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  #31  
Old 05-19-2018, 07:35 PM
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In a multiple-section electrolytic can capacitor, all the negative terminals of all the individual sections are connected to the outer can, and the positive terminals are the separate solder lugs that protrude through the bottom cardboard (not any twist lugs that connect the can to the chassis). When replacing one of these sections, you must remove any wire(s) that go(es) to the positive terminal of that section and connect them to the positive terminal of the replacement capacitor. The negative terminal of the replacement then has to be connected to the same place as the multi-section can (usually chassis ground).

Since you didn't realize the polarity is marked +, you had a 50/50 chance of getting it backward, and you should consider the replacement ruined and discard it.
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Last edited by old_tv_nut; 05-19-2018 at 07:39 PM.
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  #32  
Old 05-20-2018, 02:37 AM
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On modern axial lead caps the negative lead will be connected to the outer metallic case, the positive lead will come out of some insulating material. Never assume the polarity markings on the outside wrapper are correct. I've seen several where the heat shrink cover was installed with the polarity reversed.

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  #33  
Old 05-20-2018, 03:12 PM
Wind157 Wind157 is offline
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That's good info, thanks.

The cap was from mouse and while I saw the plus sign the SAMS nor the can indicated where positive polarity went.

That said the cap still doesn't matter as the problem I was trying to fix with it no longer occurs.

I am assuming the yellow wire coming of the can and leading to the vertical control had a bad solder where it connects to one of the tubes.
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  #34  
Old 05-20-2018, 09:53 PM
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I truley have no idea why the picture comes in good now. Smoking a resistor and it works now with keeping the old cap in place? Also the yellow wire running from that can to a tube then to the vertical control doesn't seem to do anything. I have a alligator clipped wire connecting the two yellow wires, after I cut it from the soldered point on the tube, and when I disconnected the clip the picture stayed on.
Not complaining but I don't see how anything I've done fixed the problem with the picture.
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  #35  
Old 05-20-2018, 11:11 PM
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Has the vertical oscillator or vertical output tube yet been subbed with another one to eliminate that as a possible problem yet? You will still need to replace that smoked resistor and I would still replace the cap again. That resistor could be a plate bias or something vital for correct operation. This set will look really nice when you get the problem figured out. The jug is in excellent condition.
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  #36  
Old 05-21-2018, 11:48 AM
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The tubes seem fine, I have some NOS I switched out and made no difference. I know I need to replace the resistor now. What I don't understand is why the part of the screen that was not displaying an image before now does so when with the same old capacitor. You can see in the attached that the picture on the left is not reaching the bottom of the screen and the picture on the right is filling the screen.
Those are pre/post smoking the resistor but the old cap is still in place. The only other change is the wire going from the Cap's can to a tube then to the vertical control but unhooking the alligator clipping it back to the tube makes no difference in picture quality.
So I guess I will replace the resistor but I am leaving the old capacitor in place as I am getting a full and good picture with it. Why I didn't before I do not know but I am now at the: if it's not broke, don't fix it, stage with the capacitor
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  #37  
Old 05-21-2018, 12:36 PM
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Possible the smoked resistor shifted tube bias to counteract the problem. Even if a cap in any given stage is not causing an immediate problem you still need to change the lytics and all tubular caps .001uF and up...They will eventually short and kill something MUCH harder to source.
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  #38  
Old 05-21-2018, 12:55 PM
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I assume you think replacing the resistor will cause the vertical linearity problem to start occuring again then?
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  #39  
Old 05-21-2018, 01:05 PM
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Quote:
Originally Posted by Wind157 View Post
I assume you think replacing the resistor will cause the vertical linearity problem to start occur again then?
It is possible but not guaranteed...Worry about having the parts meet spec before worrying about having it work perfectly...Otherwise, parts that have not been made in 50 years may be the next to smoke (due to bad caps, etc.)...

When I was a broke college student I used to try and get by replacing the minimum number of parts...So I can tell you from experience in most cases leave well enough alone (on old defective/risky parts ) = causing a worse failure in the near future.
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  #40  
Old 05-21-2018, 07:29 PM
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Yeah my luck is typically that I break something when fixing it though.
I suppose I should take the meter and check the various caps. It's just replacing the caps in the can, I feel like I'm flying blind without know exactly where to connect the replacement cap. Wish I could just find a replacement can instead of three separate caps.
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  #41  
Old 05-21-2018, 08:21 PM
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Quote:
Originally Posted by Wind157 View Post
Yeah my luck is typically that I break something when fixing it though.
I suppose I should take the meter and check the various caps. It's just replacing the caps in the can, I feel like I'm flying blind without know exactly where to connect the replacement cap. Wish I could just find a replacement can instead of three separate caps.
DMMs and solid state meters only check for capacitance...Most paper caps and ~half of lytics fail by leaking DC current across their terminals. A 400V rated cap may only start to leak with 300V or more across it. SolidState meters only apply around 5V to 12V not even close to being able to smoke out the issue. I use a tube type Heathkit C3 cap tester that can check for leakage by applying up to 450V...The only true validation of a vintage cap is applying its full rated voltage to it, and even then most paper caps and vintage lytics are so unreliable that it could(and often does) test good now, then in a week short dead and burn up some unobtainium coil.

No one makes real cans like those (the last vanished in the early 80's), there is one place that makes repops by stuffing individual modern caps into a can (not how the originals were made)...They charge way more than replacing with individual parts and are not worth it. Find your self an original cap that has been removed from a set and look it over carefully...They are not that complicated. Depending on the size of the can there will be 3-4 outer (negative) lugs connected to the outer metal can and 1-4 inner (positive) lugs connected to the center insulating wafer. The can metal is always negative in tube gear as are the outer lugs. The positive lugs in cans that have more than one section are differentiated from each other with the following symbols "^", "D", "[]", "-"(or" ") those symbols will either be scratched on the insulator around the terminals, or will be cut out of the insulator as an enlargement of the hole the positive terminal protrudes from. The metal on the can will have printed on it a label showing in a table the capacitance, voltage and terminal ID symbol of the positive sections. If you or a 5-year-old were in the same room with me and one of those caps I could teach both of you to read and change can caps (assuming prior knowledge of soldering) in around 3 minutes.

The thing about tube sets is they are eventually going to die at random from original caps as long as you leave them in...Better to change them all now one at a time while it works than wait for it to die...If you kill it while working now you can find your mistake easy if you go one or two caps at a time and check after doing those 1-2. But if you wait for the original caps to kill the set and then recap a dead set you have NO way to know you made a mistake...You'll end up changing every single cap and at the end not know if there are other issues or if you screwed up.

I get that a TV can be overwhelming, I try to advise people that want to eventually restore a TV to get a couple of 5 tube AM radios to practice recap work on those first...Much simpler than a TV, forgiving, cheap, and somewhat disposable for tube gear.
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  #42  
Old 05-21-2018, 09:31 PM
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I had figured out how to read the can and it's caps and order a replacement but thanks for the details, they're helpful. I did get the new cap connected and it looks better and the vert control works fully again.
There are 80 some caps, you said you'd recommend replacing all of them above a certain value?
It amazes me any of them still work on a 1957 set. Are there other known to fail components I should look at replacing?
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  #43  
Old 05-24-2018, 08:41 PM
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Would it be unusual for a SAMS to be wrong on it's picture showing where and which caps are which?
I asked because the SAMS page showing that has a few paper caps which are have been replaced. I assume someone previously did so. However there is at least one cause I have found where there is a paper can in place but it's not shown in the the image.
Is it logical to assume that there could be variant designs of the same model TV as everything else I can see matches the images, diagrams, part numbers?
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  #44  
Old 05-24-2018, 09:24 PM
WISCOJIM WISCOJIM is offline
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Soldering looks original as if nothing has been replaced. Which one in the picture do you think was replaced?

.
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  #45  
Old 05-24-2018, 09:44 PM
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Quote:
Originally Posted by WISCOJIM View Post
Soldering looks original as if nothing has been replaced. Which one in the picture do you think was replaced?

.
This one. I doubt it's been replaced as it's a paper cap but I don't see it pictured either.
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