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.

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?

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?

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.

Looks original, probably just a production change. Doesn't mean Sams is wrong, often manufacturers make a lot of changes along the line.

This also makes me suspect it's had work done too. The cap in the picture shows a paper cap but the one in place clearly isn't. It isn't new either so either it's been replaced some time ago or a different one was used in the first place.

Not sure where things are at but I think you are referring to C56.
Sams shows a white paper cap. The TV has a bumblebee.
Probably the factory changed suppliers.

As far as the original vert problem goes replace the burned resistor.
See if it still works. Its possable whatever went wrong it shocked a cap into
working again.

73 Zeno:smoke:
LFOD !

I did connect the cap to the wrong spot and now that it's in the right place and old cap removed it works great. Still will need to replace the resistor and other caps but working for the moment.
Thanks for everyone's help.

BTW when we say paper caps we are referring to the dielectric inside the cap and not it's outer casing. The white tubular ceramic caps in some of the pictures and the aforementioned bumblebee caps are paper dielectric caps, and should be changed.

Last question and it probably sounds dumb but it's my luck is pick wrong. When ordering a new cap I want to look for AC caps correct?

delete duplicate.

AC caps are almost never seen in TVs. Lytics and paper caps both new and original are and were rated for DC voltage.

Many new film/paper types are given both AC and DC voltage ratings... ignore the AC rating and choose new ones based on their DC voltage rating.

In most applications a cap would have something like 400VDC across it and maybe 5VAC of signal.... if it can handle the 400 DC then it can handle the 5 ac easily.

Glad I asked then.

How far below capacitance can I go? I need to replace one that is 150 but closest is 120 and that's with being a good deal higher in voltage

Lytics typically were +100%/-50% tolerance on the capacitance so 75uF would be the lowest you can go on a 150uF. Papers typically have a 10% tolerance. Most sets don't mind some variance in the capacitance of lytics, but papers can be more critical especially in any stage of a TV other than audio or power. In some cases (usually paper caps) if I don't feel I can get a precise enough value for the circuit I'll put two capacitors in parallel to get the value I need (capacitances in parallel add).

The closer the better but 120 should be plenty close to 150...If you get excessive hum on the line it filters after the recap you can always tack a 33 or more on in parallel with the 120 after the fact.

Thanks. I ended up finding one at 140 but voltage was 400 instead of 300. Fitting it will be fun.

...

Replacing the caps in a can, the negative of the new cap connects to ground?

The negative of the new cap(s) connects to whatever the metal housing of the original can connected to...

Many cans were soldered directly to chassis ground, but others rather than connecting the can to ground, connected it to a floating negative rail.
The original can will have 3-4 outer twist tabs coming from it's bottom...If the twist tabs contact and are soldered to the chassis metal then the can is grounded to chassis....But if the twist tabs are twisted onto a phenolic insulating wafer (the wafer is riveted to the chassis in 2 places) then the can connects to a floating negative rail (and your replacement(s) should then connect to the floating negative rail instead of the chassis). Another giveaway that a can is on a floating negative is when the metal can above chassis is wrapped in a cardboard or plastic insulator.

If that is confusing then ask me for some pictures tomorrow...Visual aid makes my point come across with at least a thousand fewer words. :D

No that makes sense. There are a few of the floating negatives on the chassis. This can however doesn't connect to any just the chassis and the wires leading to their various points.

So I've replaced the capacitors in the can and the image is still off. The top of the image seems to be above the viewable area. When I adjust the height the bottom two inches compact and are black. When I adjust the vert lin it goes to a flat line or with the old cap it wouldn't change at all just compress/cut off the bottom.
Is the all just the nature of this type of set getting a feed that nots meant for this screen?
Then there is the matter of the small gap in image on the left side.

IIRC you have not replaced the bumblebees and tubular ceramic caps in that set yet...Vertical troubleshooting 101 replace EVERY cap in the vertical stages first (no exceptions, total original capacitor genocide!), check for proper operation, then go after tubes and resistors.

See all the caps circled in my edit of your picture? If any of those are in the vertical stage or any vert capacitors currently installed look like them then the vertical will probably not work completely right.

Lytics can cause problems in the vertical (and sometimes are the only problem), but papers can be as bad or worse. On a set this old it is a miracle it works as well as it does now with those lousy old caps.

I already have all those marked for replacing but thanks.

Guess I'll see how it appears after that. I suspect it will be the same. Which if it is then so be it, could be far worse for a free set that's 61 years old

So I've replaced the caps and it actually preforms worse? The screen height issue is still an issue and now the screen flickers consistently.
I'm going back to the old caps before I stick more money into this.

Unless I'm reading the can wrong. I'm assuming the prong in the upper right corner to match the cap that is stamped as square on the can. The opposite prong as the triangle and the semi circle is obvi

Under the red wire is a triangle. Blue is connected to the half moon, as noted, and pin with no obstruction is the square. Outside perimeter tabs are ground.
Ed

When putting a cap in parallel to increase its value, is that just voltage or capacitance too?
Have a paper cap that is .047 with 200 vdc. Can't find a cap that low with a minimum of that voltage. Found one that .05 but not sure if two would cause a problem

Also, wtf is this? Pulled up a few times looking for replacement for paper caps. Do I just solder wires to the silver edges?

When you put capacitors in parallel, the total capacitance is the sum of the two capacitances. I think you understand that?

The voltage rating of the caps is not changed by putting them in parallel. So, for example, if you are replacing .047uf 200v with two parallel caps (say, two .022 uf) they must both be rated 200 v or more. If they are rated a higher voltage than 200, it doesn't hurt.

Capacitance is the ONLY value that adds when capacitors are connected in parallel. The voltage of a parallel capacitor combination is that of the lowest sticker voltage rating of any single cap in the parallel group.

Big space to separate topics:






If you want to combine caps in a way that increases the effective voltage rating then you have to connect capacitors in series...However that only works for a group of caps that all have the same capacitance rating (if not then the voltage will divide unevenly in ways that are a pain to predict). Also if you put capacitors in series the capacitance drops. which can be calculated for any number of individual parts wired in parallel by the formula: Ct=1/[ (1/C1) + (1/C2) + (1/C3) + ...+(1/Cn) ] where Ct is the capacitance of the parallel combo and C1 thru Cn are the individual parts that make up the combo. The ... and Cn mean you can calculate your result for a near infinite number of different caps of different capacitances.


Do NOT buy surface mount capacitors for replacing paper capacitors. Buy ones like these (which I use). https://www.mouser.com/ProductDetail...n1p2vhg7KKs%3d



good luck.

Roger that. I just can't find one with such a low capacitance. Are these bumblebees often hard to find a replacement? Closest I found was what ever this is

Oh so that a surface mount cap, yeah wasn't going to buy that amyway

Yeah, the one in your post #71 is a surface mount part. What is the capacitance and voltage of the original you are looking to replace, but having a hard time finding?

I'll get to those caps later. I'm taking care of the lytic caps first. Two replaced but on the third, which does have some damage, the image gets worse with the new cap. Reclip the old and it's fine again. The values match so I am not sure the problem.

Can you show the other end of the cap. I suspect VNP means volts non-polarized...Meaning you can't replace it with a polarized lytic (though you may be able to replace it with two wired in series in a special way).

Another possibility is that the original is leaky and that leakage is compensating for another problem elsewhere...

Both would make sense. The sams didn't have reference about VNP and you couldn't see the writing until removing it. The other end does have some damage.

Since both ends are rubber insulator I'm pretty sure that is a non-polarized...Most that style that are polarized have one end aluminum (negative) and one rubber (positive).

There are two ways you can replace it; order the correct non-polarized lytic or put two polarized lytics of twice the rated capacitance of the original in series*.
* For them to behave like a non-polarized cap you need to connect both positives together then connect the negatives to circuit OR connect both negatives together and connect the positives to circuit.

I'm going to have to run them in a series anyway unless I find a different cap source. Mouser.com has no polar but highest is 100 volts and this is 400 volts 10uf

Is it common for a cap to be in place but not listed on a Sam's? The .0068 paper cap centered does not appear in the pictured diagram or show in the list of caps with that value. Could the SAMS just be off and Zenith used a slightly different design? Aside from a bumblebee being a paper the SAMS has bee spot on.
Also I removed the cap to find it's value and later turned the TV to test a replaced resistor. The set's picture was noticably better while that cap was still removed. Probably from the new resistor but after I was surprised when I remembered I had not replaced that cap and it worked so well.
And yes I know that could have been bad and will not do so again.

Remember Sam's is usually only a snapshot of one random production run. Sets often had significant changes between and sometimes during production runs. Parts added, parts removed, values and or wiring changes, etc...Always evaluate what is there in the set for originality. If what is there is a factory part/connection then you can assume that is how it is supposed to be, but if the part is the work of an old tv repair by an unknown tech be prepared to doubt it (do note what the change was in case it is needed).