Zenith Custom 23 Super H Chassis: FIXED
 

So here I am on the next one :) . Here's where we stand....

Did a basic recap of the mylars. Hoping that the filters were good, just because I get lucky once in a while on 1960s Zeniths :D . It's not proving to be the case.

Attached is a pic of what I'm getting on the screen at the moment, perfect sound, and I can adjust the picture to come in great with great sync lock, even if it's only 2" tall.....lol.

Two other things I need to point out. First, the flyback's plastic coating seems to have melted off, and is sitting in the bottom of the HV cage. Ever eat a DQ Dilly Bar, and one of the pieces of the chocolate coating comes off in the shape of the bar, kinda rounded? That's what the flyback coating looks like. It's not arcing, but wanted opinions to see if I can re-seal it somehow.

Second, is this really weird 3 wire disc cap. It says 87* on it, and to be honest, I can't ever remember seeing one like this before that needed replacement. It's cracked like dry dirt in the center, so I'm assuming that it needs to be replaced. But with what?

NOW.....yes, I know that I'm going to have to do the filters, as much as I dislike doing them :D. That's next. Wondering if anyone has any thoughts on the rest?

Tim,
Whats the chassis number? I can send you a schematic if its a pre-66 set. You will need it to figure out the disc.

The 87-disc is probably a dual capacitor but not quite an "integrator" and is most likely your trouble. It can be built from 2-3 separate caps/resistors. '
Also, Zeniths of this era had issues with open height/linearity/hold pots.

As for the flyback, replacing paper caps in and around the damper-boost circuits off the fly will cool it down, as it probably got hot before the vertical crapped out. Its all related. Long ago I fixed the arc-trashed flyback in my RCA CTC12 with a brush-on coating by GC, http://www.alliedelec.com/images/pro...S/70159781.pdf

DAve

It's a model F2737E, dating it to 1961.....

The 87- is probably the problem. There is a color dot on it
that gives you the part #. Example yellow dot = 87-4 etc.
Use resistor color code...... If you cant get NOS look in the
SAMS they often have the break down of them.
If it were a Zenith double disc cap it would have a 22- part #
and usually be blue or tan.
The 87- integrators were high failure so start there. Must
have put in 100's of them in the good old days.

73 Zeno

Good eye! and its in the feedback loop of the 6EM7. Sams 525 lists it as K2, replacements by Centralab PC-408, aerovox PA-764 or a Sprague V-14. I did not check the chassis 16F21 factory manual, but probably no clues there.

The equivalent circuit looks like a few series resistors with capacitors from each junction to ground. An RC network optimizing shape of the vertical sawtooth for linearity, it was simply designed to save labor and space.

Any guesses as to what those values really are, but a look at an RCA CTC-11has a 6EM7 and similar values. The CTC 11 circuit has two 680 pf to ground on either end of a 47K resistor in the feedback loop with a 100K on plate side and a .0068 mf on the grid side. Sub in those parts for the "K2"

Interesting development here.

I parted out a '67 Zenith color set that was toast, in hopes I'd find one of those 87*'s, and sure enough, I did. But I also found something else pretty interesting.....a blue cap with a similar 3 pin configuration and a VALUE on it!!!

As you can see, it shows a "2 x .001 10%" on it. Using the center pole as a mutual ground, I tested the two outer ends, and it is exactly a double .001 cap.

Now, for the 87* , it tested at .00189 on both ends, or .002 each side, for all intents and purposes. What the devil the "87*" means, I have no idea, but there it is.

Now, I'll sub in the 87* from the other set, into this one and see what happens. I don't have any .002s on the shelf, and I hate putting in four .001s.

Oh, wait a minute wait a minute. I doubled back and re-read this, it's been a couple months. So is it NOT a cap? I'm confused.

THE 87-* is the integrators. The color blotch on it is the 2nd part
of the part##. If one has a yellow dot its an 87-4 green dot is
87-5 etc. Use the resistor color code.

22- numbers are for most Zenith caps. The double caps I remember
were .001 They are usually light blue. I NEVER replaced one.
If your cans are still OEM they will also have 22-**** numbers.

The #1 vert problem on old Zeniths is the integrators ( 1 or 2).
#2 is electrolytic in cathode of vert. output. Its prob in
one of the cans. #3 is other caps in vert feedback loop,
from the output plate to the osc grid. That is 90% of
non tube failures.

Good luck

73 Zeno:smoke:

Okay, but what *is* an integrator. Is it a capacitor/resistor? Is it just a twin lead cap as my test would have me to believe?

Basically, I need to know what makes this thing tick, so I can substitute modern replacements. From what you're telling me, this seems like the 1960s version of the Philco bakelite block condenser.

IIRC inside is 2 resistors in series. A cap goes to ground
at each end and at the junction of the two. All the
values are the same.
I was right ! I duck duck goed it & found this....
http://www.boxcarcabin.com/integrator.html

73 Zeno:smoke:

When replacing, what would you use for wattage on the resistors, and voltage rating on the caps?

IMHO 1/2 watt resistors & 600v caps. May want to go 1kv
to play it safe. Disc caps should be OK.

73 Zeno:smoke:

After replacing that suspect integrator and doing the filter caps, there's no change. Here's a shot of where I'm at now.

I've been advised that the next step is a vertical output transformer, so I'll be giving Moyer a call this week....

You gunna test that transformer first ?

Maybe test the voltages around the output...?

Check for open V-hold-Height-Lin pots...?

I don't have a Sams for this particular set, so I don't have any reference as to what anything should read. Honestly, I'm okay with throwing a few parts at it, as my plan is to make this set my "daily driver".

If the vertical output transformer is shorted, unplug the convergence panel. I had both of my Zeniths (an M and an N) chassis fail identically. While waiting for a transformer, I could use them and get full sweep but outer convergence was terrible. Try to get a Thordarson transformer. They seem better built. I replaced both of mine with Thordason.
Is it the picture or is there a slight keystone to that raster? Keysone means yoke. Look for green corrosion on the youke windings. We changed a lot of Zenith yokes tears ago also.

This one's a black and white, though :)

There is a slight keystone to the raster. The picture comes in clear and locks in sync, but it's only as high as the shot that I posted.

I always consider service literature a better thing to throw money at. I'd rather KNOW I need some expensive rare part and then get it, then waste my money depleting replacement stock for somebody down the road that does need it only to find out my set really did not need said expensive rare part and probably never will.

When you work smart you become a better tech, and spend less money replacing good parts.

True. But at this point in the game, I'm trying to accomplish two things. I'm trying to broaden my knowledge, and I'm trying to get the set working. Many times, one comes at the expense of the other.

As with electronic automotive components, substitution with a known good component can yield the simplest diagnosis. More expensive, yes, but I'm okay with that.

Is that the 23" Zenith that uses the 110 degree CRT? All Zenith's 23's, after that used the 90 degree CRT's. Large neck.
I'd put my money on a open vertical winding in the yoke, especially if it's the 110 degree yoke.
If it's the 23", 110 degree model, it's an odd-ball. IIRC, they only made one year of them. There must've been a reason! :thumbsdn:

Picture tube is a 23ZP4. Looks like a 90 degree to me, it's a BIG HEAVY tube.

Is the yoke a 95-1610? If so, I have changed a few of them. It goes to a Stancor DY-13A. If you remove the yoke from the neck, you will see green corrosion on the windings. This seems a problem with some sets.

IIRC, that's the first year for that CRT and the big heavy front glass panel.
I keep forgetting those sets are 50+ years old and subject to large component failures.
Remove the CRT and inspect the yoke windings, as suggested. Take resistance readings of the vertical windings. They should both be alike. Around 15 to 25 ohms. If there's resisters across the windings, disregard them. If the winding is open, you'll just read the resisters.

I'll have to do that when I get chance, but I went to take a picture of the yoke, just to show, and I noticed what appears like a burn mark in the plastic cover. You can see it in this picture as a white spot, but in that white spot it appears to be melted.

Hm.

No visible marks that I can see, but again I'll have to pull it anyway. Good thing is that Moyer does stock the yoke.

Fixed!
 

It was the yoke. Replacement came in from Moyer, and I installed it right away. I'll have to dial in the rest of the picture adjustments tomorrow when I can get a flat bladed screwdriver that's thin and about 8 feet long to reach the linearity and height controls on the chassis ;)

But tonight, gentlmen, I get to watch TELEVISION! :bigok:

Yoke was actually a 95-1654, which crossed to a Thordarson Y98. Same yoke also fits 95-1768, 95-1825, 95-2093, and 95-2383, with one exception.....there's a white wire that goes to a 1 megohm resistor that isn't used with my set. Didn't see any corrosion or really anything noteworthy on the inside of the old yoke.

Got it dialed in nicely. The Brady Bunch looks pretty darn good :)

Put the back on, and I call this job done :thmbsp:

Very cool! :smoke:

The pattern looks wedge-shaped. How about the deflection yoke?

Sorry- for some reason didn't see all the previous posts!

Well, your diagnosis was spot on! :)

Boy your not kidding! I gess the high voltage here is whats causing it to be so tall now, being so close to the substation our outlet reads 137v.

But the height it too tall now and the picture has a hourglass shape to it now.
Other then that I watched a 2 hour movie on it when I first got it home and its very watchable. and steady.

I noted the million foot long screwdriver was needed to get at the height.

Any idea how set the picture? I don't want to mess up your good work.

http://i1118.photobucket.com/albums/...ps9d84c721.jpg

Honestly I don't remember where the height control of the set even is. I set it up on an indian head test pattern after I got the yoke done, and it looked pretty good.

If the height control needs a super long screwdriver, you may need to pick one up or borrow one, I'm assuming that the control can't be reached safely otherwise. But I'm guessing that you need to dial the vertical linearity back in slightly, as the stretching appears to be at the top. I'd go with that first. Linearity, then height. A couple screwdriver turns will bring that in.

With screwdriver pots, you're not going to really mess anything up. Just turn the pot slowly and note the change on the screen. I've found the most effective way of doing it is with a mirror in front of the set, so you can see what you're actually doing.

Post a picture of an actual image on the screen, as in a screen shot. From your crosshatch shot, it really doesn't look bad. Most of what you're seeing probably won't even appear on normal programming. Crosshatch is mostly used for color TV convergence. The question is, how does the picture look?

For extra long screwdriver make it out of a knitting needle.
Xlite used to make a foot long that worked great on Zeniths.
Also made 2 foot 1/4 inch & the next size ( yellow handle)
with magnets & a 2 foot phillips for the Jap sets. Watch for them
on TV shop clean outs.
I still have them but you will have to pull them out of my cold dead
hands..........

73 Zeno:smoke:

One thing I have done in a pinch, is to slip some nylon tubing similar to aquarium hose over the shafts of the controls, leaving it long enough to reach the back of the set and twist that. Then it can be as long as it needs to be and you don't need to constantly line up screwdrivers. Make sure you wait for the TV to be really warm (on for greater than half an hour) before attempting this adjustment or you will be doing it over and over again. Also, if your line voltage is really 137V, there is a problem with your wiring (probably a loose neutral), and you should get that fixed right away. 137V is way too high. If you actually meant 127V, then I guess it's within tolerance but still not so good.
Some TV sets have multiple taps on the power transformer for high and low line voltage - if yours is so equipped make sure it's set to the 125V tap.

If your voltage really is 137! A complaint to your power company is in order. The pole transformers have multiple taps to adjust the viltage, usually.

All the controls are on the front so its very easy to look at the screen,
Also the voltage checked again, It is now 131 But at night its 137. And around 2pm it hits 124.

I gust got a new screwdriver i'm gonna watch some honeymooners before i adjust the leanarty.

137 volts is totally unacceptable - try a second meter to make sure it's true and it isn't just your meter reading high. That's enough voltage to shorten the life of everything electrical in your house not to mention jack up the power bill. The relationship between voltage and expected life of things like tubes is not linear, you will get a much shorter life with such an out of spec voltage.

Ok my old meter only goes to 130vAC
And it is pegged.

And the cheepy multimeter with the leads stuck right into the outlet says 133

Absolutely true! While amperage goes up on a linear scale with voltage, Wattage and heat dissipation go up by the square of volts times amps.
I sure would not run that vintage set any more until the line voltage is within spec.