set. It wasn't uncommon, by this time, to find solid state power supplies, discriminator diodes, and perhaps even a transistor in the FM circuit. As stated, a shorted solid state diode (semi-common trouble) would cause major havvoc, as would a shorted line cord condenser (.05 mfd).
::::::::
:::::::::This is pretty much a 5 tube American special, there are a lot of those out there, Admiral made some. It sounds like the rectifier shorted or the line cap (.05) shorted. Just look around Nostalgia for the basic all american minature tube 5. Admiral, westinghouse, and others made them.
:::::::::
:::::::::
:::::::::::An old local recluse-type visited me yesterday with a radio underarm to see if I could get it running once again. This chap is very eccentric and is a pack-rat type who treasures every "find." I told him I would look at it and see what can be done - would really like to repair it for him even though it's not a high-line set. All the info I can provide is as follows (manufacturer's label missing off bottom.)
:::::::::::
:::::::::::The radio is made in Japan (looks to be early '60's style) AM-FM 7 tubes: 35C5, 17EW8(2),12BA6(2),12BE6,12AV6. Model is AF-610W (La Treviata) and appears to have been imported by Seaway Trading & Electronics Ltd., Toronto.
:::::::::::
:::::::::::It has suffered some major power supply damage (blown .05 mfd cap., toasted power leads, burned resistors and I am unable to determine the values of some of the components. Any guesses as to manufacturer please?
:::::::::::
:::::::::::Thanks
:::::::Thank you for the info. gentlemen... I cannot see any solid-state devices in the unit. I would presume the .05mfd. line cord cap. to be 400 - 600 volts? Would this be a polarized cap? I have only part of one end which indicates the value - everything else is obliterated.
:::::::Thanks again.
:::::::
:::::::Dave
::::Thank you kindly for taking the considerable time in passing along all the information. I'll go over the underside of the set again later tomorrow (there are no printed circuit boards; all hard-wired and tube) and yes, I'm slipping in my old age - I assumed the 35C5 could have been a recifier! Obviously, there is a solid-state device somewhere in the mix and I'll track it down and pull the electrolytic as well. I gave the old chap an old Emerson I had kicking around so he would have something to listen to while I took a peek at his. I'll let you know what happens.
::::
::::Regards,
::::Dave
:::Hi again
:::Managed to find the diode (round disk unit almost identical to the disk capacitor which is tied across its leads!). Speaking of disk caps., they must have had a firesale on them when this thing was built - they are all over the place, especially .0047mfd. units.
:::
:::The power supply section consists of a 7-lug terminal strip with a few components hanging off it - I have got the set to fire up ok without burning up but there is no sound of any type. On the terminal strip there are two identical components which appear to be similar to FM inductance coils but of course they are not if they are on the power supply side. They have a grey plastic insulation over them and are about the size of a 1 watt resistor. I have no idea what these things are - they show continuity on the ohmmeter so they are not open at least. Any idea what these may be?
:::As an aside; I spoke with the old chap who brought the set over. He related that he had received it from a fellow back in the late 1960's in lieu of cash for some yard work he had done. He claims he took it home, plugged it in and with the exception of unexpected power outages, it has never been turned off! He does not remember anything happening to it but the trouble could have occurred while he was sleeping. I have no reason to doubt the old fellow's word (he has a reputation for iron-clad honesty) and I am fascinated that for something that appears to be so cheaply made, it has only packed it in just recently.
:
:Thanks for the information Thomas. Yes, I said he was somewhat eccentric! You have spent a great deal of time with this and I appreciate it. I shall go through the set over the weekend for voltages,etc. although I have no schematic to compare to. The tubes, remaining caps (including the filter cap. surprisingly), resistors all checked out O.K.. If I can't get it running by then, I'll let him keep the Emerson (provided he does not want FM!!!) I just hate to give up on this stuff.
:Thanks again.
:Dave
Thanks again for all your helpful information Thomas. A donation to this site is forthcoming.
Dave
That's odd that it overloads on both AM and FM. Perhaps one of the RF tubes is not receiving enough B+? Usually FM does not use AM's AVC circuit, as it has its own limiter stage. If the AVC condenser was leaky, that'd cause the AM to overload. If any of the tubes in the RF section have a cathode bias resistor, and perhaps also a bypass condenser, I'd look here for trouble (drifted resistor, open/shorted condenser). Make sure all B+ resistors to these stages are at proper values (not drifted higher), and make sure that all electrolytics in these stages are in A+ condition (not weak or leaky). Look for open screen grid resistors if any are present. If one band overloaded and not the other, I'd say look to the AVC or limiter circuits, or the discriminator/ratio detector circuit.
Hope all works out well! Good that you got it running!
Thomas
:Just a note to let you know that I have the set up and running - found a bad pin in a tube socket! Tube was lit but not conducting. Now that audio is present, local stations are OK but when external antenna is connected, front-end overload occurs on both AM & FM.
:
:Thanks again for all your helpful information Thomas. A donation to this site is forthcoming.
:Dave