Another mouth to feed!

[Zenith26kc20]

Here is the latest one! A Zenith 25NC38.
This one came from it's original owner and was in a home that "survived" Hurricane Katrina. It has a bit of moisture damage but appears in overall good condition! Watch out... here comes the ESR meter and then the variac!

[sampson159]

those are good sets!green halo is very slight.should provide an outstanding zenith picture.post more pics!

[Zenith26kc20]

Finally got the set in the shop. The convergence is hanging down (broken), 3AT2 missing, C139 is getting hot at about 20 line volts. focus rectifier is replaced by a stick diode, degaussing is disconnected and the picture tube is..... GOOD! Gonna try to reform the cap temporarily but I think I'll be stuffing a cap in the near future. Not as bad as some I have dragged home!

[zenithfan1]

Is that convergence yoke broken or just unclipped? Nice Zenith BTW.

[Zenith26kc20]

First, we have high voltage (at least RF on the flyback cap). It took replacing the dual cap and then nearly blowing it up. The voltage doubler was picking up a ground in the secondary of the power transformer. There is a black wire going to ground that, once lifted, the short went away and the doubler started working. I have to get a 3AT2 and see what happens next. The question is, what is that black wire. I thought it may be an electrostatic shield but they generally are grounded internally. Any thoughts?

[Zenith26kc20]

Oh, and the convergence assembly is now fixed. Zap-A-Gap instant glue (watch out with that stuff..... it's STRONG) and a bit of careful glueing pieces back together and it's fine.
No, no fingers stuck this time

[Zenith26kc20]

Here is the first screen shot of the Zenith I've been working on! It's rough and needs a lot of TLC but it's alive. Good scare on power up! Someone (not me) left the cap off of the 6bk4 tube. Talk about racket. I thought "now I gotta change the 3AT2 filament winding" but a bit of looking and we have no more popping!

[Zenith26kc20]

This past weekend I finally got the NC back up and running. A new yoke (thanks to damen and his friend) and C49, a three section electrolytic that opened up after the set was on about two hours. I tacked some tubulars underneath until I can remove and stuff the can. It looks like the color crystal is failing as color sync jumps out and I have to readjust the color osscillator coil to bring it back in. From the schematic, it looks like a small one will work as the crystal has very little voltage on it.
After that I'll finish the convergence and get some pictures.

[Jeffhs]

Originally Posted by Zenith26kc20

Here is the first screen shot of the Zenith I've been working on! It's rough and needs a lot of TLC but it's alive. Good scare on power up! Someone (not me) left the cap off of the 6bk4 tube. Talk about racket. I thought "now I gotta change the 3AT2 filament winding" but a bit of looking and we have no more popping!

Let this be a lesson: always look things over very carefully and correct any problems (such as, in this case, disconnected tube caps) before applying power. You are very fortunate the high voltage didn't go through the roof (or worse) with that 6BK4 plate cap off the tube, since this renders the high voltage regulator inoperable. That's probably why you heard so much noise -- it was quite likely high voltage arcing. Continued operation of the set in this condition could destroy the flyback, the 3AT2 HV rectifier or other components in the doghouse (HV cage). I don't know how common replacement flys are for your Zenith color set, but since these TVs are now over 40 years old, finding a replacement could be difficult if not downright impossible.

[Zenith26kc20]

It only popped for about a second. I keep my hand on the bench kill switch whenever I bring up an unknown to prevent "surprises".
I would have seen the cap off but the 6BK4 is very well hidden behind a hinged high voltage cage. In order to get to it the cage is pulled back and the tube is then visible. The 6C4 pincushion tube is even harder to get to.
This has been a fun set to keep going. It was someones daily driver for many years then it sat in a house flooded by Katrina. It didn't get wet but it sat in a swamp like envirionment for a few weeks until the owners came home.
Just imagine reaching over to get the 6C4 out and having the 6BK4 take a bite out of you (no HV bleeders on this critter)!

[Jeffhs]

Originally Posted by Zenith26kc20

It only popped for about a second. I keep my hand on the bench kill switch whenever I bring up an unknown to prevent "surprises".
I would have seen the cap off but the 6BK4 is very well hidden behind a hinged high voltage cage. In order to get to it the cage is pulled back and the tube is then visible. The 6C4 pincushion tube is even harder to get to.
This has been a fun set to keep going. It was someones daily driver for many years then it sat in a house flooded by Katrina. It didn't get wet but it sat in a swamp like envirionment for a few weeks until the owners came home.
Just imagine reaching over to get the 6C4 out and having the 6BK4 take a bite out of you (no HV bleeders on this critter)!

I said what I said about HV arcing only because you had mentioned "what a racket!" when the set was powered on. If it only arced for a second or so, however, that arc must have been quite loud.

I'm amazed that TV didn't get wet during the floods from Katrina. If the set was in a room that was flooded, I would expect the TV to be affected -- at least the cabinet would have been soaked, at least partially, and the finish damaged. Because the set sat in a "swamp-like" environment for several weeks, however, there could have been damage to the flyback and other parts of the HV system from high humidity. I suspect the one-second arc you heard may have been the flyback windings shorting to the core, although if this were the case the short would be permanent and should have blown the fuse in the cage. If the set works now and hasn't arced since, however, I don't know what could have caused the arc -- could have been any one of a dozen things.

[Zenith26kc20]

It's amazing to me to see how many things did survive in flooded houses after Katrina. I've even seen a 36 inch Sony XBR that did partially go under water (covered the chassis) and it is still playing. Big screens were the most damaged as the optics were ruined even tho their chassis still worked.
I hope my NC chassis settles down for a while now. It was a workhorse after the first repair. I find that sets that were laid up a long time generally give trouble after they have run awhile. This one appears to have been out of service a long time even before the storm.
I would be leery to run a submerged set but many people here still run them.

[AUdubon5425]

My mother-in-law was running a "submerged set" last time I was in her house a couple of years ago. She's in the Bayou Liberty area - maybe it was mostly freshwater there? I can tell you that here in St. Bernard I don't think anything still worked. Every portable radio and TV I saw on the trash piles had frozen controls from the saltwater.

[Zenith26kc20]

Salt water was pretty rough on a lot of things but a friend of mine has a very exotic SET amplifier that was in his house in Waveland, Mississippi and it went under salt water, got covered in sand and sat in the boarded up house 19 days until his return. He washed it out with distilled water and drenched it in WD-40 and left it in the sun for days. It still works today but is as ugly as sin now. Another weird going on is most of the A/C condensers needed the contactor and fan motor replaced and are still running.

[AUdubon5425]

Originally Posted by Zenith26kc20

Another weird going on is most of the A/C condensers needed the contactor and fan motor replaced and are still running.

I was going to do that and got talked out of it. Still have a new fan motor & condenser in my shed for the old unit.