Hello all- My Zenith 12-s-265 power transformer shorted out and caused a real stink!! What would you suggest as a replacement from Antique Electronic Supply? The radio was still playing when I noticed the stink and the oil coming out. I want to make sure I order the right one because this radio is a treasure to me because of the gentleman I acquired this set from passed away a few months after I got it. Thanks for any suggestions.
Ryan

Awesome! Zeniths are always cool no matter where they come from, but that's cool that you got it from someone who's special to you. Sad that he died, but cool that you have his set. Wish I could restore my car which belonged to my neighbors (husband and wife) who died recently.

Regarding the transformer, be absolutely sure that your electrolytics have no leakage before you replace it. Remove them from their associated circuits and test them with your multi-meter. After removing the electrolytics, check for any resistance between the cathode of the rectifier and the chassis. If there is any, then you may have other shorted condensers within the set. Before you do this you will have to disconnect all wires from the center and lower sections of R18 as shown in the diagram. Mark the wires carefully so that you can reconnect them to their appropriate sections.

If all condensers within the set check out fine, then you may continue to use them. If this is the case, then the transformer alone is at fault. If you find leaky condensers, then they may have been what overloaded the power transformer. If you find shorted or leaky condensers, pull the rectifier tube and turn the set on. See if you can run it for like a half hour or so without any tar leaking out of the transformer. If so, then your transformer may actually be good and may have simply been overloaded. If it tests out good in this case (with rectifier removed), replace all faulty electrolytics. Try out set normally again. If the transformer still overheats and leaks tar, then it is damaged. Antique Electronic Supply (www.tubesandmore.com) will then be a fine source for a new transformer. DO NOT REPLACE THE TRANSFORMER UNTIL YOU ARE SURE THAT NONE OF THE CONDENSERS WITHIN THE SET ARE FAULTY. If some are and you don't catch them, you'll ruin your new expensive transformer.

In order to determine the type of transformer you need, you will need to figure out the current drawn from the old one. Take the total wattage consumed from the radio. By using a tube manual, figure out what the total MA (milliamperes or thousandths of an ampere). that is drawn by all of the tube filaments. Each tube's MA. is given in a tube manual. Add these all together. This is the current that must be available from the filament winding. The rectifier's filament MA. determines the amount that the rectifier filament winding must be rated for.

Now, for the high voltage winding things get tricky, as the total MA. drawn by the radio's B circuit isn't often given in schematics. Take the total MA. for all of the 6.3 volt tubes (tubes beginning with the number six) and multiply this by 6.3. This will give you the total watts drawn by these filaments. Take the MA. for the rectifier filament and multiply this by 5.0 (5.0 volts). This will give you the wattage drawn by the rectifier filament. Add the two wattages together and subtract them from the total wattage drawn by the radio. The remaining wattage is that drawn by the B (high voltage) circuit. Take this number and divide it by the voltage used within the B circuit. This will give you the MA. drawn by your B circuit. Actually transformers are only about 85 to 90 percent efficient, so the actual current drawn by the B circuit may be a bit less. At any rate, now that you have the MA. drawn by the B circuit, the rectifier filament, and all the other tube filaments, you can purchase the appropriate transformer. I saw in your diagram that there is no mention of the B circuit voltage, so you may have to check around to find out what this is. It is most likely 350 volts. In that case you want a new transformer with a 350-0-350 center tapped B winding.

Thomas

I miswrote something in my previous post, so read this one instead when determining the size of your power transformer. I miswrote the part about determining the MA. drawn by the 6.3 volt tubes.

Awesome! Zeniths are always cool no matter where they come from, but that's cool that you got it from someone who's special to you. Sad that he died, but cool that you have his set. Wish I could restore my car which belonged to my neighbors (husband and wife) who died recently.
Regarding the transformer, be absolutely sure that your electrolytics have no leakage before you replace it. Remove them from their associated circuits and test them with your multi-meter. After removing the electrolytics, check for any resistance between the cathode of the rectifier and the chassis. If there is any, then you may have other shorted condensers within the set. Before you do this you will have to disconnect all wires from the center and lower sections of R18 as shown in the diagram. Mark the wires carefully so that you can reconnect them to their appropriate sections.

If all condensers within the set check out fine, then you may continue to use them. If this is the case, then the transformer alone is at fault. If you find leaky condensers, then they may have been what overloaded the power transformer. If you find shorted or leaky condensers, pull the rectifier tube and turn the set on. See if you can run it for like a half hour or so without any tar leaking out of the transformer. If so, then your transformer may actually be good and may have simply been overloaded. If it tests out good in this case (with rectifier removed), replace all faulty electrolytics. Try out set normally again. If the transformer still overheats and leaks tar, then it is damaged. Antique Electronic Supply (www.tubesandmore.com) will then be a fine source for a new transformer. DO NOT REPLACE THE TRANSFORMER UNTIL YOU ARE SURE THAT NONE OF THE CONDENSERS WITHIN THE SET ARE FAULTY. If some are and you don't catch them, you'll ruin your new expensive transformer.

In order to determine the type of transformer you need, you will need to figure out the current drawn from the old one. Take the total wattage consumed from the radio. By using a tube manual, figure out what the total MA (milliamperes or thousandths of an ampere). that is drawn by all of the tube filaments EXCEPT THE RECTIFIER. Each tube's MA. is given in a tube manual. Add these all together. This is the current that must be available from the 6.3 volt filament winding. The rectifier's filament MA. determines the amount that the rectifier filament winding (5.0 volt) must be rated for.

Now, for the high voltage winding things get tricky, as the total MA. drawn by the radio's B circuit isn't often given in schematics. Take the total MA. for all of the 6.3 volt tubes (tubes beginning with the number six) and multiply this by 6.3. This will give you the total watts drawn by these filaments. Take the MA. for the rectifier filament and multiply this by 5.0 (5.0 volts). This will give you the wattage drawn by the rectifier filament. Add the two wattages together and subtract them from the total wattage drawn by the radio. The remaining wattage is that drawn by the B (high voltage) circuit. Take this number and divide it by the voltage used within the B circuit. This will give you the MA. drawn by your B circuit. Actually transformers are only about 85 to 90 percent efficient, so the actual current drawn by the B circuit may be a bit less. At any rate, now that you have the MA. drawn by the B circuit, the rectifier filament, and all the other tube filaments, you can purchase the appropriate transformer. I saw in your diagram that there is no mention of the B circuit voltage, so you may have to check around to find out what this is. It is most likely 350 volts. In that case you want a new transformer with a 350-0-350 center tapped B winding.

Thomas

Thank you Thomas for all the greatly needed info. I'll see what I can come up with. Thanks again.
Ryan

:I miswrote something in my previous post, so read this one instead when determining the size of your power transformer. I miswrote the part about determining the MA. drawn by the 6.3 volt tubes.
:
:Awesome! Zeniths are always cool no matter where they come from, but that's cool that you got it from someone who's special to you. Sad that he died, but cool that you have his set. Wish I could restore my car which belonged to my neighbors (husband and wife) who died recently.
:Regarding the transformer, be absolutely sure that your electrolytics have no leakage before you replace it. Remove them from their associated circuits and test them with your multi-meter. After removing the electrolytics, check for any resistance between the cathode of the rectifier and the chassis. If there is any, then you may have other shorted condensers within the set. Before you do this you will have to disconnect all wires from the center and lower sections of R18 as shown in the diagram. Mark the wires carefully so that you can reconnect them to their appropriate sections.
:
:If all condensers within the set check out fine, then you may continue to use them. If this is the case, then the transformer alone is at fault. If you find leaky condensers, then they may have been what overloaded the power transformer. If you find shorted or leaky condensers, pull the rectifier tube and turn the set on. See if you can run it for like a half hour or so without any tar leaking out of the transformer. If so, then your transformer may actually be good and may have simply been overloaded. If it tests out good in this case (with rectifier removed), replace all faulty electrolytics. Try out set normally again. If the transformer still overheats and leaks tar, then it is damaged. Antique Electronic Supply (www.tubesandmore.com) will then be a fine source for a new transformer. DO NOT REPLACE THE TRANSFORMER UNTIL YOU ARE SURE THAT NONE OF THE CONDENSERS WITHIN THE SET ARE FAULTY. If some are and you don't catch them, you'll ruin your new expensive transformer.
:
:In order to determine the type of transformer you need, you will need to figure out the current drawn from the old one. Take the total wattage consumed from the radio. By using a tube manual, figure out what the total MA (milliamperes or thousandths of an ampere). that is drawn by all of the tube filaments EXCEPT THE RECTIFIER. Each tube's MA. is given in a tube manual. Add these all together. This is the current that must be available from the 6.3 volt filament winding. The rectifier's filament MA. determines the amount that the rectifier filament winding (5.0 volt) must be rated for.
:
:Now, for the high voltage winding things get tricky, as the total MA. drawn by the radio's B circuit isn't often given in schematics. Take the total MA. for all of the 6.3 volt tubes (tubes beginning with the number six) and multiply this by 6.3. This will give you the total watts drawn by these filaments. Take the MA. for the rectifier filament and multiply this by 5.0 (5.0 volts). This will give you the wattage drawn by the rectifier filament. Add the two wattages together and subtract them from the total wattage drawn by the radio. The remaining wattage is that drawn by the B (high voltage) circuit. Take this number and divide it by the voltage used within the B circuit. This will give you the MA. drawn by your B circuit. Actually transformers are only about 85 to 90 percent efficient, so the actual current drawn by the B circuit may be a bit less. At any rate, now that you have the MA. drawn by the B circuit, the rectifier filament, and all the other tube filaments, you can purchase the appropriate transformer. I saw in your diagram that there is no mention of the B circuit voltage, so you may have to check around to find out what this is. It is most likely 350 volts. In that case you want a new transformer with a 350-0-350 center tapped B winding.
:
:Thomas
:

It appears you may be able to help me with information on the type of Power Transformer I need to replace for my (Zenith 10-S-669, Ch. 10B1 (part number 95-833N).

Thanks for your help

:Awesome! Zeniths are always cool no matter where they come from, but that's cool that you got it from someone who's special to you. Sad that he died, but cool that you have his set. Wish I could restore my car which belonged to my neighbors (husband and wife) who died recently.
:
:Regarding the transformer, be absolutely sure that your electrolytics have no leakage before you replace it. Remove them from their associated circuits and test them with your multi-meter. After removing the electrolytics, check for any resistance between the cathode of the rectifier and the chassis. If there is any, then you may have other shorted condensers within the set. Before you do this you will have to disconnect all wires from the center and lower sections of R18 as shown in the diagram. Mark the wires carefully so that you can reconnect them to their appropriate sections.
:
:If all condensers within the set check out fine, then you may continue to use them. If this is the case, then the transformer alone is at fault. If you find leaky condensers, then they may have been what overloaded the power transformer. If you find shorted or leaky condensers, pull the rectifier tube and turn the set on. See if you can run it for like a half hour or so without any tar leaking out of the transformer. If so, then your transformer may actually be good and may have simply been overloaded. If it tests out good in this case (with rectifier removed), replace all faulty electrolytics. Try out set normally again. If the transformer still overheats and leaks tar, then it is damaged. Antique Electronic Supply (www.tubesandmore.com) will then be a fine source for a new transformer. DO NOT REPLACE THE TRANSFORMER UNTIL YOU ARE SURE THAT NONE OF THE CONDENSERS WITHIN THE SET ARE FAULTY. If some are and you don't catch them, you'll ruin your new expensive transformer.
:
:In order to determine the type of transformer you need, you will need to figure out the current drawn from the old one. Take the total wattage consumed from the radio. By using a tube manual, figure out what the total MA (milliamperes or thousandths of an ampere). that is drawn by all of the tube filaments. Each tube's MA. is given in a tube manual. Add these all together. This is the current that must be available from the filament winding. The rectifier's filament MA. determines the amount that the rectifier filament winding must be rated for.
:
:Now, for the high voltage winding things get tricky, as the total MA. drawn by the radio's B circuit isn't often given in schematics. Take the total MA. for all of the 6.3 volt tubes (tubes beginning with the number six) and multiply this by 6.3. This will give you the total watts drawn by these filaments. Take the MA. for the rectifier filament and multiply this by 5.0 (5.0 volts). This will give you the wattage drawn by the rectifier filament. Add the two wattages together and subtract them from the total wattage drawn by the radio. The remaining wattage is that drawn by the B (high voltage) circuit. Take this number and divide it by the voltage used within the B circuit. This will give you the MA. drawn by your B circuit. Actually transformers are only about 85 to 90 percent efficient, so the actual current drawn by the B circuit may be a bit less. At any rate, now that you have the MA. drawn by the B circuit, the rectifier filament, and all the other tube filaments, you can purchase the appropriate transformer. I saw in your diagram that there is no mention of the B circuit voltage, so you may have to check around to find out what this is. It is most likely 350 volts. In that case you want a new transformer with a 350-0-350 center tapped B winding.
:
:Thomas

Your high voltage winding should put out 325 volts (325-0-325). Your transformer should also have a 5.0 volt winding and a 6.3 volt winding. Information for finding correct amperages is listed below in my original article.

T.

:It appears you may be able to help me with information on the type of Power Transformer I need to replace for my (Zenith 10-S-669, Ch. 10B1 (part number 95-833N).
:
:Thanks for your help
:
::Awesome! Zeniths are always cool no matter where they come from, but that's cool that you got it from someone who's special to you. Sad that he died, but cool that you have his set. Wish I could restore my car which belonged to my neighbors (husband and wife) who died recently.
::
::Regarding the transformer, be absolutely sure that your electrolytics have no leakage before you replace it. Remove them from their associated circuits and test them with your multi-meter. After removing the electrolytics, check for any resistance between the cathode of the rectifier and the chassis. If there is any, then you may have other shorted condensers within the set. Before you do this you will have to disconnect all wires from the center and lower sections of R18 as shown in the diagram. Mark the wires carefully so that you can reconnect them to their appropriate sections.
::
::If all condensers within the set check out fine, then you may continue to use them. If this is the case, then the transformer alone is at fault. If you find leaky condensers, then they may have been what overloaded the power transformer. If you find shorted or leaky condensers, pull the rectifier tube and turn the set on. See if you can run it for like a half hour or so without any tar leaking out of the transformer. If so, then your transformer may actually be good and may have simply been overloaded. If it tests out good in this case (with rectifier removed), replace all faulty electrolytics. Try out set normally again. If the transformer still overheats and leaks tar, then it is damaged. Antique Electronic Supply (www.tubesandmore.com) will then be a fine source for a new transformer. DO NOT REPLACE THE TRANSFORMER UNTIL YOU ARE SURE THAT NONE OF THE CONDENSERS WITHIN THE SET ARE FAULTY. If some are and you don't catch them, you'll ruin your new expensive transformer.
::
::In order to determine the type of transformer you need, you will need to figure out the current drawn from the old one. Take the total wattage consumed from the radio. By using a tube manual, figure out what the total MA (milliamperes or thousandths of an ampere). that is drawn by all of the tube filaments. Each tube's MA. is given in a tube manual. Add these all together. This is the current that must be available from the 6.3 volt filament winding. The rectifier's filament MA. determines the amount that the rectifier filament winding (5.0 volt) must be rated for.
::
::Now, for the high voltage winding things get tricky, as the total MA. drawn by the radio's B circuit isn't often given in schematics. Take the total MA. for all of the 6.3 volt tubes (tubes beginning with the number six) and multiply this by 6.3. This will give you the total watts drawn by these filaments. Take the MA. for the rectifier filament and multiply this by 5.0 (5.0 volts). This will give you the wattage drawn by the rectifier filament. Add the two wattages together and subtract them from the total wattage drawn by the radio. The remaining wattage is that drawn by the B (high voltage) circuit. Take this number and divide it by the voltage used within the B circuit. This will give you the MA. drawn by your B circuit. Actually transformers are only about 85 to 90 percent efficient, so the actual current drawn by the B circuit may be a bit less. At any rate, now that you have the MA. drawn by the B circuit, the rectifier filament, and all the other tube filaments, you can purchase the appropriate transformer. I saw in your diagram that there is no mention of the B circuit voltage, so you may have to check around to find out what this is. It is most likely 350 volts. In that case you want a new transformer with a 350-0-350 center tapped B winding.
::
::Thomas