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 Post subject: Zenith H2447R 19" Porthole TV
PostPosted: Oct Mon 23, 2017 2:27 am 
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Just got this this weekend.

I tested the 19AP4 CRT and after cooking it awhile and doing a Clean on it using my BK 467 CRT tester, the CRT did come to life but just in the green. This picture shows the condition with 6.3V filament.

Do you think I need another CRT? Let me know.


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File comment: This is with 7V for the filament.
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File comment: This is with a 6.3V filament.
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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Oct Mon 23, 2017 3:13 am 
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That should be fine. I have seen plenty of older black and white CRT's that show a very watchable picture in the 100 to 200 microamp range, which is well down in the red area on a tester. Yours is quite a bit higher than that. Only way to find out for sure is see how it looks when the set is working properly. Worst case, you put a brightener on it while you look for a better one, but I think that will give a decent picture in a dimly lit room.

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Oct Mon 23, 2017 3:16 am 
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I agree with Mr. Detrola, give it a try.

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Oct Tue 24, 2017 12:47 am 
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That is a nice-looking set. It's a model that accommodated the Zenith "Lazy Bones" remote control. That big shaft coming out of the back of that huge turret tuner took a drive chain or gear (I forget which) to the channel-change motor. The stylish little hand control at the end of 17-foot cable allowed you to move the channels up or down. Nothing more than that, though!

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Oct Wed 25, 2017 1:02 am 
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A couple of my Zenith porthole CRTs (metal type like yours) tested bad/weak, (1 bad 1 Weak) and they illuminated just fine and keep on going with good contrast and brightness.


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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Fri 03, 2017 3:52 am 
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Location: Waxahachie Texas
OK, here goes. I've started on the restoration of this TV. In the next few days or week I'll get caught up with the progress that I've made.

First off I'm working on the HV cage and Fly back. The FB coating was pretty melted and cracked. What I did to restore the FB will be part of the upcoming posts. What I'd like to show you guys and get opinions on is that the 1B3GT filament winding that is around the core of the FB might have an issue. The wire is held off the FB core with 2 thin pieces of a fiberglass like material. Where the filament winding has passed through those pieces, it looks like they "dug" into the insulation, thus compromising the insulation. Here are 2 pictures of the filament winding and how it is held in place around the FB.

Now here is a close up of the damage to the insulation. It goes in some but not all the way to the conductor.

I think I need to replace that wire. Now here is another question. If the original wire is lets say 20Kv and I use 40Kv wire, will there be enough "juice" to get through the "extra" insulation of the 30Kv wire to work the 1B3GT?


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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Fri 03, 2017 1:55 pm 
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I think the important thing to consider is the proximity of the wire to the flyback. If it is the same distance as the original wire, I would thing that the voltage induced into the wire would be the same. But I am a hobbyist, not technician. Wait for others to chime in here...

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Fri 03, 2017 1:56 pm 
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How about a piece of wire salvaged from a CRT type computer monitor? They should be plentiful.

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Fri 03, 2017 4:17 pm 
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I don't think there would be any problem with replacing that filament wire with one with one with increased voltage ratings.

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Fri 03, 2017 4:58 pm 
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Thanks guys for the comments. I have some 40Kv wire from an old TV that I'll use that is the same awg.

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Sat 04, 2017 6:02 pm 
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Let's try and get caught up a little at least from the start.

After removing the chassis from the cabinet, I took many of the customary initial pictures of both the main and power supply chassis. I removed the tubes earlier when transporting the TV back home. I then removed the CRT.

I then decided that this thing needs a bath. I went to the local "Quarter" car wash. Yup the local car wash. I used the "Presoak" setting to spray off both chassis on top and on the bottom. Then I used the "Ionised Water" to rinse them off. These settings at the car wash use a lot less pressure and with the wand 3 feet away, the car washing did an amazing good job of cleaning those chassis. Once back home I blew off the excess water with my blow gun set at 40 pounds. Then the chassis went into the oven set at 170 degrees F for several hours. Well worth the effort.


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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Sat 04, 2017 6:07 pm 
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I then wanted to check the "health" of the chassis by checking all the transformers and coils. All checked good even the nasty looking flyback except the H Hold coil L22 (Sams).

I removed the coil.

I then unwrapped the black tape. Sure enough there was a broken wire.

I was an easy repair to make. I unwound 1 turn and cleaned off the insulation and soldered it back on to the green terminal. If you look closely you can see the original wire underneath the white tape.

I then used some black electrical tape to secure the wire.


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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Sat 04, 2017 6:08 pm 
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Then I labeled each component according to Sams 120-13. This is my usual practice. This helps me understand the chassis and the parts locations. When labeling the parts I checked their value against the parts lists. This readily points out what the differences are. Sure enough there were just a few. The Sams had a few typo errors and I also used Riders V6-1 to cross check both the Sams and Riders and the chassis. The biggest difference was R39 (located under L14) is listed as a 33K resistor wired to the 130V bus. This was what the picture shows to be in the Sams. But the chassis has a 75K resistor wired to the 360V bus. The Riders shows a 68K wired to the 360V bus. I'm thinking that perhaps a 68K 1W resistor was in short supply and a 75K was used on the assembly line. Most likely I'll use a 68K resistor.

Also you'll see that I removed several shafts from the front of the chassis to a pot and the tuner to have better access to the components. These will be cleaned before reinstallation.


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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Sat 04, 2017 6:18 pm 
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I removed the HV cage and disconnected the 4 wires going to the flyback.

After removing the 1B3GT plate wire along with the 6BQ6GT plate wires and the door knob cap and 1B3GT socket I ohmed out the coils. They checked good. I then cleaned up the coils by removing the melted covering by chipping it off and using heat to melt it some. I used a lot of Q-Tips and acetone. I then cleaned off the yellowed cad plating and cleaned up the rest of the assembly.

After cleaning I then baked the assembly at 225 degrees F for several hours. I then used my MG chemical Super Corona Dope and brushed on 4 coats. 1 coat on one side then bake for an hour, the do the other side and bake it again for an hour. This was repeated for 4 coats. The coils are just about filled and 2 or 3 more coats I'll be done. Stay tuned for the results.


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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Sat 04, 2017 7:54 pm 
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Here are the Hi-Res docs for this project.
Once the click opens up the file, click on the "Open" tab in the upper right. Click on Adobe Acrobat Reader and then when it opens up you then can save it as like any pdf. Note: very large files.

Schematic:
https://www.dropbox.com/s/imuvrxrdk4bgo ... c.pdf?dl=0

Resistor, Inductor, and Capacitor Location"
https://www.dropbox.com/s/e977okir2elrt ... n.pdf?dl=0

Sams 120-13
https://www.dropbox.com/s/xwcrok7re104d ... 3.pdf?dl=0

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Sat 04, 2017 9:04 pm 
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Were there any paper tags on it before you washed it?
I noticed you've got a great collection of test equipment there.

One caution about home kitchen convection ovens, the thermostats aren't very accurate and the temperature tends to "hunt". That means the temperature on small parts of low mass can get too hot briefly. Obviously you have things well in hand with yours.

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Sat 04, 2017 10:54 pm 
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Joined: Jan Sun 18, 2015 5:01 am
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Location: Waxahachie Texas
Notimetolooz wrote:
Were there any paper tags on it before you washed it?
I noticed you've got a great collection of test equipment there.

One caution about home kitchen convection ovens, the thermostats aren't very accurate and the temperature tends to "hunt". That means the temperature on small parts of low mass can get too hot briefly. Obviously you have things well in hand with yours.


Good question on the tags. Yes, there were but I covered them up with wax paper and clear packing tape before the wash. I forgot to mention that.

Yeah, ya gotta have 2 or 3 of each right? :D

The chassis was put on the highest shelf possible in the oven because the heating element is on the bottom. 170 degrees was used because that's the lowest temp the oven could be set to.

As a matter of fact, every few minutes I would turn off the oven, and then every 10 minutes I would turn it back on and so forth. It kept the chassis pretty warm but not warm enough to melt the wax off of the components.

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Sun 05, 2017 1:40 am 
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When I was a lad, my younger brother had a plastic model that he had painted. For some reason the paint wasn't drying like it should. I had the idea of putting the oven on its lowest setting to dry the paint. It didn't melt the plastic but when we opened the oven it looked like a caricature of an airplane. Must of stress relieved the plastic. I don't think he ever forgave me for my bright idea.
Much more recently, out of curiosity I put a fine thermocouple in my oven. I don't remember exactly but the temperature variation was huge as the heating element went on and off, maybe a 50 degree swing! That would of been the air temperature, a solid object would have smoothed out the swing some.

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Sun 05, 2017 5:20 pm 
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Nice project. A

I know I will learn a few things from your project here.

I wanted to warn you about the fine tuning shaft inside the tuner. They are prone to break easily. Every time I tried to restring one it snapped in half at the pulley. No-matter how careful and gentle I was, they all snapped. Its made of some odd material that seems to weaken with the passage of time.

I've fabricated a few replacement shafts using a wood dowel as the shaft material and never had a problem with any of them. I also try to use a belt instead of restring if I have one in my stash.

It looks like yours does not require restringing. But just in-case, be aware.

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 Post subject: Re: Zenith H2447R 19" Porthole TV
PostPosted: Nov Sun 05, 2017 5:44 pm 
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Location: Waxahachie Texas
clsoca wrote:
Nice project. A

I know I will learn a few things from your project here.

I wanted to warn you about the fine tuning shaft inside the tuner. They are prone to break easily. Every time I tried to restring one it snapped in half at the pulley. No-matter how careful and gentle I was, they all snapped. Its made of some odd material that seems to weaken with the passage of time.

I've fabricated a few replacement shafts using a wood dowel as the shaft material and never had a problem with any of them. I also try to use a belt instead of restring if I have one in my stash.

It looks like yours does not require restringing. But just in-case, be aware.

Attachment:
23G24 Wood Shaft.jpg


Thanks for the information. However mine has already snapped at the pivot point. :(
I'll be doing a post on the repair later.
The original material is Phenolic.

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