Zenith A1512J restoration
 

A friend has four or five of these "bug eye" sets and has been very anxious for me to restore them. So much so, he went ahead and pulled the chassis and dropped them off at my doorstep. That's why you'll only see a chassis in the next few pictures. I don't have the CRT or speaker either, but I think I can rig something up.

A couple days ago I decided to tackle one while I wait some parts for my Tandem set. It has a 15A25 chassis and I dug up a schematic in a Beitmans from 1958. Looks like a typical series strung set with a voltage double for B+.
http://farm9.staticflickr.com/8346/8...695e3893_c.jpg

They used little solder "cups" rather than terminal strips. That's a first for me, but I quickly got the hang of them and replaced the dozen or so paper caps.
http://farm9.staticflickr.com/8481/8...d2570e41_c.jpg

I pulled the selenium rectifiers out and mounted a terminal strip for new diodes and electrolytics.
http://farm9.staticflickr.com/8345/8...2750984e_c.jpg

There are seven controls mounted facing up which were all very hard to turn. Likely a results of dirt, grim and moisture working there way in. The contrast was so bad I had to resort to a little surgery to free it up.
http://farm9.staticflickr.com/8346/8...e464fb4d_c.jpg

Time for a power up :) The proper CRT is a 14XP4 with a 450mA filament. I'm temporarily using a 600mA test 8XP4.
http://farm9.staticflickr.com/8489/8...dff4df5b_c.jpg

That got me sound :music:, but no HV.
I powered down the set, did a little poking around and noticed the 17DQ6 HOT was really hot.

The components around the horizontal oscillator seem to be OK. Then, I checked the HOT circuit and found a 100 ohm resistor was measuring almost 200. I'll replace that and see if it makes a difference.

Does anyone have a copy of the Sams for a Zenith 15A25 chassis (388-4) ? The schematic I'm working with has limited voltage info. Thanks!

I had to laugh when you mentioned "solder cups"! This must be a first for you to tackle some Zeniths. While those terminal strips may have been handy on a production line they don't make component replacement all that easy when there's multiples of leads at any one point and nearby wiring. Sometimes I will resort to some "J" hooks to minimize any connection/part damage in those cases. Plus, why heat up a nice solder joint if you don't have to.

They are handy though for exposure to test points on both sides of the chassis!

Hello is that the set that has the big handle that folds out from the front so you can carry it??? I have one for sale at my shop that needs tlc pictures hopefully will be posted after turkey day...Timothy

I obtained a copy of the Sams service info and quickly tracked the problem down to a bad coarse horizontal hold control. I worked on it with some DeOxit and managed to get a small portion of the rotation to conduct.

That got the hor. oscillator running and I have HV. No vertical tough.
http://farm9.staticflickr.com/8070/8...a17b7a26_z.jpg

Not surprisingly the vertical hold control also appears to be shot except at one extreme.

Mounting all these controls so they face upwards seems to have been a really bad idea :no:
http://farm9.staticflickr.com/8490/8...97ac00af_z.jpg http://farm9.staticflickr.com/8337/8...e26c1bc6_z.jpg

After tweaking the AGC and fine tuning I finally got an image of sorts.
http://farm9.staticflickr.com/8340/8...ffbc1da5_z.jpg

Next up I'll work on those controls some more and try to dig up a 14XP4 CRT.

I popped open the hor. and vert. controls and confirmed my suspicions. They're a rotted out mess :( There's plenty of corrosion and the carbon tracks have fallen apart.

Time to go hunting through my junk boxes for replacements.

http://farm9.staticflickr.com/8480/8...05244970_b.jpg

I found a couple controls close to the right values and wired them in. That got me a stable raster but the cabinet won't fit unless I cut the shafts down.
http://farm9.staticflickr.com/8486/8...1e8aa55c_z.jpg http://farm9.staticflickr.com/8066/8...5be4e8ae_z.jpg

Does anyone know where I can get twist tab panel mount pots like this ? AES only has 250K and 500K, but I need 25K and 750K.

http://www.tubesandmore.com/products/R-V500K-N2
http://www.tubesandmore.com/sites/de.../r-v100k-n.png

Bob,

May be expensive but I would bet that Mark Oppat can make any type of pot that you need.

http://www.oldradioparts.net/

Tried Mark Oppat? http://www.oldradioparts.net/

He can probably make those from NOS parts.

[edit] oops, posted same time as kvflyer.

Thanks. I'll give Mark a try.

I finally got my hands on the rest of the set. The CRT turned out to be a headscratcher.

It's been rebuilt and the label indicated 14R/XP4. The 14RP4 is 600mA while the XP4 is 450mA so how could this CRT sub for both ?
http://farm9.staticflickr.com/8068/8...86a04488_c.jpg

I hooked it up to a CRT tester and it does draw 600mA which made me wonder how well it would work in this 450mA series set. Only one way to find out.

So it does work, but I have the brightness control nearly maxed out.
http://farm9.staticflickr.com/8490/8...ddcccc45_c.jpg

Now for a bigger issue. Serious lack of width. It's only about 50%. The schematic showing something called a "width sleeve" but gives no indication how to adjust it.
http://farm9.staticflickr.com/8203/8...535f273d_z.jpg

This is the first time I've encountered one of these. I assume it's this grounded ring around the neck :scratch2: Moving it around has little if any effect.

Any ideas ?
http://farm9.staticflickr.com/8341/8...113a85a9_c.jpg

I've seen some sets that have what looks like one layer of brass shim stock wrapped around the neck. Sliding that in or out of the yoke changes the width. I wonder if that ring originally kept such a sleeve from shifting location?

http://i452.photobucket.com/albums/q...ehn/sleeve.jpg

My Zenith T1816 bug eye also has a width adjustment sleeve. I was able to vary the width by a combination of rotation and sliding it in and out. But the range of adjustment was relatively small. I don't think that it would be enough to fill out the width in your case.

I just saw Kevin's post. And yes, mine has the wire ring (with a ground wire) over the brass sleeve to hold it in place.

-Clark

I found this old thread that discusses that (those, actually,) ring(s):

http://www.videokarma.org/archive/index.php/t-7467.html

I agree about the adjustment being minimal. I think I'd first take a look at the horizontal drive signal or horizontal output.

I experimented with a width sleeve when restoring my Capehart-Farnsworth 661-P. This article includes some explanatory paragraphs from an old TV service book:

http://www.antiqueradio.org/Capehart...Television.htm

The book says the ground connection is to prevent arcing from the sleeve to yoke windings.

In my casual experiments, pushing the sleeve in and out had quite an effect (granted, this was on a TV designed to use a width control, not a sleeve).

I don't see a sleeve in Bob's photo, only a ring. Is the sleeve pushed all the way into the yoke so that it's not visible?

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Bingo :thmbsp: I need to take the set apart again and dig it out :sigh:

I found it :)
http://farm9.staticflickr.com/8065/8...8f98bbe0_c.jpg

That's better :yes: Thanks for the quick help guys :D
http://farm9.staticflickr.com/8341/8...c4492ea7_c.jpg

It's hard to understand how a thin piece of non ferrous metal can affect the magnetic field enough to cause that much of a problem.

Yeah, that was pretty dramatic. That really shows how big of a problem a single turn short in the yoke would be. The service book Phil referenced said they came up with that idea in the late 50's, however my Setchell Carlson 25 chassis had a width sleeve as early as 1951. I wonder if Bart came up with that idea before its time. :D

I was quite surprised it had that much of an effect too. The height also increased about 20% with the sleeve slide back into it's original position.

When I experimented with a (copper) sleeve, it was able to block the sweep completely.

Phil Nelson

That reminds me of this neat YouTube video showing how a rare earth magnet reacts with different metals. http://www.youtube.com/watch?v=VEIYXomRdLY

Great video.

I would try soldering a control nut on the original pot mounting plate.
Then you can thread on the replacement pot. I've done it before.
Get out the old 200 watt American Beauty. :D

Why did you need to solder it to the plate ? I can just tighten it down with a wrench. The issue I have is that the pot shafts can only stick up about 3/8 of an inch from the mounting plate.

My AES pots arrived today. They're nearly identical to the originals except the shaft is too long.
http://farm9.staticflickr.com/8197/8...daacfe48_c.jpg

A Dremel tool and cutoff wheel took care of that.
http://farm9.staticflickr.com/8338/8...9b7de604_c.jpg

Much better :yes:
http://farm9.staticflickr.com/8208/8...6291b986_c.jpg

My reasoning was to solder the nut to the bottom of the original twist mounting plate. That was the intent, if the treaded bushing would protrude too far, so the shaft wouldn't be long enough to retain the knob.
Did you use the original carbon element from the old controls?

Got it. Thanks for the great tip :thmbsp:

The original carbon was trashed so I had to go with new controls.
http://farm9.staticflickr.com/8480/8...05244970_z.jpg

According to the former post, you said that AES didn't have the proper values. That's why I was inquiring about the pots. :scratch2:

Your set looks great. I love the bugeye sets.

Oh, that's right. AES only had some of the pots I need - 250K and 500K. I'll make do with what I have for the others.

I almost forgot to finish off this restoration thread!

Here it is post alignment and finally all back together. I should also mention that this is actually a model A1511G not A1512J.
http://farm9.staticflickr.com/8073/8...24491b41_c.jpg


http://farm9.staticflickr.com/8524/8...263d62f1_c.jpg

Very nice! :thmbsp: I've seen your Youboobtube videos also. Nice work and explanation for the uninformed. (I am informed but like to watch any way)

About Zenith I love their little capacitor look-alikes for the integrators and their blue turned brown defective disc caps. Horizontal and other tube sockets that break away from the chassis because of not enough solder on their solder cup/mounting pins. Don't even get me started on 4 legged capacitors!

Sorry about the pot rot I'll have to look for that. Thanks for the info

Soon I will be doing my '58 portable and 2 portholes as well.

PS (thanks again for the other thing).

Nice work Bob, as usual.:thmbsp: For me, those Zenith's have one of the best "'50's" looks of all the portables. The "rocket" side pods do it. A collector friend has a nice working blue/white one for sale and I'm so tempted! I just need a bigger apartment now!

Neodymium Magnets
 

That was great but it seems like he was just slowing it down at 1st by sliding it sideways at an angel... (it kinda just look like it was dragging) but then you could see it work much better later, when he compared it to aluminum/brass and then with copper. I found someone that may have experimented before Andy Davies did a year or so before that, check out Les's better experiment that he did with a copper tube! Magnets are amazing things, especially Neodymium types!

http://youtu.be/kCq1u_x07S8