Attempting first project - Some questions if I may
 

Disclaimer: This is going to be some dumb/newbie questions, so if you're not patient this is not a good thread for you, lol.

OK so after two years of acquiring sets I finally am getting around to recapping and retubing my first set. A Zenith b/w table top. I've been reading here, watching videos from shango and Doug, read the antique radio guides, etc.

These are my questions (based on the pictures below).

1.) There are two electrolytic cans that have three terminal leads each with different values. After scouring the net I am guessing these types of twist lock style cans are no longer produced. I have two NOS exact part # Zenith replacement cans. I understand the point is that it is not a matter of used/unused it is a matter of time drying out the electrolytes. But really, if I use these, will it be the same result as not even replacing the old ones?

2.) In the photos that show under the current can already installed, I noticed the electrolytic capacitor only has wires going to two terminals leaving one unconnected. The schematic shows all three having connections. I have had this set on before and it worked as is. So what is up with this? I am not good at reading schematics but it shows that particular empty terminal supposed to be going to near the horizontal hold. So confused.

3.) Do these old cans just twist off? It looks like I will have to break the old one somewhat to get it out.

4.) The picture with the tape on the tube with a grounded wire to the chassis. What is that? I discovered that when I removed the plastic backing and it looks like someone rigged something up there.

5.) On the electrolytic marked "2407031", I have a nice new electrolytic for this one but I noticed on the right side it looks like there are two wires going to the + side. When I solder in the new one it is an axial style. Should I just make sure both of them are making contact to the new lead?

6.) Lastly, please look at my paper/film capacitor assortment. Are these the right type? All the values are matching the old ones I just didn't know if they are acceptable types. They are going to replace the old wax/paper ones.

OK, if anyone is bored/feeling charitable please feel free to answer these questions.

PS, anything to help me not get shocked before I begin? Nothing is too obvious for a beginner. The set has been unplugged for over a year.

Thanks!!!!!!

(6) - Yes, suitable types. The only caution would be if the voltage ratings were lower than the original (they are most likely OK).

(5) yes, just connect both wires to the plus side of the new one.

(4) The conductive coating ("dag") on the outside of the tube MUST be grounded. This way the tube itself acts as a capacitor to filter the high voltage supply. If it's not grounded, the dag can charge up and arc to other things. It looks like someone fixed a loose or broken ground this way.

(3) and (2): Someone else more familiar should answer

(1) both time and temperature affect the degradation of electrolytic capacitors. So, the NOS might be better but still not good. Safest thing is to replace with new, especially if you have no way of testing them. It takes an old-fashioned tester that applies sufficient voltage to see if they are leaky. A modern low-voltage capacitance meter will not detect this.

PS: after a year disconnected, your only risk of shock is static from scuffing your shoes on the carpet. However, once you do fire it up, it's good to discharge both the lytics and the high voltage after you shut it off and before you go poking around.

Of course, don't do any work while it's plugged in. It's a good idea to UNPLUG the set (not just turn off a power strip) in case it is a hot chassis set (no power transformer) or is a transformer set that happens to have a short somewhere.

I appreciate your reply. I will re-read it when I get home. Just quickly though with regard to the "DAG", now that I understand what it is, the coating is worn off in several blotches of the tube. Would it be prudent that I re-coat these areas (if that is even possible)?

Are you sure it's worn off, or could it be deliberately not applied in those areas? It should not be applied too close to the high voltage connector because of the possibility of arcing. (Of course, what is there should be contiguous so it's all grounded.) In any case, it's OK to wait until you have the set running to see if there is any problem. Aquadag (the full name) can be purchased and applied easily, but I wouldn't bother until you're sure you need it.

First thing is change the caps ONE AT A TIME ! Then recheck the
set & see if anything changed.

1) those NOS cans are OLD ! By the 70's they packaged them in just
plastic, not boxes. Since the set is running you may want to do them
last in this case.
2) it may be a subbed cap & there is another one hung in under there somewhere.
3) most Zeniths twisted 2 of the lugs & soldered the other 2 so breaking
off the twisted ones it will come out easy. You may need a very hot
iron such as the old classic Weller gun.
4) The CRT wasnt grounding good. Someone moused it to get by.
The GND is made either with a set of finger or a coil spring on the bottom.
Some use a very long, small spring across the DAG. If the DAG is chipping
off it can be replaced. Symptom are diagonal dots in pix, bad sync, sometimes hissing, sparkles & ozone smell. Can also radiate & bother other TV's radios etc.
5) not sure what you mean here.

Safety ! The most dangerous place is where the AC comes in. I never
heard of a tech dying from a TV HV shock. I got them once a week for
40 yrs. The filter cans in most sets will bleed off fast. The HV will stay
charged a LONG time with a tube rectifier. Avoid the base of the HV
rect tube & anode lead. If you discharge it it can build back up to a
lower level so discharge several times over a few minutes.

BTW Put up a few under chassis & chassis pixs & chassis ##

73 Zeno:smoke:
LFOD !

Well I did notice it is not applied near the high voltage connector but I was thinking it was worn off due to the unevenness of it all. Toward the top it's chipping and peeling. After I recap it then perhaps I will see where I am with this aspect.

Thank you for the help. I am working on setting up a work area in the cellar then I can take more pics as I go. I don't want to open the set up again in my apartment as it is generally very dirty and crud always falls over the place.

No need to remove the FP cans from the chassis....Just disconnect the positive terminal leads from the can and it will remain electrically dormant and preserve the original above chassis appearance.

I think I understand what you're saying. Leave it alone, disconnect it from beneath and put the new capacitor underneath. Neat idea. I have also read about rebuilding them and stuffing the new ones inside.

PS...If I forget the NOS Zenith stuff in the picture I will need the following:

1) 150uf-350v, 100uf-350v, 200uf-25v

2) 4uf-350v, 10uf-400v, 20uf-25v

I have been looking at all the major sites they don't seem to have capacitors with these three values each in 1 can. I was looking at that thread where the can went through the roof so I may want to avoid using the old and dried out NOS stuff after all.

I'm finding that out now. I will have to pick up something more heavy duty for desoldering. For the normal soldering of the paper caps will a 30 watt soldering iron from Harbor Freight work? I seem to remember reading somewhere 40watt is the normal minimum.

For the most part, having 3+ sections in 1 can is something that died with FP twist lock style cans...It is fine/normal practice to use 3 individual caps to replace one 3 section twist lock. Most twist locks have the can as the common negative to each section. Some capacitance values like multiples of 2,3,4,5 are not made anymore and have been supplanted with 2.2,3.3,4.7,etc. You can fudge the capacitance values a decent bit and be fine. The original parts often had +100%/-50% capacitance tolerance so anything close in value capacitance wise will be fine.

Voltage you can only fudge upwards...The voltage rating of a cap is the max input voltage it can take without going bang(!)...If you replace a 150V with a 200V part the 200V can take more abuse before going bang. If you replace a 150V with a 50V the 50 will probably have ~100V on it and go bang quickly.

For the caps use
1) 100mfd & a 47mfd in parallal 450V
100mfd 450 V
220mfd 50V

2) 4.7MFD 450V
10mfd 450V
22mfd 50V

Thats all using modern values & a little extra on the voltage. Best
way to change is leave the old can in, Cut off wires & use a terminal strip.
Mount the new stuff close to the old ! Here is the style strip.

https://www.radioshack.com/products/...terminal-strip

73 Zeno:smoke:
LFOD !

Not too long ago I discovered that Mouser carries solder lug terminal strips by Keystone. I was surprised to see a vintage type of part there.
They have many versions with different number of lugs and in different arrangements. I've also gotten them from Radio Daze.
https://www.mouser.com/ProductDetail...HpkXpfvzp08%3d

A little hard to find on Mouser, search under "Keystone", terminals, lug terminals, terminal strips, solder type.

One of the first things you should do is clean the chassis. Some of that dirt may be conductive and lead to problems. You can use compressed air if you are careful. Don't hit the speaker or the DAG with high pressure air for instance.
Another way is using a vacuum cleaner and a soft brush (paint brush). Don't suck the Dag off the CRT.
A limited amount of window cleaner can be used but don't go near the tube numbers. The tube numbers can sometimes come off if you touch them.
It would be better if you worked on some radios first to get the hang of things.

30-40 W will do for most things. Things soldered to the chassis may take more, maybe 60W, but you don't have to remove the metal cased caps anyway most of the time. Also if a component lead is soldered to the chassis you can clip the lead near the old part and splice the new component lead to the old lead, no need for a big iron.

The cheapest iron at Wallmart will be fine for most PCB and light chassis work. If you can find a 75-150W cattle prod iron, those are awesome...You can make a chassis ground point wherever you want, normal terminals melt instantly, you can unsolder shield plates that are joined with solder easily, etc, etc...Joy to work with...Till you accidentally melt something plastic (the small ones can do that too).

It's funny you mention that, I did just that! A lot of rust came off, chassis is now looking good.

I've discovered paper caps are pretty easy and straight forward - when there is enough room to work! Some of these caps have no lead length and are behind several layers of resistors and other parts. I guess the engineers didn't intend for anyone to be recapping 50 years in the future. I also have several books from the 60's and 70's and capacitors are never mentioned. I guess this is a very modern thing we have to do.

Thanks for everyones help. I will have about another 6 questions soon in case anyone else will want to answer and help out. Cannot wait to get done and turn on the TV and see if it works, lol.

Note: when cleaning the above chassis take care not to leave any rust, dag flakes, solder splash, other conductive stuff on those above chassis terminals... I've seen dag flakes burn up, and I've seen power resistors burn up from a solder blob short (that I made resoldering stuff in the HV cage). Those exposed terminals are great for troubleshooting till conductive crap lands on them...Then things go downhill fast.

By the 60's most 'paper' caps had mylar in them(as part of the paper dielectric layer) or were really full mylar caps. Most 60's and newer sets don't 'need' the paper caps changed since the mylar prevents leakage...Granted the paper/mylar sandwich types tend to drift in capacitance as the paper degrades which can be an issue.

Mid 50's and older sets (late 50's early 60's was the transition to mylar) used full paper dielectric caps and lit from the paper cap era does warn of bad caps...If you do 50's sets and know what stock caps and soldering look like, then you'll find many 50's sets had several paper caps changed when close to new.

Sets ~1964 and newer I don't change anything but the lytics unless I have confirmation/diagnosis of cause of failure.

oh, wow so what am I recapping then? This set is from the late 60's or early 70's. I assumed it was customary to swap out all the capacitors with any old set. By the way, I should be more clear with my terminology. I think I am using the wrong term. When I say paper caps, I think they aren't really paper, more film drop type. I might open this thing up again soon, I will take some pictures. I am trying to come up with a game plan for the electrolytics currently.

It is usually customary to state more specifically what you are working on (model) and generally make each thread about that item.
Some of us here online are a bit rusty reading minds.
The first analog commercially successful TVs come out about 1939.
In the US analog TV broadcasts stopped in 2009, so that's about 70 years that analog TVs were produced. What "vintage" is depends on ones definition, a lot of times on Craig's list anything before 2009 is vintage!
Tube set production ended approximately in 1970, that's about where I would draw the line. However some would put it earlier.
Tubular caps progressed through the years from paper dielectric (many times soaked with oil) in a cardboard tube sealed with wax to paper dielectric in a molded plastic case, to paper plus plastic film in a plastic molded or epoxy dipped case, to film alone in a dipped epoxy case, etc. Problems arise because the paper will degrade, molded plastic cases crack and expose the insides to the environment. Probably other things happened also. Some capacitors in the mid 60's may have still used paper.
So if your TV was made in the late 60s some of the tubulars are OK, it depends on the construction.
Electrolytics before 1980 I would replace.

This TV is a 1971 Zenith Chassis 14b38. Definitely a tube set. There are absolutely no viable newly manufactured can capacitors for sale that will work so I have decided to go the 'restuffing' route.

You're a bit off. 1975 was the year that most of the major brands killed their last tube/SS hybrid chassis. The GE Portacolor (lasting as a production tube product till at least 1978) being the major exception (along with some small/foreign made names). If you are arguing from an ALL tube (no tube SS/hybrids) standpoint then you're probably late...Hybrids depending on how you define them date from the beginning of the category of PN junction you classify as SS to at least the late 70's.

I have some ~1964 Zenith sets still going fine on their original tubular caps...Shotgun recapping tends to be frivolous in sets past 1965...At that point, it is better to troubleshoot the problem.

I was speaking in general approximate dates for the most part. I didn't want to get bogged down in exceptions and what different manufactures did at different times. I know one of the earliest solid state TVs came out in 1959, Philco Safari, but that's an exception.

So the fact that I am missing this wire, and there is nothing subbed in as Zeno suggested, should I just run some wire and connect to the new can I will be rebuilding? Picture shows from the Sam's how it should be, running from the area where the horizontal hold control is to 1 of the terminals for the larger electrolytic. My situation is that there is currently no connection, no wire, nothing, just empty terminal. What is the consequence of this, just no horizontal hold function? I'm not sure why it would be set up like this.

Often times back in the day a tech would replace one section of a can (when just that section died) by disconnecting the wire to that section's positive terminal, deleting the wire and adding a new cap on the far end of the deleted wire. Look at the hold control (and any points connected directly to it by wire) odds are a newer replacement cap was connected elsewhere by a repair tech.


If the blank terminal appears to never had solder added to it then maybe it was not connected due to a production change or factory wiring error (yes I've seen Zeniths with factory wiring errors). But if a wire was soldered on and removed then my first paragraph is the likely scenario.

Without the schematic, it is hard to definitely say what lack of that cap would do. A lytic is normally for filtering not RC frequency setting. Odds are without it there would be more noise in the circuits it is on...Sometimes that leads to major issues sometimes only minor ones...Zenith sets have a reputation among repair techs of being able to do a damn good job of feigning normal operation despite some major component failure that normally would take out other brands.

OK thanks for the advice. When I open up the back again soon after rebuilding the cans I will take a look.

See if the old cap is original. If it is or its an OEM replacement
it will have 22-#### on it. Also a 4 number date code & 3 number
EIA code sometimes run together. See if the 22-#### matches
Sams. There may be a production change also BUT I did a lot
of cans on these, enuf to stock them & dont remember one.

73 Zeno:smoke:
LFOD !

I will check this out when I open it back up. I bought a replacement NOS can before I decided against chancing it with dried electrolytes. So when I rebuild the can and open the set back up to install it I will check what you said, take some pictures to post here as well because I will want to rectify any potential mistakes and that seems like a potential problem.

Incidentally where do you guys pick up your hook up wire? Seems like a dumb thing to ask but I am looking around for some 20 awg, solid, 600v, high heat, and with good insulation. Maybe it's hard for me to find because I don't need 100ft or more I'm looking for something inexpensive. I need it to rebuild the cans and so even a 25ft spool is overkill.

Your probably going to have get at least 25 ft.
Are you sure you want solid? Stranded can be used more places, like where some movement is expected.

I'm not sure about anything, I'm literally an absolute beginner. I'm just following the instructions below and trying to get my set working again after over 2 years.

Does this look remotely correct?

https://www.tubesandmore.com/product...oth-cover-600v

Luckily I have been reading here and studying a lot. I am glad I figured out about Kester solder before I used the lead-free stuff I bought from Harbor Freight.

Capacitors arrived today from Mouser, once I prepare the new can I will try to power up.

Oh, I see what you are doing now.
I was thinking you wanted it for chassis wiring.
For the capacitor re-stuff I would use bare solid wire, if the leads on the caps aren't long enough. Then, where needed, use heat shrink tubing for insulation.
To get the bare solid you could just remove the insulation from any solid wire. Use could also buy bare wire, often called buss wire. Cloth covered wire wasn't used much in a set as late as yours. Plastic covered wire is cheaper also.
Solid wire is OK for going point to point on the chassis, like from one tube socket to another or a terminal strip. Stranded should be used for thing like CRT sockets, separate speakers and separate tuners. Stranded would be OK for point to point also, that makes it more versatile. Solid is slightly cheaper and is easier to get into a terminal hole so the manufacturer used it for point to point.

I've bought wire from All Electronics. Modern wire usually doesn't have to be rated for 600V like tube electronics often does.
https://www.allelectronics.com/categ...e/cable/1.html

Thanks for taking the time to explain that. I understand what I need now. That's exactly what I was hoping to read. Now I just need to order it and then get to work on the rebuild. Can't wait. Thanks again.

I finally got around to tackling this project. I simply cut out all the old electrolytics and soldered in the new ones. My beginner soldering job was kind of sloppy but apparently good enough for the electricity to pass through. I didn't even bother to rebuild the can. I was originally under the impression I would be cutting out ALL the capacitors which is why I found it so daunting. I was under the idea that film capacitors should be replaced. Set has been on for about 2 hours, no problems. During the first 20 minutes picture was occasionally jumpy. I guess it either wasn't warmed up or the settings weren't adjusted properly. This is a 1971 Zenith. Speaker is starting to get tinny, don't know where to go for that problem.

Looking good!

Thanks so much!

I have about 5 consoles waiting to get started on. Would the electrolytic replacement procedure be the same on those or should I get more practice with table tops before moving on to the consoles? I've got two 13" Zeniths I can do next as well.

At the shop we used the wire from a junked Zenith ! Most of it was
braided & tinned, rubber coated followed by color coded cloth. They
WAY over did it ! No one else used has high a quality hook up wire
that I remember. Most used solid wire & it easily broke off over the
years from heat or getting nicked by dykes.

73 Zeno:smoke:
LFOD !

If the bias voltages are good in the audio section, check different fine-tuning settings to see if any improve sound...If none are better tune for best pic then adjust the Buzz control for best sound.

The main difference between console and portable Zeniths is that the consoles have bigger chassis with more parts and room to work.