1960 Zenith B&W Console estate sale find - new project - Page 2 - Videokarma.org TV - Video

Tube TV · #16 08-18-2019, 02:08 PM

To me the picture tube looks good, it does not have the ugly smearing that is there when a crt is weak. How far did you have the brightness control turned up when you took the picture?
Usually the smearing increases and the focus drops off the further the brightness is increased, and when this happens the interlace is not too visible.
Probably bad caps or resistor drift in the IF or video ciricuit causing the focus issue.
Considering that it's running on the original caps that isn't a bad looking picture.
Those bumblebee's are likely to be dead .

joe111671 · #17 08-19-2019, 05:12 PM

It doesn't have the smearing, but the bright areas of the picture don't have much detail. The scan lines are still somewhat visible in bright areas. I had the brightness & contrast both about 2/3 up, it has plenty of reserve. I'm going to replace the electrolytics for sure & see if that helps. I'm willing to put some effort and money into it as a learning experience, but it doesn't need to be perfect, as I'm probably not keeping it (I like the other set much better). Plus it has a cataract so it will never make a perfect picture anyway.

Tube TV · #18 08-20-2019, 11:09 AM

Well, it's watchable that's for sure. The crt might wake up more after it's ran for a while. It probably has not seen much use since the early 1980s
If I were you I would change the bumblebee caps while I was at it, and those white ones as well. The bumble bees are the worst for cracking and leaking.
The caps with the brown/orange finish that look like orange drops should be alright, if you wanted to do the bare minimum recap.
I have tested many of the old orange/brown caps over the years and they seem to stand the test of time.

joe111671 · #19 08-21-2019, 06:14 PM

I can't wait till it's safe to run long enough to see if the crt improves! I don't care so much if it improves or not, as much as being able to sit back and just watch it for a while. Interesting that you mentioned not being used much since the early 80's. Every single old set that I've gotten so far, I wonder how long it's been sitting, why it was retired, why they kept it, if it worked when it was put away, if they thought it would be wanted someday...

Are there any bumblebees / white caps that pose a threat to other components, the way a filter can? I ask because if some of them pose no harm and still work, I might want to leave them in just to learn how this stuff works if/when they fail. Like the cap that was causing the vert to run 1/2 freq. When I was adjusting the v-hold, I noticed that if I turned it way down, there were three images that locked in, as if it was running at 1/3 freq. That's what made me study the Sams and test caps near the v-hold control, and it turned out to be right there. So I learned something there. Now if it's wiser to just change them all, that's what I'll do.

Electronic M · #20 08-21-2019, 08:34 PM

Every bumbelbee is a catastrophic threat. When they fail they sometimes explode spraying conductive foil all over...That foil can short anything and damage anything. Best to just change them all.

joe111671 · #21 08-22-2019, 07:56 PM

I had a feeling that would be the case. I have a list of electrolytics to get, so I better figure out what else I need and get some caps & get busy! And thanks for the tips on where to get them, Tom.

I try to stick to one thing at a time, but now there's really nothing to do with this one till I get caps, so on to the other Zenith from the same estate sale for now.

I didn't know if I'd see it work or not. When I got it, there was a brightener laying inside, but the crt was connected normally. The 5a fuse was missing, and the brackets that secure the crt to the flyback housing were partly unscrewed, it's like someone was working on it and gave up. Plus it was filthy so that made it look more hopeless.

I cleaned it, jumped a fuse in, put it in series w/ a 100w bulb for about 30 minutes. Nothing got hot, the light bulb & tubes were dimly lit so I plugged it in and it just worked. It needed the same cap in the vertical as the other set. The picture is nice on this one.

joe111671 · #22 10-23-2019, 05:54 PM

As planned, I started working on the other Zenith. After it ran for a total of maybe 20 minutes, the picture started blinking now & then. I spotted arcing at the base of the damper tube. I subbed in the damper from the Zenith with the cataract and it took care of that. I was concerned that the set was causing the arcing, so I put that damper in the cataract set and it arced there, too. So I replaced that, made a list of all the paper & electrolytics that it has and placed my order.

Two vertical caps into it and the horiz output tube failed. I subbed the one from the cataract set and finished the recap, and it's been working pretty well. I've probably put about 16 hours on it so far and it's been very stable, I got the geometry as good as I can, but the vert linearity has to be all the way up to get it like this, and there's a horizontal line in the middle that's brighter than the rest of the raster. It's not visible in the picture, but it's definitely there. It doesn't show up till the set warms up and the vertical fills out, which takes about 5 minutes.

It doesn't bother me, but is this a telltale sign of something that needs attention so I don't damage anything?

I'm happy with it as is and I want to put the chassis back in the cabinet, but not till I'm sure it's good to go, as I don't want to pull the chassis out again for some trivial thing that I should have done.

nasadowsk · #23 10-23-2019, 08:20 PM

Horizontal line, or vertical line? A vertical line, a bit to the right (or was it left?) of the center, is a 'drive line' and just means the horizontal drive needs adjustment. Maybe you can have the same thing in the vertical? Check the output stage and any resistors there (IIRC, the vertical section uses resistors for dampers)

zeno · #24 10-24-2019, 09:10 AM

If the white line goes side to side it may be vert fold over. Check the
resistors around the height & lin controls especially high ohms ones.
Also the 'lytic at the cathode of the output. That causes lin problems &
is common in most tube sets. Its usually in one of the cans.
Last thing is the vert integrator that 3 legged thing.

73 Zeno

LFOD !

joe111671 · #25 10-24-2019, 02:42 PM

Quote:

Originally Posted by nasadowsk

Horizontal line, or vertical line? A vertical line, a bit to the right (or was it left?) of the center, is a 'drive line' and just means the horizontal drive needs adjustment. Maybe you can have the same thing in the vertical? Check the output stage and any resistors there (IIRC, the vertical section uses resistors for dampers)

Horizontal line. It actually did have a vertical white line on the right that would get wider as I turned the horiz hold control, but that went away after I got the picture adjusted. I'll go check the resistors later when I get home. Can they be tested in circuit?

Quote:

Originally Posted by zeno

If the white line goes side to side it may be vert fold over. Check the
resistors around the height & lin controls especially high ohms ones.
Also the 'lytic at the cathode of the output. That causes lin problems &
is common in most tube sets. Its usually in one of the cans.
Last thing is the vert integrator that 3 legged thing.

73 Zeno

LFOD !

All the lytics & paper caps are replaced with new. For the ones where the exact value wasn't available, I used the closest I could, and I believe all were within 10% of the original value. I remember seeing a youtube video by shango066 where he built a new integrator for an old Zenith. I'll have to go find it if all the resistors are ok.

Electronic M · #26 10-24-2019, 03:19 PM

Quote:

Originally Posted by joe111671

Horizontal line. It actually did have a vertical white line on the right that would get wider as I turned the horiz hold control, but that went away after I got the picture adjusted. I'll go check the resistors later when I get home. Can they be tested in circuit?

All the lytics & paper caps are replaced with new. For the ones where the exact value wasn't available, I used the closest I could, and I believe all were within 10% of the original value. I remember seeing a youtube video by shango066 where he built a new integrator for an old Zenith. I'll have to go find it if all the resistors are ok.

If the line is horizontal it is probably not related to the horizontal stage and most likely a symptom of a vertical stage issue.... since all your caps are new check the resistors and tube in the vertical stage.

joe111671 · #27 11-10-2019, 08:49 AM

I tested all the resistors in the vertical section and they were mostly high but within tolerance, other than a handful that read way low, I would have to snip them out of the circuit to test so I left them. I guess that leaves the tube & integrator, but I've put a good 50 hours on it and no change in performance so I put it back together and I'm enjoying it. Next I'm going to recap the other console that I'm not keeping and will update when I'm done.

joe111671 · #28 02-08-2020, 06:09 PM

Update on this thread, I replaced the vertical output tube on the set and it took care of that horizontal line and the vert. linearity issue, and it has full vertical right away now, no extra warm up needed. I've put dozens of hours on it and it's solid.

The other set with the cataract is put away for now. I'll recap it at some point, but I had to get it out of the way for the holidays, so I put the chassis back in and hauled it upstairs where it's waiting patiently.