1949 Zenith Porthole Restoration

[Paul Knaack]

Originally Posted by Eric H

Are you testing it in circuit? I'm pretty sure it has to be completely disconnected.

It doesn't look all that bad, I wouldn't give up on it until you get the set fired up and see if it works. Mine actually shot sparks out of it so I was pretty sure it was shot.

I also didn't have high voltage on first power up on mine. Turned out it was missing the phonevision jumper plug on the back of the chassis. It took me at least an hour of curcuit tracing to figure that out.
I'll dig through my stuff and see if I have any more maroon knobs for it.

[Radiotronman]

You know, I never looked at that. I'll definitely see if it's that, I know what you're talking about.


Thanks,
Scott

[Radiotronman]

I looked at the chassis tonight and it does have the phonevision plug in its correct socket at the back. Back to the drawing board. A friend of mine may have a replacement flyback for me. I'll recoat the picture tube once I see some progress. It's a 12lp4 and tests ok.

Scott

[Electronic M]

I've seen worse looking flys work, and nicer ones dead, and I've had my EICO fly tester lie to me occasionally....Case in point don't judge a book by it's cover. Get the H osc thru HV sections recapped and the osc. tuned, then you'll have grounds to declare it dead with certainty.

[Tim]

Originally Posted by Radiotronman

Eric,

That is an interesting idea! Now I've got to find a fly-1, because I don't have one. That will hopefully be easier to find.

This looks like one but condition unknown. No affiliation.

http://www.ebay.com/itm/121650338736...%3AMEBIDX%3AIT

[Eric H]

That looks like one but there are a lot of them that look the same. If anyone has a 49 Magnavox Sams they could check and see what fly it used that should tell.
If it uses the same sweep tubes and yoke it'll probably work.

There were a lot of sets from 46-49 that used the Fly 1.

[Radiotronman]

A friend of mine gave me a few flybacks that are listed as suitable replacements for my set. One being a fly-53. I will recap the horizontal section as suggested first, to see if any life is shown left from my original flyback. If still nothing, then I'll try replacing with one of these three.

[Radiotronman]

Getting ready to recap the horizontal section and I notice that the Sams listed for this model doesn't even match. I can replace what I see in the set, but how do I know what the sand coated resistors are when the sand has fallen off with the markings?

[Paul Knaack]

Try this schematic, Rider 3 page 13-14. Wide band if revised chassis
http://www.earlytelevision.org/pdf/z...f20-rider3.pdf
This one matched my chassis.

[Radiotronman]

Thanks for the help. I forgot I actually had a partial set of Rider's book, including that volume. I'll study it and see if it matches my set.

[Radiotronman]

Ok,

So I'm beginning recapping and resistor checks on this set. Many sand coated resistors, luckily most still have part numbers on them so I can reference what it is on the schematic. There's one that is missing all of its coating. That should be fun tracing that part back. I'm going to replace as much as I can, with what I have on hand, then order the rest. Three electrolytic cans are hidden on top of the chassis, underneath the yoke assembly. So I had to remove them to access these cans.

[Radiotronman]

This is the resistor in question, missing all of its sand coating. Another was like it, but still had the side with part number on it. That one was completely open. Yes I can trace them back on the schemstic, but it's a heck of a lot faster if I can look it up under the resistor part values on the schematic.

[Radiotronman]

Ok,

I've replaced the few caps that I had left over from a prior set I restored. I placed an order for the remaining caps and some open power resistors that were sand coated. I also ordered the 20 watt power resistor that was completly open off of ebay by Clarostat. Now I sit and wait for the parts to arrive.

[Radiotronman]

Parts came today, time to get busy!!

[Radiotronman]

Cap replacement is coming along. I also replaced two of the sand coated power resistors. I'll finish them and replace the three electrolytic cans under the yoke assembly.