Jeff
Poston
:Hi,
:I'm restoring a Zenith H615 I inherited and I'm wondering about the audio amp tube I found in it (a 50L6). After reviewing the schematics (for a G615, since I couldn't find H615 schematics), it appears the audio amp should be a 35L6. This radio hasn't been used much in the last 20 years, and I don't think it's been serviced in at least 35 years, which tells me that the 50L6 has been in there a long time. Is there a problem substituting a 50L6 for a 35L6? Would it need to draw the extra 15 volts to operate properly? Also, I'm replacing the electrolytic caps that appear to have been replaced at least once a long time ago. The G615 schematic calls for 40/80 multiple, however the old replacements are separate 30 and 50 mfd caps. I know it's a no-no to replace caps with smaller values, but what kind of damage could be caused by using the inferior valued caps?
:As always, any help is greatly appreciated!
:
:Jeff
:Hi Jeff,
:The Zenith H615 (Chassis 6G05) is covered in Sams Photofact 140-14 (dated 7/51). It indicates this radio uses a 35L6 output tube, and either a 35Y4 or 35W4 rectifier tube. Filter caps are specified as 80mfd/40mfd @ 150v. I suspect the earlier cap replacement was done by a shop who happened to have those values in stock. Probably worked OK, as there is a wide tolerance range on electrolytic caps. No damage would be done to the radio with slightly smaller mfd caps, provided voltage rating was adequate. But filtering might not be as good, hence some hum could result. For replacement I would try to get a little closer to the original cap values.
:
:Poston
:
:
::Hi,
::I'm restoring a Zenith H615 I inherited and I'm wondering about the audio amp tube I found in it (a 50L6). After reviewing the schematics (for a G615, since I couldn't find H615 schematics), it appears the audio amp should be a 35L6. This radio hasn't been used much in the last 20 years, and I don't think it's been serviced in at least 35 years, which tells me that the 50L6 has been in there a long time. Is there a problem substituting a 50L6 for a 35L6? Would it need to draw the extra 15 volts to operate properly? Also, I'm replacing the electrolytic caps that appear to have been replaced at least once a long time ago. The G615 schematic calls for 40/80 multiple, however the old replacements are separate 30 and 50 mfd caps. I know it's a no-no to replace caps with smaller values, but what kind of damage could be caused by using the inferior valued caps?
::As always, any help is greatly appreciated!
::
::Jeff
For your tube question, there is no problem substituting a 50L6 for a 35L6. They both have the same .15 amperage draw. The tubes will glow somewhat dimmer, but it will be almost unnoticeable. When you add more resistance to a series string, the total current draw will be LESS, not more. Strain on the tubes will be less--filaments. I have done this substitution many times when I didn't have the 35 volt tube available, with wonderful results. Audio output will not be noticeably different, if it is affected at all. The tubes may take a very slight amount more to warm up. It can be done as a permanent replacement with no bad results. I heard a couple of times that operating the cathode at a colder temperature causes it to not build up enough electrons, and therefore fail sooner. The majority of things I've heard, though, about coated cathodes, say that it is better to operate them slightly cooler if you can, which will make them last longer due to slightly lower electron emission. My personal results favor this second statement. If you question the tube layout of your radio, the total voltage should equal about 121 volts, as it usually does. Typically a 6 tube radio will have 4 12 volt tubes, and 2 35 volt tubes. On occasion, such as my Zenith Cobra phonograph (table model), you will find 2 12 volt tubes, 2 6 volt tubes, 1 35 volt tube (rectifier), and 1 50 volt tube (audio output). Otherwise, if it is a five tube model, it is typical to find 3 12 volt tubes, 1 35 volt tube, and 1 50 volt tube. In a 5 tube set, the 50 volt tube should never be substituted with a 35 volt tube, unless a ballast resistor is added, which hardly seems worth the time it takes to find another 50 volt tube. When substituting tubes in a series string, not only should the voltage be the same or slightly higher, but the amperage should be exactly the same. In sets mentioned above, this amperage is typically .15 amps. The 6 volt tubes in the above sets are also .15 amps, which is rare to find, as most 6 volt tubes are .3 amps. A .3 amp tube of the 6 volt variety will not light in the above type of radio, and if a large voltage tube (50L6) is replaced with a same voltage but higher amperage (.3) tube, not only will it not light, but it is likely to blow the other tubes. An example would be the 25L6 tube. This tube draws .3 amps, where-as the 35L6 and 50L6 draw .15 amperes. The 25L6 is not manufactured with a .15 ampere filament, and therefore cannot be strung with the .15 ampere tubes. If this tube is found in a series strung radio, the radio will use an older arrangement. The rectifier will also be a 25 volt tube (such as the 25Z5), and the rest of the tubes will all be 6 volt tubes of the .3 ampere variety. To finish things off so that the total voltage is around 121, there will be a ballast resistor of some type, usually in the form of a big resistor, a resistance element in the line cord, or a ballast tube.
Thomas
Thomas
:Thanks for the info. Any problem using a 50L6 instead of a 35L6?
:
::Hi Jeff,
::The Zenith H615 (Chassis 6G05) is covered in Sams Photofact 140-14 (dated 7/51). It indicates this radio uses a 35L6 output tube, and either a 35Y4 or 35W4 rectifier tube. Filter caps are specified as 80mfd/40mfd @ 150v. I suspect the earlier cap replacement was done by a shop who happened to have those values in stock. Probably worked OK, as there is a wide tolerance range on electrolytic caps. No damage would be done to the radio with slightly smaller mfd caps, provided voltage rating was adequate. But filtering might not be as good, hence some hum could result. For replacement I would try to get a little closer to the original cap values.
::
::Poston
::
::
:::Hi,
:::I'm restoring a Zenith H615 I inherited and I'm wondering about the audio amp tube I found in it (a 50L6). After reviewing the schematics (for a G615, since I couldn't find H615 schematics), it appears the audio amp should be a 35L6. This radio hasn't been used much in the last 20 years, and I don't think it's been serviced in at least 35 years, which tells me that the 50L6 has been in there a long time. Is there a problem substituting a 50L6 for a 35L6? Would it need to draw the extra 15 volts to operate properly? Also, I'm replacing the electrolytic caps that appear to have been replaced at least once a long time ago. The G615 schematic calls for 40/80 multiple, however the old replacements are separate 30 and 50 mfd caps. I know it's a no-no to replace caps with smaller values, but what kind of damage could be caused by using the inferior valued caps?
:::As always, any help is greatly appreciated!
:::
:::Jeff
Thanks for the info and especially the explanation on tube voltages & amp values. I wasn't aware of the amp value issue in these tube substitutions. I get smarter every time I read the traffic in this forum...
Jeff
:Hi Jeff,
:
:For your tube question, there is no problem substituting a 50L6 for a 35L6. They both have the same .15 amperage draw. The tubes will glow somewhat dimmer, but it will be almost unnoticeable. When you add more resistance to a series string, the total current draw will be LESS, not more. Strain on the tubes will be less--filaments. I have done this substitution many times when I didn't have the 35 volt tube available, with wonderful results. Audio output will not be noticeably different, if it is affected at all. The tubes may take a very slight amount more to warm up. It can be done as a permanent replacement with no bad results. I heard a couple of times that operating the cathode at a colder temperature causes it to not build up enough electrons, and therefore fail sooner. The majority of things I've heard, though, about coated cathodes, say that it is better to operate them slightly cooler if you can, which will make them last longer due to slightly lower electron emission. My personal results favor this second statement. If you question the tube layout of your radio, the total voltage should equal about 121 volts, as it usually does. Typically a 6 tube radio will have 4 12 volt tubes, and 2 35 volt tubes. On occasion, such as my Zenith Cobra phonograph (table model), you will find 2 12 volt tubes, 2 6 volt tubes, 1 35 volt tube (rectifier), and 1 50 volt tube (audio output). Otherwise, if it is a five tube model, it is typical to find 3 12 volt tubes, 1 35 volt tube, and 1 50 volt tube. In a 5 tube set, the 50 volt tube should never be substituted with a 35 volt tube, unless a ballast resistor is added, which hardly seems worth the time it takes to find another 50 volt tube. When substituting tubes in a series string, not only should the voltage be the same or slightly higher, but the amperage should be exactly the same. In sets mentioned above, this amperage is typically .15 amps. The 6 volt tubes in the above sets are also .15 amps, which is rare to find, as most 6 volt tubes are .3 amps. A .3 amp tube of the 6 volt variety will not light in the above type of radio, and if a large voltage tube (50L6) is replaced with a same voltage but higher amperage (.3) tube, not only will it not light, but it is likely to blow the other tubes. An example would be the 25L6 tube. This tube draws .3 amps, where-as the 35L6 and 50L6 draw .15 amperes. The 25L6 is not manufactured with a .15 ampere filament, and therefore cannot be strung with the .15 ampere tubes. If this tube is found in a series strung radio, the radio will use an older arrangement. The rectifier will also be a 25 volt tube (such as the 25Z5), and the rest of the tubes will all be 6 volt tubes of the .3 ampere variety. To finish things off so that the total voltage is around 121, there will be a ballast resistor of some type, usually in the form of a big resistor, a resistance element in the line cord, or a ballast tube.
:
:Thomas
:
:Thomas
:
::Thanks for the info. Any problem using a 50L6 instead of a 35L6?
::
:::Hi Jeff,
:::The Zenith H615 (Chassis 6G05) is covered in Sams Photofact 140-14 (dated 7/51). It indicates this radio uses a 35L6 output tube, and either a 35Y4 or 35W4 rectifier tube. Filter caps are specified as 80mfd/40mfd @ 150v. I suspect the earlier cap replacement was done by a shop who happened to have those values in stock. Probably worked OK, as there is a wide tolerance range on electrolytic caps. No damage would be done to the radio with slightly smaller mfd caps, provided voltage rating was adequate. But filtering might not be as good, hence some hum could result. For replacement I would try to get a little closer to the original cap values.
:::
:::Poston
:::
:::
::::Hi,
::::I'm restoring a Zenith H615 I inherited and I'm wondering about the audio amp tube I found in it (a 50L6). After reviewing the schematics (for a G615, since I couldn't find H615 schematics), it appears the audio amp should be a 35L6. This radio hasn't been used much in the last 20 years, and I don't think it's been serviced in at least 35 years, which tells me that the 50L6 has been in there a long time. Is there a problem substituting a 50L6 for a 35L6? Would it need to draw the extra 15 volts to operate properly? Also, I'm replacing the electrolytic caps that appear to have been replaced at least once a long time ago. The G615 schematic calls for 40/80 multiple, however the old replacements are separate 30 and 50 mfd caps. I know it's a no-no to replace caps with smaller values, but what kind of damage could be caused by using the inferior valued caps?
::::As always, any help is greatly appreciated!
::::
::::Jeff
Take care,
Thomas
:Thomas,
:
:Thanks for the info and especially the explanation on tube voltages & amp values. I wasn't aware of the amp value issue in these tube substitutions. I get smarter every time I read the traffic in this forum...
:
:Jeff
:
::Hi Jeff,
::
::For your tube question, there is no problem substituting a 50L6 for a 35L6. They both have the same .15 amperage draw. The tubes will glow somewhat dimmer, but it will be almost unnoticeable. When you add more resistance to a series string, the total current draw will be LESS, not more. Strain on the tubes will be less--filaments. I have done this substitution many times when I didn't have the 35 volt tube available, with wonderful results. Audio output will not be noticeably different, if it is affected at all. The tubes may take a very slight amount more to warm up. It can be done as a permanent replacement with no bad results. I heard a couple of times that operating the cathode at a colder temperature causes it to not build up enough electrons, and therefore fail sooner. The majority of things I've heard, though, about coated cathodes, say that it is better to operate them slightly cooler if you can, which will make them last longer due to slightly lower electron emission. My personal results favor this second statement. If you question the tube layout of your radio, the total voltage should equal about 121 volts, as it usually does. Typically a 6 tube radio will have 4 12 volt tubes, and 2 35 volt tubes. On occasion, such as my Zenith Cobra phonograph (table model), you will find 2 12 volt tubes, 2 6 volt tubes, 1 35 volt tube (rectifier), and 1 50 volt tube (audio output). Otherwise, if it is a five tube model, it is typical to find 3 12 volt tubes, 1 35 volt tube, and 1 50 volt tube. In a 5 tube set, the 50 volt tube should never be substituted with a 35 volt tube, unless a ballast resistor is added, which hardly seems worth the time it takes to find another 50 volt tube. When substituting tubes in a series string, not only should the voltage be the same or slightly higher, but the amperage should be exactly the same. In sets mentioned above, this amperage is typically .15 amps. The 6 volt tubes in the above sets are also .15 amps, which is rare to find, as most 6 volt tubes are .3 amps. A .3 amp tube of the 6 volt variety will not light in the above type of radio, and if a large voltage tube (50L6) is replaced with a same voltage but higher amperage (.3) tube, not only will it not light, but it is likely to blow the other tubes. An example would be the 25L6 tube. This tube draws .3 amps, where-as the 35L6 and 50L6 draw .15 amperes. The 25L6 is not manufactured with a .15 ampere filament, and therefore cannot be strung with the .15 ampere tubes. If this tube is found in a series strung radio, the radio will use an older arrangement. The rectifier will also be a 25 volt tube (such as the 25Z5), and the rest of the tubes will all be 6 volt tubes of the .3 ampere variety. To finish things off so that the total voltage is around 121, there will be a ballast resistor of some type, usually in the form of a big resistor, a resistance element in the line cord, or a ballast tube.
::
::Thomas
::
::Thomas
::
:::Thanks for the info. Any problem using a 50L6 instead of a 35L6?
:::
::::Hi Jeff,
::::The Zenith H615 (Chassis 6G05) is covered in Sams Photofact 140-14 (dated 7/51). It indicates this radio uses a 35L6 output tube, and either a 35Y4 or 35W4 rectifier tube. Filter caps are specified as 80mfd/40mfd @ 150v. I suspect the earlier cap replacement was done by a shop who happened to have those values in stock. Probably worked OK, as there is a wide tolerance range on electrolytic caps. No damage would be done to the radio with slightly smaller mfd caps, provided voltage rating was adequate. But filtering might not be as good, hence some hum could result. For replacement I would try to get a little closer to the original cap values.
::::
::::Poston
::::
::::
:::::Hi,
:::::I'm restoring a Zenith H615 I inherited and I'm wondering about the audio amp tube I found in it (a 50L6). After reviewing the schematics (for a G615, since I couldn't find H615 schematics), it appears the audio amp should be a 35L6. This radio hasn't been used much in the last 20 years, and I don't think it's been serviced in at least 35 years, which tells me that the 50L6 has been in there a long time. Is there a problem substituting a 50L6 for a 35L6? Would it need to draw the extra 15 volts to operate properly? Also, I'm replacing the electrolytic caps that appear to have been replaced at least once a long time ago. The G615 schematic calls for 40/80 multiple, however the old replacements are separate 30 and 50 mfd caps. I know it's a no-no to replace caps with smaller values, but what kind of damage could be caused by using the inferior valued caps?
:::::As always, any help is greatly appreciated!
:::::
:::::Jeff
Jeff Do you have a Schematic for the radio?
I need one for restoration.
Frank
Frank,
I used the schematic for a Zenith G615 (same chassis) that I got from the "Resources" on this website.
Good luck!
Jeff
How did things go with your H615?
I am working on a H615Z that was my grandfathers. The schematics I got from the Resources area show volume pot wiring that is different from the unit I have. Did you happen to trace the area of your volume pot and see a differance? In the unit I have the wiper of the pot routes through a 1 Meg resistor that then ties to switch power. The schematics show the wiper going to a cap (.01 or .007) to pin 1 (grid) of the 12AT6. Thought I would ask and see if you ran into this.
Thank you,
Rod
:Hi,
:I'm restoring a Zenith H615 I inherited and I'm wondering about the audio amp tube I found in it (a 50L6). After reviewing the schematics (for a G615, since I couldn't find H615 schematics), it appears the audio amp should be a 35L6. This radio hasn't been used much in the last 20 years, and I don't think it's been serviced in at least 35 years, which tells me that the 50L6 has been in there a long time. Is there a problem substituting a 50L6 for a 35L6? Would it need to draw the extra 15 volts to operate properly? Also, I'm replacing the electrolytic caps that appear to have been replaced at least once a long time ago. The G615 schematic calls for 40/80 multiple, however the old replacements are separate 30 and 50 mfd caps. I know it's a no-no to replace caps with smaller values, but what kind of damage could be caused by using the inferior valued caps?
:As always, any help is greatly appreciated!
:
:Jeff
:Hi Jeff,
:
:How did things go with your H615?
:
:I am working on a H615Z that was my grandfathers. The schematics I got from the Resources area show volume pot wiring that is different from the unit I have. Did you happen to trace the area of your volume pot and see a differance? In the unit I have the wiper of the pot routes through a 1 Meg resistor that then ties to switch power. The schematics show the wiper going to a cap (.01 or .007) to pin 1 (grid) of the 12AT6. Thought I would ask and see if you ran into this.
:
:Thank you,
: Rod
:
::Hi,
::I'm restoring a Zenith H615 I inherited and I'm wondering about the audio amp tube I found in it (a 50L6). After reviewing the schematics (for a G615, since I couldn't find H615 schematics), it appears the audio amp should be a 35L6. This radio hasn't been used much in the last 20 years, and I don't think it's been serviced in at least 35 years, which tells me that the 50L6 has been in there a long time. Is there a problem substituting a 50L6 for a 35L6? Would it need to draw the extra 15 volts to operate properly? Also, I'm replacing the electrolytic caps that appear to have been replaced at least once a long time ago. The G615 schematic calls for 40/80 multiple, however the old replacements are separate 30 and 50 mfd caps. I know it's a no-no to replace caps with smaller values, but what kind of damage could be caused by using the inferior valued caps?
::As always, any help is greatly appreciated!
::
::Jeff
I replaced a two tubes and the electrolytic capacitors, but that's about as far as I went. We moved recently and my H615 is still packed away. When I find it, I'll open it up and take a look at the pot to see how it's wired. I know mine's been repaired at least once but I didn't see anything that stood out as being different from the schematic. More later...
Good luck!
Jeff
:Hi Jeff,
:
:How did things go with your H615?
:
:I am working on a H615Z that was my grandfathers. The schematics I got from the Resources area show volume pot wiring that is different from the unit I have. Did you happen to trace the area of your volume pot and see a differance? In the unit I have the wiper of the pot routes through a 1 Meg resistor that then ties to switch power. The schematics show the wiper going to a cap (.01 or .007) to pin 1 (grid) of the 12AT6. Thought I would ask and see if you ran into this.
:
:Thank you,
: Rod
:
::Hi,
::I'm restoring a Zenith H615 I inherited and I'm wondering about the audio amp tube I found in it (a 50L6). After reviewing the schematics (for a G615, since I couldn't find H615 schematics), it appears the audio amp should be a 35L6. This radio hasn't been used much in the last 20 years, and I don't think it's been serviced in at least 35 years, which tells me that the 50L6 has been in there a long time. Is there a problem substituting a 50L6 for a 35L6? Would it need to draw the extra 15 volts to operate properly? Also, I'm replacing the electrolytic caps that appear to have been replaced at least once a long time ago. The G615 schematic calls for 40/80 multiple, however the old replacements are separate 30 and 50 mfd caps. I know it's a no-no to replace caps with smaller values, but what kind of damage could be caused by using the inferior valued caps?
::As always, any help is greatly appreciated!
::
::Jeff
:Jeff,
:Did you ever find a schematic for your H615? If not, email me. I have a Jpeg version.
:Jim bikindad@yahoo.com