Hello All,
I'm working on an RCA tv from the late 50's but my problem could happen on any tv set. Somehow the plastic back cover of the yoke has disintegrated. It works fine but how do I hold it in place without a back cover? Also, the controls (tabbed metal rings) for the centering magnets are there but they don't seem to do anything (missing magnets?).
Does anyone have a suggestion for a substitute back cover?

I have another problem which requires the model number and I will post that separately.

Thanks,

Dave...

I had a friend who had a portable RCA Victor television from the early to mid 1950s. It's one of those really cool metal ones with the gold front, says RCA Victor on top of the front. Front also holds tinted safety glass. Sides are two tone with a golden chrome strip that runs between the colors. Speaker on left side, controls on the right. Uses such tubes as 6DE4, 5U4, 6DQ6, 1X2, and all the standard AF and RF tubes. This model was VHF only.

The plastic housing of the yoke fell apart on this one, as well as various other problems (HV tube, shorted condensers). If I remember correctly, the yoke and its plastic cover stayed together, but the part of the plastic that extended rearward over the neck of the tube (with the clamp and centering rings) had fallen apart. I think I wrapped a single layer (possibly more) of friction tape around the neck of the tube where the yoke was supposed to go. Friction tape is an old fashioned cloth electrical tape that is readily available at your hardware store...it is soft and sticks on both sides. With just enough friction tape on the neck of the tube up front, I was able to slide the yoke assembly up againts the bell, over the friction tape. The friction tape grabbed between the yoke center and the tube, and held the yoke in place. It gave just enough resistance to hold the yoke, but I could still turn the yoke to adjust the picture--keep this in mind if you do this. You don't want so much tension that you can't turn the yoke or that you have to force it, both for adjusting reasons and safety.

Then I cut a long piece of friction tape in half (for this procedure you can use something stronger like duct tape--stronger adhesive). I pieced the plastic pieces together orange peel style--how a cylinder would look if it was laid somewhat flat, so that they would be in proper order for wrapping around the neck of the tube. I placed the tape over the places at a convenient place where nothing was to go. Then I arranged the plastic pieces around a couple of my fingers and put the centering rings over this mess. I I placed the pieces held together with tape, along with the centering rings, onto the neck of the picture tube, and after some manipulation of the plastic pieces, managed to work them into the arrangement they had before they broke apart (a cylinder). Then I slid the assembly approximately where it normally goes, and wrapped the full length of tape around it to hold it together firmly. Then I placed the clamping ring around the end, moved the assembly into its proper place--where it normally goes when it is attached to the yoke, and gently tightened the clamp.

If the large cover portion of the plastic has fallen apart as well as the small part with the centering rings (originally both the cover and the neck extension were all one piece), as long as you can get the part that retains the centering rings to go back together, you don't really need the cover anymore. The yoke will stay on the neck of the tube quite well with the friction tape between it and the neck. You can try various glues and such, but these plastics can't take chemicals, and you may ruin things more. A fiberous material like dryer fabric softeners can be used in combination with some glue like liquid super glue to build up a repair. Careful with super glue, as you may glue together more than you want to. If you glue something to the neck of the picture tube and try to get it off, you may rupture the tube. You could try forming the plastic neck pieces back together over a piece of aluminum foil that has been wrapped around the neck of the tube. This would keep things from sticking to the tube. Just make the foil longer than necessary so that it can be taped together at one end so it holds its shape on the tube while you work. Use long, skinny strips of dryer fabric softener sheets in place of where you would put the tape in the previous method, and gradually soak these with super glue as you work them into place. Think about what you're doing and plan ahead. Analyze the situation thoroughly before making a move.

Don't know why your centering rings don't work. They only make subtle changes, really. If you rotate both at the same time, you won't see much. You have to rotate each individually to see something noticeable, though sometimes it is necessary to rotate both at the same time to get the desired effect, and so what I said above just states what you'll see when you move them in certain ways. In reality you must move each or both any way you see fit to get the desired result. Usually, when I have found centering rings on a television, the rings themselves (as thin as they are) are the magnets. I'm sure there's a television somewhere out there that has rings with actual magnets attached, but usually the rings, whenever I see them, are the magnets. Each ring has a magnetic polarity--one side is North, and the other is South. The rings are very weak magnets. It is slightly possible that they have lost their magnatism, but not likely. Get the yoke together as it should be, and experiment around with everything before you conclude that they have lost their magnatism.

Thomas

:Hello All,
: I'm working on an RCA tv from the late 50's but my problem could happen on any tv set. Somehow the plastic back cover of the yoke has disintegrated. It works fine but how do I hold it in place without a back cover? Also, the controls (tabbed metal rings) for the centering magnets are there but they don't seem to do anything (missing magnets?).
: Does anyone have a suggestion for a substitute back cover?
:
: I have another problem which requires the model number and I will post that separately.
:
:Thanks,
:
:Dave...

Thomas,
Thanks I will try the friction tape idea.
I now have some sync problems (weak tubes) and the verical height shaft no longer has a slot. Someone broke off that part of the plastic. But I don't think I'll have trouble adjusting it.
It works fine. I have replaced all paper + filter capacitors. The yoke was the biggest problem. I knew it would work without the cover. I just wanted to secure it.

Thanks again,

Dave...
:I had a friend who had a portable RCA Victor television from the early to mid 1950s. It's one of those really cool metal ones with the gold front, says RCA Victor on top of the front. Front also holds tinted safety glass. Sides are two tone with a golden chrome strip that runs between the colors. Speaker on left side, controls on the right. Uses such tubes as 6DE4, 5U4, 6DQ6, 1X2, and all the standard AF and RF tubes. This model was VHF only.
:
:The plastic housing of the yoke fell apart on this one, as well as various other problems (HV tube, shorted condensers). If I remember correctly, the yoke and its plastic cover stayed together, but the part of the plastic that extended rearward over the neck of the tube (with the clamp and centering rings) had fallen apart. I think I wrapped a single layer (possibly more) of friction tape around the neck of the tube where the yoke was supposed to go. Friction tape is an old fashioned cloth electrical tape that is readily available at your hardware store...it is soft and sticks on both sides. With just enough friction tape on the neck of the tube up front, I was able to slide the yoke assembly up againts the bell, over the friction tape. The friction tape grabbed between the yoke center and the tube, and held the yoke in place. It gave just enough resistance to hold the yoke, but I could still turn the yoke to adjust the picture--keep this in mind if you do this. You don't want so much tension that you can't turn the yoke or that you have to force it, both for adjusting reasons and safety.
:
:Then I cut a long piece of friction tape in half (for this procedure you can use something stronger like duct tape--stronger adhesive). I pieced the plastic pieces together orange peel style--how a cylinder would look if it was laid somewhat flat, so that they would be in proper order for wrapping around the neck of the tube. I placed the tape over the places at a convenient place where nothing was to go. Then I arranged the plastic pieces around a couple of my fingers and put the centering rings over this mess. I I placed the pieces held together with tape, along with the centering rings, onto the neck of the picture tube, and after some manipulation of the plastic pieces, managed to work them into the arrangement they had before they broke apart (a cylinder). Then I slid the assembly approximately where it normally goes, and wrapped the full length of tape around it to hold it together firmly. Then I placed the clamping ring around the end, moved the assembly into its proper place--where it normally goes when it is attached to the yoke, and gently tightened the clamp.
:
:If the large cover portion of the plastic has fallen apart as well as the small part with the centering rings (originally both the cover and the neck extension were all one piece), as long as you can get the part that retains the centering rings to go back together, you don't really need the cover anymore. The yoke will stay on the neck of the tube quite well with the friction tape between it and the neck. You can try various glues and such, but these plastics can't take chemicals, and you may ruin things more. A fiberous material like dryer fabric softeners can be used in combination with some glue like liquid super glue to build up a repair. Careful with super glue, as you may glue together more than you want to. If you glue something to the neck of the picture tube and try to get it off, you may rupture the tube. You could try forming the plastic neck pieces back together over a piece of aluminum foil that has been wrapped around the neck of the tube. This would keep things from sticking to the tube. Just make the foil longer than necessary so that it can be taped together at one end so it holds its shape on the tube while you work. Use long, skinny strips of dryer fabric softener sheets in place of where you would put the tape in the previous method, and gradually soak these with super glue as you work them into place. Think about what you're doing and plan ahead. Analyze the situation thoroughly before making a move.
:
:Don't know why your centering rings don't work. They only make subtle changes, really. If you rotate both at the same time, you won't see much. You have to rotate each individually to see something noticeable, though sometimes it is necessary to rotate both at the same time to get the desired effect, and so what I said above just states what you'll see when you move them in certain ways. In reality you must move each or both any way you see fit to get the desired result. Usually, when I have found centering rings on a television, the rings themselves (as thin as they are) are the magnets. I'm sure there's a television somewhere out there that has rings with actual magnets attached, but usually the rings, whenever I see them, are the magnets. Each ring has a magnetic polarity--one side is North, and the other is South. The rings are very weak magnets. It is slightly possible that they have lost their magnatism, but not likely. Get the yoke together as it should be, and experiment around with everything before you conclude that they have lost their magnatism.
:
:Thomas
:
::Hello All,
:: I'm working on an RCA tv from the late 50's but my problem could happen on any tv set. Somehow the plastic back cover of the yoke has disintegrated. It works fine but how do I hold it in place without a back cover? Also, the controls (tabbed metal rings) for the centering magnets are there but they don't seem to do anything (missing magnets?).
:: Does anyone have a suggestion for a substitute back cover?
::
:: I have another problem which requires the model number and I will post that separately.
::
::Thanks,
::
::Dave...

Can we assume that the bulk of the back of the yoke cover is intact, just a distenegration of the portion that was clamped to the hot kine neck and supportys the centering ring pair.....and, yes the two pieces themselves are magnetized, but will have minumal effect until nestled together again and positioned properly again at the rear of the yokes rear dust cover.If there is still periperal plastic left I would look into fabricating a replacement plastic disc with centwer kine clearance hole and hand fabbing a short cardboard tube the inside ID of the centering ring holes and lightly epoxying it to the replacement plastic disc. Two neophrene "o" rings can hold tension on the centering mag tabs.
73's de Edd
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
:Hello All,
: I'm working on an RCA tv from the late 50's but my problem could happen on any tv set. Somehow the plastic back cover of the yoke has disintegrated. It works fine but how do I hold it in place without a back cover? Also, the controls (tabbed metal rings) for the centering magnets are there but they don't seem to do anything (missing magnets?).
: Does anyone have a suggestion for a substitute back cover?
:
: I have another problem which requires the model number and I will post that separately.
:
:Thanks,
:
:Dave...

Edd,
The entire cover encluding the part that gets clamped on crumbled. It looked to me like insects at first. But then I realized that it was the plastic. Now the set is working fine and I will use the friction tape idea. I hope the friction tape can handle the heat of the picture tube ok. The rings metal supports are still holding them on the tube. I don't want to take off the clamp or the ion trap. So if I do add any kind of new back to the yoke, it will be in two halves.

Dave...
:Can we assume that the bulk of the back of the yoke cover is intact, just a distenegration of the portion that was clamped to the hot kine neck and supportys the centering ring pair.....and, yes the two pieces themselves are magnetized, but will have minumal effect until nestled together again and positioned properly again at the rear of the yokes rear dust cover.If there is still periperal plastic left I would look into fabricating a replacement plastic disc with centwer kine clearance hole and hand fabbing a short cardboard tube the inside ID of the centering ring holes and lightly epoxying it to the replacement plastic disc. Two neophrene "o" rings can hold tension on the centering mag tabs.
:73's de Edd
:-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
::Hello All,
:: I'm working on an RCA tv from the late 50's but my problem could happen on any tv set. Somehow the plastic back cover of the yoke has disintegrated. It works fine but how do I hold it in place without a back cover? Also, the controls (tabbed metal rings) for the centering magnets are there but they don't seem to do anything (missing magnets?).
:: Does anyone have a suggestion for a substitute back cover?
::
:: I have another problem which requires the model number and I will post that separately.
::
::Thanks,
::
::Dave...

The friction tape will get hard with age. Unless the yoke is moved after the tape has hardened, you will have no problems. If it is moved after the tape has hardened, you will have to replace the tape. Be sure to not use too much tape, or you won't be able to get the yoke off the tube after the tape hardens.

Don't be afraid to remove the ion trap. Just draw an arrow on it, or color the half that faces the front of the set with a black marker. Once you remove it, when you replace it, all that is necessary is to rotate it around slowly and also move it slightly forward or rearward from its general resting spot when last removed. Do this until you obtain a picture. Then very carefully adjust for brightest picture. If the magnet is on backwards, you will not find a place where you get a picture. The ion trap can also have a slight affect on focus and picture position. Usually it has no affect, though.

I'm surprised that your set has an ion trap. The set I worked on of similar vintage had an aluminized picture tube, which doesn't require an ion trap. Well, there was some transition during that time, so anything is possible.

Thomas

:Edd,
:The entire cover encluding the part that gets clamped on crumbled. It looked to me like insects at first. But then I realized that it was the plastic. Now the set is working fine and I will use the friction tape idea. I hope the friction tape can handle the heat of the picture tube ok. The rings metal supports are still holding them on the tube. I don't want to take off the clamp or the ion trap. So if I do add any kind of new back to the yoke, it will be in two halves.
:
:Dave...
::Can we assume that the bulk of the back of the yoke cover is intact, just a distenegration of the portion that was clamped to the hot kine neck and supportys the centering ring pair.....and, yes the two pieces themselves are magnetized, but will have minumal effect until nestled together again and positioned properly again at the rear of the yokes rear dust cover.If there is still periperal plastic left I would look into fabricating a replacement plastic disc with centwer kine clearance hole and hand fabbing a short cardboard tube the inside ID of the centering ring holes and lightly epoxying it to the replacement plastic disc. Two neophrene "o" rings can hold tension on the centering mag tabs.
::73's de Edd
::-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
:::Hello All,
::: I'm working on an RCA tv from the late 50's but my problem could happen on any tv set. Somehow the plastic back cover of the yoke has disintegrated. It works fine but how do I hold it in place without a back cover? Also, the controls (tabbed metal rings) for the centering magnets are there but they don't seem to do anything (missing magnets?).
::: Does anyone have a suggestion for a substitute back cover?
:::
::: I have another problem which requires the model number and I will post that separately.
:::
:::Thanks,
:::
:::Dave...

:Hello All,
: I'm working on an RCA tv from the late 50's but my problem could happen on any tv set. Somehow the plastic back cover of the yoke has disintegrated. It works fine but how do I hold it in place without a back cover? Also, the controls (tabbed metal rings) for the centering magnets are there but they don't seem to do anything (missing magnets?).
: Does anyone have a suggestion for a substitute back cover?
Dave: I have serviced literally thousands of those 50's tv sets and understand your problem. It was not the heat of the CRT but was the ozone attacking the yoke housing. Horizontal sweep currents in the yoke contained some RF and produced corona which changed the oxygen into ozone. This ozone then broke down the plastic - some models were worse then others. DuMont and Motorola were the worst at this. Their yokes would often become powder. All of the 50's RCA sets did use an ion trap, aluminizing had nothing to do with it. Setting the ion trap is not a big deal but is important.
I would try removing the 2 interlocking centering rings completely and see if the raster centers up which I think it will. Your chassis number starts with a KCS - - - Tom.
:
: I have another problem which requires the model number and I will post that separately.
:
:Thanks,
:
:Dave...

Well folks, not all the 1950s sets used the ion trap magnet. Done plenty of research, have plenty of books FROM THE 1950s, and even have a friend with a 1950s RCA Victor television that HAS NO ION TRAP MAGNET!

ION TRAP MAGNETS ARE NOT USUALLY PUT ON ALUMINIZED TUBES BECAUSE THE ALUMINUM FILM NATURALLY CATCHES THE IONS AND DOESN'T ALLOW THEM TO TOUCH THE PHOSPHOROUS SCREEN. ANYONE WANTING PROOF OF A 1950S MODEL WITHOUT THE ION TRAP MAGNET, OR A FULL LENGTH ARTICLE STATING WHEN AN ION TRAP MAGNET IS NECESSARY AND WHEN IT IS NOT, FROM THE INDUSTRIAL TRAINING INSTITUTE OF CHICAGO (TECHNICAL TRAINING CORRESPONDENCE COURCE, Copyright 1950), AND ANOTHER FROM A FIX IT YOURSELF ARTICLE, I WILL SCAN BOTH AND PUT THEM UP FOR ALL TO READ.

THERE ALSO WERE PICTURE TUBES OF THE 1950S WITH ANGLED ELECTRON GUNS, AND THEY DID NOT REQUIRE ION TRAP MAGNETS, EITHER. THE ELECTRON STREAM WAS DIRECTED AT THE AQUADAG, AND THEN THE DEFLECTION CIRCUITS WERE REQUIRED TO STRAIGHTEN IT OUT AGAIN RIGHT AWAY. THE ELECTRONS STRAIGHTENED OUT AND WENT ON THEIR WAY TO THE SCREEN, AND THE HEAVY IONS CONTINUED INTO THE AQUADAG WHERE THEY WERE SAFELY CARRIED AWAY.

Tom,
Why all the shouting (capital letters)? The set I have here has an ion trap and it's from 1957.

Dave...
:Well folks, not all the 1950s sets used the ion trap magnet. Done plenty of research, have plenty of books FROM THE 1950s, and even have a friend with a 1950s RCA Victor television that HAS NO ION TRAP MAGNET!
:
:ION TRAP MAGNETS ARE NOT USUALLY PUT ON ALUMINIZED TUBES BECAUSE THE ALUMINUM FILM NATURALLY CATCHES THE IONS AND DOESN'T ALLOW THEM TO TOUCH THE PHOSPHOROUS SCREEN. ANYONE WANTING PROOF OF A 1950S MODEL WITHOUT THE ION TRAP MAGNET, OR A FULL LENGTH ARTICLE STATING WHEN AN ION TRAP MAGNET IS NECESSARY AND WHEN IT IS NOT, FROM THE INDUSTRIAL TRAINING INSTITUTE OF CHICAGO (TECHNICAL TRAINING CORRESPONDENCE COURCE, Copyright 1950), AND ANOTHER FROM A FIX IT YOURSELF ARTICLE, I WILL SCAN BOTH AND PUT THEM UP FOR ALL TO READ.
:
:THERE ALSO WERE PICTURE TUBES OF THE 1950S WITH ANGLED ELECTRON GUNS, AND THEY DID NOT REQUIRE ION TRAP MAGNETS, EITHER. THE ELECTRON STREAM WAS DIRECTED AT THE AQUADAG, AND THEN THE DEFLECTION CIRCUITS WERE REQUIRED TO STRAIGHTEN IT OUT AGAIN RIGHT AWAY. THE ELECTRONS STRAIGHTENED OUT AND WENT ON THEIR WAY TO THE SCREEN, AND THE HEAVY IONS CONTINUED INTO THE AQUADAG WHERE THEY WERE SAFELY CARRIED AWAY.
:
:

Twas emphasizing key points to someone, but not shouting. It is possible that your television was manufactured with or without an ion trap magnet. During this time, sets were available with and without them.

T.

Tom,
The yoke had slid too far back and I had a burned resistor, which I replaced, and everything, except the sound, is fine now. The sound is a bit off and I have to find the coil to adjust it back to where it should be so that the picture is tuned in at the same time (in the same place in the fine tuning) as the sound. The sound is fine. The picture is fine but I cannot tune them in at the same time. So I need to make an adjustment.

14-S-7070U is the model number I believe. I don't see the chassis number anywhere. But I am familiar with RCA chassis numbers.
My guess is that it's near the sound detector tube somewhere.

Dave...
::Hello All,
:: I'm working on an RCA tv from the late 50's but my problem could happen on any tv set. Somehow the plastic back cover of the yoke has disintegrated. It works fine but how do I hold it in place without a back cover? Also, the controls (tabbed metal rings) for the centering magnets are there but they don't seem to do anything (missing magnets?).
:: Does anyone have a suggestion for a substitute back cover?
:Dave: I have serviced literally thousands of those 50's tv sets and understand your problem. It was not the heat of the CRT but was the ozone attacking the yoke housing. Horizontal sweep currents in the yoke contained some RF and produced corona which changed the oxygen into ozone. This ozone then broke down the plastic - some models were worse then others. DuMont and Motorola were the worst at this. Their yokes would often become powder. All of the 50's RCA sets did use an ion trap, aluminizing had nothing to do with it. Setting the ion trap is not a big deal but is important.
:I would try removing the 2 interlocking centering rings completely and see if the raster centers up which I think it will. Your chassis number starts with a KCS - - - Tom.
::
:: I have another problem which requires the model number and I will post that separately.
::
::Thanks,
::
::Dave...

Dave: It really helps me to have the RCA chassis number. I was an RCA dealer for 25 years back then and our factory service data is indexed to those numbers. The reason for this lies in the fact that the model numbers were cabinet and trim influenced while the chassis numbers were strictly electronic. To address your most recent problem with picture and sound staggering: The video is 4.5 mc away from the FM sound carrier. In your set, that difference has been compromised by non alignment. Does it act the same on all channels?? If it does, the alignment problem lies in the video I.F. strip and is most likely in the 3rd I.F. stage right at the 4.5 MHz sound take-off coil. The ideal and only good way to align this is to use a sweep generator with markers so that you can "touch up" the alignment and get the relationships correct. Since you need to align this set anyway, try this. Tune in the best video possible and then CAREFULLY adjust the sound take-off coil being careful to note its original position. Good luck and let me know if I can be of help. Tom.
: The yoke had slid too far back and I had a burned resistor, which I replaced, and everything, except the sound, is fine now. The sound is a bit off and I have to find the coil to adjust it back to where it should be so that the picture is tuned in at the same time (in the same place in the fine tuning) as the sound. The sound is fine. The picture is fine but I cannot tune them in at the same time. So I need to make an adjustment.
:
:14-S-7070U is the model number I believe. I don't see the chassis number anywhere. But I am familiar with RCA chassis numbers.
: My guess is that it's near the sound detector tube somewhere.
:
:Dave...
:::Hello All,
::: I'm working on an RCA tv from the late 50's but my problem could happen on any tv set. Somehow the plastic back cover of the yoke has disintegrated. It works fine but how do I hold it in place without a back cover? Also, the controls (tabbed metal rings) for the centering magnets are there but they don't seem to do anything (missing magnets?).
::: Does anyone have a suggestion for a substitute back cover?
::Dave: I have serviced literally thousands of those 50's tv sets and understand your problem. It was not the heat of the CRT but was the ozone attacking the yoke housing. Horizontal sweep currents in the yoke contained some RF and produced corona which changed the oxygen into ozone. This ozone then broke down the plastic - some models were worse then others. DuMont and Motorola were the worst at this. Their yokes would often become powder. All of the 50's RCA sets did use an ion trap, aluminizing had nothing to do with it. Setting the ion trap is not a big deal but is important.
::I would try removing the 2 interlocking centering rings completely and see if the raster centers up which I think it will. Your chassis number starts with a KCS - - - Tom.
:::
::: I have another problem which requires the model number and I will post that separately.
:::
:::Thanks,
:::
:::Dave...

Tom,
I will try to look for a chassis number. Also, without a printed picture, I do not know which coil it is and where it's located. Yes I am "hearing" the picture in the sound. Yes, it is the same on all channels.
I cannot find any chassis number anywhere in that set. All I can find is KRK part numbers on the tuners and what looks like a serial number etched into the chassis. It must have been on a label that's now missing. I looked at the tube chart label, its not there. The cover on the HV box has none either. All there is is a label on the bottom of the cabinet that says "Model number 14-S-7070U". There isn't anything on the back either. I had to have the chassis out so I could replace the paper and filter capacitors, and there aren't any numbers I could see there either. Sorry.

Dave...
:Dave: It really helps me to have the RCA chassis number. I was an RCA dealer for 25 years back then and our factory service data is indexed to those numbers. The reason for this lies in the fact that the model numbers were cabinet and trim influenced while the chassis numbers were strictly electronic. To address your most recent problem with picture and sound staggering: The video is 4.5 mc away from the FM sound carrier. In your set, that difference has been compromised by non alignment. Does it act the same on all channels?? If it does, the alignment problem lies in the video I.F. strip and is most likely in the 3rd I.F. stage right at the 4.5 MHz sound take-off coil. The ideal and only good way to align this is to use a sweep generator with markers so that you can "touch up" the alignment and get the relationships correct. Since you need to align this set anyway, try this. Tune in the best video possible and then CAREFULLY adjust the sound take-off coil being careful to note its original position. Good luck and let me know if I can be of help. Tom.
:: The yoke had slid too far back and I had a burned resistor, which I replaced, and everything, except the sound, is fine now. The sound is a bit off and I have to find the coil to adjust it back to where it should be so that the picture is tuned in at the same time (in the same place in the fine tuning) as the sound. The sound is fine. The picture is fine but I cannot tune them in at the same time. So I need to make an adjustment.
::
::14-S-7070U is the model number I believe. I don't see the chassis number anywhere. But I am familiar with RCA chassis numbers.
:: My guess is that it's near the sound detector tube somewhere.
::
::Dave...
::::Hello All,
:::: I'm working on an RCA tv from the late 50's but my problem could happen on any tv set. Somehow the plastic back cover of the yoke has disintegrated. It works fine but how do I hold it in place without a back cover? Also, the controls (tabbed metal rings) for the centering magnets are there but they don't seem to do anything (missing magnets?).
:::: Does anyone have a suggestion for a substitute back cover?
:::Dave: I have serviced literally thousands of those 50's tv sets and understand your problem. It was not the heat of the CRT but was the ozone attacking the yoke housing. Horizontal sweep currents in the yoke contained some RF and produced corona which changed the oxygen into ozone. This ozone then broke down the plastic - some models were worse then others. DuMont and Motorola were the worst at this. Their yokes would often become powder. All of the 50's RCA sets did use an ion trap, aluminizing had nothing to do with it. Setting the ion trap is not a big deal but is important.
:::I would try removing the 2 interlocking centering rings completely and see if the raster centers up which I think it will. Your chassis number starts with a KCS - - - Tom.
::::
:::: I have another problem which requires the model number and I will post that separately.
::::
::::Thanks,
::::
::::Dave...