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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Aug Sat 20, 2016 6:43 pm 
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Location: Riverside, CA
Don Cavey wrote:
That chassis seemed to have only a few rust spots, not major damage like some that have shown up here.

Under the chassis there are only a few rust spots. I'll probably just touch those up with Naval Jelly and then, as you recommended, touch up with paint on a Q-tip. But the top of the chassis has a fair amount of light rust. It's just hard to see in the photo above because the chassis is covered in years of dust.

Don Cavey wrote:
Also, as for that "Candohm" metal resistor that is mounted to the chassis R-62, you could get a good metal wire-wound replacement for it and attach it to the chassis (for heat sink purposes). They are notorious for the paper inside going bad and the wire inside shorting to the metal case.

R62 is supposed to be 3500 ohms and, according to the Zenith service literature, +/- 10%. Mine measured 3580 ohms, exactly 10% over, so out it goes. Couldn't find a replacement at Digi-Key but found one at Mouser (P/N 71-RH5-3.5K). I was hoping to find everything at Digi-Key to save on shipping.


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Aug Tue 23, 2016 6:02 am 
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Parts are on order for the power supply. Just spending time removing rust with Naval Jelly. Will post photos when I'm done.


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Mon 19, 2016 1:30 am 
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Been awhile since I've worked on this. The power supply has now been completely overhauled. I cleaned up the major rust spots and cleaned off the grime from the external wires. All caps and resistors have been replaced. Here is a BEFORE:

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AFTER

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The #6 tube lug on the 6BF5 broke right off when I tried to desolder the connections. I had to get a replacement tube socket off of eBay.

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The next step is to remove the chassis from the cabinet. But first I need to clear some room on my bench. I'll probably get to it later this week.

- Geoff


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 7:18 am 
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I removed the chassis from the cabinet tonight. It is very dusty and dirty. You can see that the plastic bezel around the CRT has cracked. I'll probably try and repair this with some JB Weld.

Here is a high resolution scan of the service information (600 dpi, 54MB):

https://drive.google.com/file/d/0BzQx4c ... sp=sharing

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Here are some photos of the chassis:

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I'm a little concerned about what looks like rubber around the yoke. It is dry and is crumbling away:

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Can anyone recommend what to use as a replacement?


Here are some photos of the inside of the yoke. Is there any good way to clean this or should I leave it as is?

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Now my biggest concern... the horizontal output transformer. It looks like all the black coating has melted off. Here are some photos before I dusted it off:

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After dusting lightly with a small painters brush:

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Also, it looks like there may be a wire sticking out. Upon closer inspection of the photos though it looks like some sort of wax that got melted and pulled away.

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I have an Eico 944 Flyback Checker that I rebuilt some time ago. I refurbished it in preparation for this set. I'll have to get it out and figure out how to use it.

- Geoff


Last edited by Geoff on Dec Tue 20, 2016 3:03 pm, edited 1 time in total.

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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 10:34 am 
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Geoff,

For the broken off lug for the tube socket, are you going to try to extract the broken piece? I have had success with just replacing the one lug and not the whole socket.

Just a thought...

_________________
Don


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 3:00 pm 
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I already replaced the entire socket.


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 5:25 pm 
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Geoff wrote:
I already replaced the entire socket.


Good enough. Glad you got it taken care of.

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Don


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 6:25 pm 
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I have Thursday and Friday off so I'm going to test horizontal output transformer with my Eico 944 flyback tester on one of those days.

Can someone please give me feedback on how the horizontal output transformer looks? If it tests good, am I going to have to recoat it? What do people use to recoat these?

Thanks,
Geoff


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 6:43 pm 
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Looks OK to me other than that bit sticking out. If it's a wire that could be bad. I've used corona dope, and acid free silicone to recoat flybacks. Both work well but be very careful not to damage the fine wires. Looks like your yoke cover is made from the type of plastic that deteriorates over time. Common problem.

I've had good luck fabricating new ones from sheet styrene cut to shape and glued.

Some photos here: https://www.flickr.com/photos/70039806@ ... 009940550/


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 7:45 pm 
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Yes, if it is a wire I'm not sure what to do. I just lightly dusted everything off and took some photos. It was getting late last night and I did not look at it any further. I'm hoping it is just a piece of melted wax or something hanging down.

When you recoat the flyback do you leave the original, crumbled coating in place and spread the coating over it or do you try and remove the original coating as best as possible? I would think the former since it may be risky trying to remove the original coating.

Great photos on fabricating your own yoke cover! Looks like I may have to do that, but I'm going to take this very slowly. One step at a time.

BTW, I love the videos you post on YouTube. Watching those has given me the confidence to move from radios to my first TV.

Thanks,
Geoff


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 8:13 pm 
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In the Eico 944 manual it says you need to set the calibration point to either Iron Core or Air Core, depending upon the type of flyback and yoke you are testing. Can someone tell me how to determine if I have an Iron Core or Air core flyback and yoke?

Thanks!


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 8:28 pm 
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Thanks I carefully remove as much of the old coating as possible. You have an iron core flyback and yoke.


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 9:13 pm 
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Location: Madison, WI
Hi Geoff,

I restored the same chassis about four years ago, and my flyback looked just like yours does, including the loose wire. I found the wire after I was trying to remove as much of the coating as I could. I feared the worse, and was sure I had ruined the fly. Well, I tried the set and it worked fine with the wire just hanging there. I asked for opinions, and it was suggested that it may be for a secondary tap that was not needed for this particular FBT. Anyway, I recoated the tire with sensor safe RTV and it's been working fine ever since.

There are photos of all this in a thread that I made either here on ARF or over on Videokarma, but I can't seem to locate it right now :oops:

Good luck,

Clark


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 9:22 pm 
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bandersen wrote:
Thanks I carefully remove as much of the old coating as possible. You have an iron core flyback and yoke.

Thanks!


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 9:58 pm 
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Clark, K9OA wrote:
I asked for opinions, and it was suggested that it may be for a secondary tap that was not needed for this particular FBT.

Might be. Here is the parts list from the Sam's folder.

Image


And I'm hoping someone can help a new guy to TV's out. I'm going to need help to understand how to use my Eico 944.

Zenith schematic only is here:

https://drive.google.com/file/d/0BzQx4c ... sp=sharing

The 944 instructions are below.

Step 2: It says to remove the plate caps on the High Voltage Rectifier and Horizontal Output tubes. Does that mean to revove the connection from the top of each tube (in this case V18, V19 and V21)?

I am at work and cannot look at the set but Step 4 says to unplug the deflection yoke assembly. I'm assuming there is a plug somewhere and no desoldering needed?

Step 5: Unsolder one side of the width coil. That's L24 where it connects to C83.

Step 8: Connect the leads across each winding of the transformer. For the first winding on the schematic that would be the top (plate) of V21 which was disconnected in a previous step and C83. For the scond winding that would be C79 to the bottom of C82 (assuming it is not shorted)???

Do I need to worry about testing at the taps? Do I need to test the L24 winding?

Step 9: Connect the two test leads to the two plate cap terminals coming from the transformer. Where is this on the schematic?

I'll follow up in a later post with questions about how to test the yoke.

Image
Image

- Geoff


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Tue 20, 2016 11:39 pm 
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I have that exact EICO Flyback/Yoke tester and have used it, but I never liked it (I've read its best to let the tube warm up for a 1/2 hour prior to using it). My ohm meter worked better for me using the ohm ratings from Sams. But that's just my preference.

I had a similar plastic bezel breakdown on one of my Zenith portholes. What I did was affix aluminum foil around the crt front and put the bezel on the crt the best you can by taping it with duct tape to the crt. I than applied fiber glasses mesh/resin to the top portion with ample mesh overhang to later fold underneath. Once the glass cured I removed the bezel and subsequently glassed the underneath and applied additional mesh around the corners being careful to shape it exactly as the original. Its pretty easy to do and strong as well as flexible.


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Wed 21, 2016 12:15 am 
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An ohmmeter won't necessarily detect shorts in the windings. Yes, remove the caps from V18, 19 and 21. I do not know if there is a plug for the yoke in this model. Yokes are often hard wired and you'll need to do some unsoldering to test it. On the positive side they are usually fine - don't think I've ever encountered a bad one.

If you're going to go to the trouble of testing it, you might as well test every tap. The two plate caps in the test procedure are the ones on V18-19 (shorted together) and V-21.


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Wed 21, 2016 4:44 am 
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bandersen wrote:
An ohmmeter won't necessarily detect shorts in the windings. Yes, remove the caps from V18, 19 and 21. I do not know if there is a plug for the yoke in this model. Yokes are often hard wired and you'll need to do some unsoldering to test it. On the positive side they are usually fine - don't think I've ever encountered a bad one.

If you're going to go to the trouble of testing it, you might as well test every tap. The two plate caps in the test procedure are the ones on V18-19 (shorted together) and V-21.

Thanks. I'll post a follow-up on either Thursday or Friday.

- Geoff


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Wed 21, 2016 9:17 pm 
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I found the thread about my flyback here on ARF:

http://www.antiqueradios.com/forums/viewtopic.php?f=3&t=221385&p=1853707#p1853707

As Tom Schulz commented in my thread, it's too bad I didn't measure the resistance between the hanging wire and the terminals of the secondary before I re-coated it. Might have been able to confirm that it was indeed an unused tap.

-Clark


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 Post subject: Re: My Next Project - 1951 Zenith H2445R Tennyson Porthole
PostPosted: Dec Wed 21, 2016 10:44 pm 
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Clark, K9OA wrote:
As Tom Schulz commented in my thread, it's too bad I didn't measure the resistance between the hanging wire and the terminals of the secondary before I re-coated it. Might have been able to confirm that it was indeed an unused tap.

-Clark

Thanks Clark. I'm a little wary about even touching that wire. It seems to have a coating on it and I'm afraid to pull on it and cause any damage. I'll look at it again when I break out my Eico 944 tomorrow or Friday.

Thanks again!


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