Here are a few pics of the board with the orange drops. Does all look right? I will also check below the chassis when I can flip the box on it's side one day soon.
http://i105.photobucket.com/albums/m...psc247068d.jpg
http://i105.photobucket.com/albums/m...psb0ec3702.jpg
http://i105.photobucket.com/albums/m...pse5c1bfbd.jpg
http://i105.photobucket.com/albums/m...ps7e9466cc.jpg

Thanks.

It looks like something's wrong with the Flyback, possibly burnt?
It looks like that red lead has been recently exposed at the end where it should be embedded in the tire.

I will have to try to get better photos listed of that area. I believe the wire is still attached and is part of the repair done in the 80's where something exploded in that area making a big paper mess and taking out the High Voltage, if I remember correctly. There are some trimmed pieces of the red wire sitting in the cabinet near that board. Probably from the repairman prepping the red wire ends for resoldering. Thanks.

those safety caps look correct (replacements for the ones known to go bad, there should be a sticker somewhere on the back of the cabinet documenting the fix).
if you look carefully you should see the word "special" along with the part number.

Looks OK, but the silicone rubber glob has been pulled off. MUST put a new glob, or there will be arcing (and a strong risk of RF burns to the hand anywhere nearby).

I think that flyback has an eye terminal on the windings; not embedded.

Charles

I see '72 date codes on some of the capacitors; so, this set was likely made in late '72 for the '73 model year. The tripler is an RCA replacement with an '84 date code on it. It's highly possible that it's still good; but, it could certainly be bad. I always replaced the original defective Zenith triplers with either NTE, ECG, or RCA(SK) brands and never had one fail; but, anything is possible. If this were mine, I'd yank that tripler and focus divider and replace the whole thing with an NTE526 tripler; which, has a built-in focus divider. Those original Zenith focus dividers would change value, causing poor focus; and, they'd also crack and arc/snap like crazy.

If I remember right, in the secondary circuit of the horizontal driver transformer, there is a resistor (1.5 ohms) and a small 15 volt electrolytic capacitor. Like the vertical chassis Zenith's, the cap drys out and the resistor burns removing a good deal of drive from the HOT. First sign of this is a foldover and a hot running HOT. Then a shorted HOT. I would always change those parts if they were original to prevent a headache. Also, but rare, a five watt resistor feeding the horizontal driver stage will open.
Looking at the flyback pictures, it looks like when the tripler was changed in the past the wre broke off the flyback and had to be resolded on. The flybacks, when failed, most the time developed a "hump" around the high voltage winding. That one looks good from the photos.
How do you tell a new tripler from the pictures? Easy! No silicone seal on the connections to prevent corona on any sharp bits to act as discharge points from the wiring.
And that set is HEAVY!!!! We called them 'Black Tops!" They always were upstairs which ment alot of cursing or FIX IT THERE!

What constitutes the flyback exactly? Is it the entire area between the 2 boards or is it the black area where the windings reside (or something else)?

The red lead actually had a piece of black electrical tape wrapping the area. It dried out and fell off exposing the area where the caulking/sealer is and the end of the red wire (since it was covered, it stayed of course cleaner than the rest of the wire shown).

The back of the tv has been exposed to sunlight for many years and the few stickers that are there are bare as whatever was written on them has long ago faded from UV ray exposure, unfortunately. I still plan to remove the bottom plate of the chassis to check the underside to confirm if there are any remaining caps there that were changed or are still the original(s).

1) Do you think the electrical tape that has been there since the repairs were done back in the mid 80's has done the job of the silicone in preventing the arcing?

2) Is the eye terminal, that you mention, visible in any of my photos?

1)Where do you see the '84 date code on the tripler? Not sure where to look.

2) Does the NTE526 tripled replace everything next to the horizontal output transistor that is vertical (the orange board and everything attached to it as well as the second board parallel to the orange board, etc)?

3) Is the focus divider located there too?

Thanks

I will have to check the schematic to see where these components are. If they are damaged, are they externally visible or internal?

It looks like a tripler retrofit was installed. If so, be happy. As mentioned earlier, the focus dividers (little white or yellow rectangles) mounted near the tripler would split open and hiss and then arc.
Can you hear a distinct "crackle" of the high voltage coming up when you turn the set on?

As I viewed the schematic, I believe it was probably the tripler that burst back in the 80's and repaired. I remember the repairman mentioned something about the HV and that back right corner was where the exploded remains of the tripler were. What is the function of the tripler exactly?

Have the original focus dividers been replaced here or are they visible in any of the photos?

I don't remember hearing any sounds at all when turning the set on but will check again.

The tripler is a device that contains a bunch of diodes and capacitors. It's function is to triple the voltage that comes out of the flyback transformer. The flyback outputs around 10 KV and the tripler bumps it up to around 30 KV. From what I can see, it looks like the seperate focus divider is still used.

Hey guys,

Does it appear to you that the tripler is not original in the photos below? One red wire in the back corner appears to have never been disturbed. I am also not sure, now, what exploded there back in the day but I do remember there was a lot of paper (like an exploded firecracker).
http://i105.photobucket.com/albums/m...psfcd19c6b.jpg
http://i105.photobucket.com/albums/m...ps31ecb9b4.jpg

Also, could this have anything to do with the no video problem? Just noticed this ground strap from the chassis not attached under the CRT. Thanks.http://i105.photobucket.com/albums/m...ps88cb59ce.jpg

Yes this tripler has been replaced. The giveaway is the "SK330x" part number on the side. The SK series parts were manufactured by RCA, and marketed as replacements for many OEM Parts. They published cross reference manuals so a technician could look up an original part number, and find the suitable SK series replacement. Sylvania/Philips (ECG series) and NTE electronics sell/sold similar lines of replacement semiconductors. Most independent TV repair shops used these universal replacement lines whenever possible, as they were cheaper and easier to get than OEM parts in most cases.

The red wire in the back corner of the tripler goes to the CRT anode. It wasn't "disturbed", because it is a permanent, potted-in part of the tripler module. A new tripler included a new CRT anode lead and cap in almost every case. The 3 other terminals on the tripler should have been covered with silicone rubber sealant when the tripler was installed, to prevent corona/arcing.

The original focus divider is still in place. It is the other plastic block looking component with 3 leads to the lower left of the tripler in your photo. The unused "F" terminal on your tripler is a focus voltage output, which indicates that the tripler incorporates an internal focus divider,, which isn't being used in your installation.

A capacitor is most likely what exploded and those white ceramic tubular caps were known to explode. When that happens, it can shoot pieces of foil and wax paper all over the place.

Since it was one or more of those white caps, then, it seems that the tripler was the only other component replaced. Would you agree? Still have to remove the bottom cover and see what may have been done on the underside of the chassis.

Also, any thoughts on the loose ground strap as a possible solution to the video problem? Haven't had a chance to reattach and not sure where to reattach exactly. Will try to pinpoint where it could've detached from. If anyone has any idea, please let me know. Thank you.

Those ground straps usually have a slip clip to go on the picture tube magnetic shield. I've also seen them ripped off of the CRT socket when someone was too lazy to replace a carbon trailed (arced over) crt socket.
Most likely the chassis was pulled and put on a jig for repair and the tech didn't see the ground when he reinstalled it.

As I try to find a few minutes here and there to do some testing on the set, today I managed to turn it on and listen out back for this distinct "crackle" of HV. What I did hear, and hadn't noticed before, was a consistent buzzing coming from the HV area, as best as I could ascertain by listening. The buzzing came up quickly after turning on the set. It can be heard from the back but not from the front. Should I try to pinpoint the source more closely and how can I do that with some tool (insulated auto stethescope/probe would be nice, right?!). I'm afraid if I put my ear too far in it may come back out slightly toasted. Is anyone familiar with this sound and whether it is normal or tells us anything about the issue. Thanks.

Just putting this out there again if anyone has any ideas or can tell me what this could be. Thanks.

That buzzing sound could be coming from the windings on the deflection yoke that are responsible for vertical deflection.

Sorry to dig up such an old thread, but I'm supposed to be getting a set just like this soon, and in my research, I found this thread. Just wanted to know if this set was ever repaired and what the problem was.

Hey guys,

Resurrecting my old thread for some sad news. I was never able to get around to repairing the old Zenith and life has gotten very complicated. We moved my mom in with us and are selling her house. Have no where to put the set and I don't want to just kick it to the curb so wanted to let the forum know that we would like to give it to someone who would want to restore it and possibly give it a new life. It's been really hard as we did want to try to fix it but the time was just never there. So if anyone is interested please pm me as soon as possible. Unfortunately, I think it would have to be pickup only as I think the cost and difficulty to try to ship this piece of furniture would be astronomical. I think I would need to post this in the classified section of the forum (as soon as I can figure out how and where) so that more members can see it. So anyone reading this let me know. And thanks for all those who helped in this thread over the years.

Here's a link to the classified listing of it if anyone's interested:

http://www.videokarma.org/showthread.php?t=272222

Lou, you may want to post on the ETF classified or in ARF. There are no doubt many New Englanders in road range of your location.

Sorry, not sure what or where either of these are if you could explain. Thanks.

Well, my son somehow managed to convince my wife to allow us to keep the set and take it with us when we move! So, with that in mind, is anyone still around from this old thread (or anyone new since) who can respond as to whether they would be available to help me in repairing this set as planned oh so many years ago? Thanks if anyone can respond please!

Re-reading through this old thread, that is from before my time, there was a lot of jargon in there that would probably be overwhelming to you.

Assuming you're picking up where you left off, the first thing to do is confirm that there's no high voltage: if you don't hear that static crackle when the set first turns on, then there is probably no high voltage.

Next you should double-check to make sure the circuit breaker isn't tripped. Push it in and power on the set again.

After that, the assumptions made here lo those many years ago are probably correct. There are several suggestions pretty much all of which boil down to two things:

1. Failed tripler, horizontal output transistor, or possibly flyback transformer. The tripler was replaced in the past but it could have failed again - they are a high-failure item, relatively speaking. The usual failure scenario in these sets was: Tripler shorts, which then causes the horizontal output transistor to short, which, if the circuit breaker doesn't trip to save things, will cause the flyback transformer to fail.

2. A lack of horizontal drive, meaning the signal that drives the horizontal/high voltage section isn't present.

By far the most common cause is the first one. The steps to track them down are all in the thread, but if you don't know what you're looking for it would be tough. Try this:

1. Un solder the wire from the tripler that goes to the flyback. Position it so the end is well clear of anything, and turn on the set. Hold the tip of a screwdriver about 1" from the end of the wire you just unhooked (don't touch shaft of the screwdriver, just the handle) and see if you get a little arc. Move it closer until you do. In most cases you should see a little spark there, indicating that the flyback, horizontal output transistor, and horizontal drive are all working OK and that tripler needs to be replaced.

2. If you don't get a spark or arc, and the circuit breaker isn't tripping after you reset it, it's possibly a bad horizontal output transistor but more likely the flyback is open, or you have a horizontal drive problem.

Check those things out and we'll help you from there. That's still the best TV ever made.

Thanks for your comments in this resurrected thread. I remember, although I couldn't easily find it on a quick look back, earlier in this thread that someone mentioned that if I reset the circuit breaker to see if it was tripped and then turned on the tv, that it might damage the circuitry even further (like you mention about maybe damaging the flyback transformer)? With that in mind, would I just approach the testing you mention by just following your instructions and nothing untoward should happen? Thanks again.

Well never say never but generally speaking if the circuit breaker tripped before due to a shorted transistor or tripler, it will trip again right away. Just don't go resetting it over and over. Once is enough to tell if it's going to keep tripping.

Does anyone have any leads as to who/where I might find any of these possible parts to repair the set, once I figure out which part(s) is/are the problem? Thanks.

They are commonly available here, on ebay, or your local electronics distributor. There's nothing unobtainable in that set. The flyback is the most unlikely but I recall others saying they have spares and parts sets in this thread.

The first thing to do is to check the horizontal output transistor for a short. Do you have a test meter?