Motorola 12K2 restoration
 

I'm finally getting around to the bug eaten set I picked up in Cincinnati over a year ago.

It's a Motorola 12K2 with a TS-53 chassis and 12LP4 CRT.

Some trim is missing and wood bores have been at it, but otherwise the cabinet and chassis are intact.

The CRT is a little weak, but I think it will produce a watchable image.

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I have some nice mahogany veneer I can use to reproduce some of that trim.
The veneer is a bit beat up, but I think I can salvage it.
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We had that model at the TV shop where I worked until the early 80s. It worked. I would fire it up every now and then and it would get the looks by the passers by. I almost screamed like a little girl when I saw it missing when I stoped by in mid 80s. The owner sold it to the Burt Reynolds theater as a prop! I had an RCA 1948 in a metal cabinet but this was just an awesome looking piece in its wood cabinet.

Something seems missing, like the HV section. And that power transformer looks awful small!

Nothing missing. That's only a filament transformer; there are seleniums underneath in a voltage doubler arrangement. The Flyback and 1B3 are also mounted underneath. Motorola made many variations of this chassis.

That's what I thought before I saw the service info. The flyback and HV rectifier are hiding under the chassis.

The power transformer is just for some of the tube filaments. There's another transformer below for a few more tubes including the CRT.
The B+ comes from rectifying and doubling the AC line. So, it's a hybrid hot chassis, transformer set!

(Doh! David beat me to it :))

Grrr - broken capacitor wafer mount.
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The yoke is a replacement. I tested it and the flyback using an Eico 944. Both passed although the flyback gave a high pitched squeal.
http://farm3.static.flickr.com/2098/...fac400c6_b.jpg

DO IT RIGHT! I've seen this on a couple other late 40s Motorola chassis, but not on earlier ones.
Maybe they were making too many mistakes on the line ?
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Here's the only odd thing I've found so far. It's three 1K resistors in series connected between the focus rheostat wiper and ground.

I don't see it on the schematic or other photos I've seen of this chassis :scratch2:

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Well Bob, glad to see that you are off to another adventure! The progress should be fun to watch and I look forward to it.

:D Rather lame management if they thought that placing such stickers on the chassis would make the difference. :scratch2:

IBM had "Think" signs in their offices; a friend of mine has one from the 1930's that he used to keep in his office (at IBM). I wonder how well those worked?

well enough that their laptop lines were "think"pads

Hi Guys ,

Ill bet your absolutly right , , the "Do It Right" stickers were probablly the 1940s version of "The Team Concept" and other vapid management slogans that are supposed to get us worker bees in line . Didnt work then , dont work now , and a typical example of corporate waste . If these companies want good , happy workers who take pride in their work there is only one sure way to accheive that ...... Pay them a fair wage and make them feel like they ARE actually a valued asset to the organization . Everything else is just smoke .


Anyway , Im watching your Motorola restoration thread with intrest , , , , I may just have to go out and find some nice old TV to restore here myself ( Ive already done a 1950s Olympic , I just dont know how to post photos here yet) .

Oh yea , also , , , Ive reported "rootasoo" s post (the one that Is , or was , above mine) as spam :nono:

that looks a lot like the motorola I have, have fun with that cluster of caps at about 8:00 for do it right, must be 10 tied to one term strip lug.

Looks like it should be a nice "fix-up" and we will be watching.

O.T. We should be the brains behind these lame campaigns that they sell to corporations. The Bell System went through that stuff in the 80s and by 5 years later, all of the stuff that they crammed down our throats was out the door and laughed at (as we did behind their backs ;)). Large corporations seem to think that they can solve any problem with another pile of Bovine Scat slung at the workers. They always seem to think that they are superior and smarter than their worker bees. (rant off)

Bell System huh? I worked for them too.
Remember the campaign PPP - Pride in Personal Performance?

We jokingly had other words for PPP :-)

Carl

I started on that cluster last night. Fun is right :drool: I've found evidence of a few crude repairs including some 6AG5s in 6AU6 sockets.

I wonder if the "Do it right" stickers were placed on the chassis after it failed a test and was sent back for rework?

One might imagine that all those numbers scrawled in crayon might be wiring steps which were found to be incorrect upon inspection.

It would be fascinating to learn more about how the assembly line really worked. At one time, there must have been hundreds of thousands of people in the U.S. working in point-to-point wiring of radios and TVs. I've seen only a few things here and there documenting how these lines really ran and exactly what a typical worker's job was like.

that set did have a odd PS, there was a filament trans for everything but the damper, then an odd ball looking trans for the damper and of course the doubler for B+, not isolated. FYI, I watch that set a lot and it still has the Se stacks in there (I did NOT replace them with diodes, so far so good). I know I will prob get some comments about the forthcoming failure and stink of them when that happens. I seem to recall having some intermittant audio, think that was a defective 6AL5 in the FM ratio detector (may have been a tube socket on that, just cant recall right now).

on company signs, we had a lot of "safety first" of course if you saw the walls around the fork lift you would know why, I think there was a hole punchedin by the forklift right thru the poster, it was just asking for it....

HR loved signs, I think a lot were mandated by the feds...

I found another "Do It Right" sticker under the channel selector in my 9T1.
http://farm4.static.flickr.com/3268/...db46ed4ef7.jpg


There's also an autoformer tap for the 25L6 and a separate secondary for the CRT and one of the 6AU6s.
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Speaking of the 6AL5 tube - I broke a leg off it's socket :tears: For now, I just soldered it back right to the tube pin. i guess I'll have to drill out the rivets and replace the socket.
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I've started working on the cabinet. First, I removed the screen bezel and speaker.
The green foam was stubborn in a few spots, but I got it off eventually with the help or a razor blade.

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The feet had seen better days so I glued and clamped them.
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Now how to deal with those bug holes ?
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I did some experimenting with products available locally and settled on this Elmers wood filler. This cabinet is brown mahogany and the Elmers mahogany was a bit too red. I found that a blend of 2 parts mahogany, 1 part walnut looked OK once stained.

I did a little stripping test before filling in the holes and discovered the stipper sludge not only gets in the holes but discolors them too. So I'm filling them in first.

After filling in the holes, I've been scrapping off the excess with a single edge razor blade. A lot of the finish is coming off in the process so I think I won't need much stripper after all.

After staining and grain filling, I might also use some Mohawk brown Mahogany toner I have on hand. Toner lacquer works pretty well for hiding repairs.

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Mahogany gel stain test with several blends of wood filler.
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It's about as much fun as it looks :drool:
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Looks like you've got most of that fancy cabinet trim work but even if not you could trace the pattern onto some veneer of the same type and cut it out with an exacto knife.

Reminds me of the balsa wood airplanes I use to make as a kid. I had to cut out each piece from a flat sheet of balsa wood, took weeks to make one.

The numbers written in crayon on the chassis bottom look like inspectors numbers. Each chassis inspected by an inspector as it passed through a section of the line. Looks like it went through at least six stages of inspections. The initials are possibly from the the guy or girl that signed off on the whole chassis. Just a guess.

As for the metal trim, it's gone into the electrolysis vat to remove the rust.

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Once that's done, I'm going to try these products.
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LOL - I made models like that too.
I'm missing about 1/3 of the trim. I have some veneer left over from another project and I'll cut it out just like you described.

Interesting looking tub of goop you got there. What's that all about?

Re: the three 1K resistors in series. Don't know if it's true in this case, but sometimes TV mfrs. used several resistors in series that added up to the value required where there was a high potential. Several resistors gave a long leakage path compared to one resistor that could arc over.

better heat disapation too.

Gota know what's in that tub of goop??

Aha. I was wondering why my DuMont RA-113 uses a chain of three 470K resistors in the HV tripler circuit.

Phil Nelson

P.S. To learn about the goop, search for "electrolysis" in this forum.

http://antiqueradio.org/art/DuMontRA...ChainParts.jpg

I posted some details of the process in this thread.

http://www.videokarma.org/showthread...=250143&page=4

Pretty amazing results. I'm sure I'll try that in the near future. Thanks

I've seen that in the Motorola electrostatic sets for the HV divider. It seems to be a crude repair in this case. There should be a 3.3K resistor in the focus circuit elsewhere. That had been replaced with a 3K resistor and these 3 1Kadded as well for a total of four resistors. I just removed them all and put in a single 3.3 K.

I found scraping to be an effective way to remove most of the finish. Certainly less messy than the areas where I resorted to citrus stripper.

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The top had a few chips in the veneer. I cleaned up the edges and carefully cut patches from some salvaged veneer. After gluing them in, a little trimming and sanding made them almost disappear.
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BTW I took the first two pics with natural daylight and the last at night with CFL lighting and a flash. It makes quite a difference !

I like the Chinese frieze pattern running aroung the top of the TV cabinet. Looks very similar to an Edison C-250 phonograph. The Edison is mahogany too.

Neat. The GE 802 has it as well, but just in the front.

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I thought that that was Greek or Egyptian style, but I'm not up on my interior decorating... :D

Here's the original ad in a brochure I picked up recently. Click to see the full sized scan.

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Looking Good I think you will get a nice finish on that set. Use a couple of spray cans of semi gloss poly for the finish and take your time.
You did an amazing job on the veneer replacement. It took me a minute or two of looking at the pics to even begin to see even the slightest sign
of the repair. How did you get the cut line to match the new piece and how did you get the cut line to disappear after you put in the new piece?

Thanks. I'll be using Deft gloss lacquer and rubbing itout with pumice and rottenstone. It has nitro-cellulose in it and produces a really nice finish. It's also what they used originally.

I was lucky in that I had some vintage mahogany veneer scraps salvaged during another project. The color and grain was a very good match. I matched the angles by holding a strip of the patch veneer next to the missing part and lined up a utility knife to score a line. When I cut out the patch, I also under cut it so the top surface overhung. That allowed me to get a very tight seam against the old veneer. I also rubbed a little sawdust into the glue to fill in any voids.

I'm in the home stretch (I hope). All that's left before a power up attempt are the two multi-section electrolytics.
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I colored the wires with markers to aid in reconnecting them. I also found one that had broken loose long ago. Maybe that led to the sets retirement :scratch2:
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One down, one to go. I used Nichicons rated for 105C.
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I also finished the lower trim.
Here it is before and after rust removal. It's quite deeply pitted in areas.

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Several rounds with first rusty metal primer then filler primer and sanding filled in the voids and should prevent the rust returning.
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Finally time for the gold lacquer.
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Here's a preview against the old grille cloth. Looks pretty good I think.
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Reminds me of that TV show "Rust to Riches"

I still say the Smithsonian is missing out on one heck of a restorer/curator.....another awesome job as usual.

Cheers,