Motorola 12K2 restoration - Page 2 - Videokarma.org TV - Video

Tom Albrecht · #16 05-19-2011, 12:15 PM

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.

DaveWM · #17 05-19-2011, 12:23 PM

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).

DaveWM · #18 05-19-2011, 12:28 PM

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...

bandersen · #19 05-19-2011, 05:34 PM

I found another "Do It Right" sticker under the channel selector in my 9T1.

Quote:

Originally Posted by DaveWM

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).

There's also an autoformer tap for the 25L6 and a separate secondary for the CRT and one of the 6AU6s.

Speaking of the 6AL5 tube - I broke a leg off it's socket

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.

bandersen · #20 05-21-2011, 12:22 AM

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.

The feet had seen better days so I glued and clamped them.

Now how to deal with those bug holes ?

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.

Mahogany gel stain test with several blends of wood filler.

It's about as much fun as it looks

charokeeroad · #21 05-21-2011, 12:30 AM

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.

bandersen · #22 05-21-2011, 12:41 AM

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

Once that's done, I'm going to try these products.

bandersen · #23 05-21-2011, 12:43 AM

Quote:

Originally Posted by charokeeroad

Looks like you've got most of that fancy cabinet trim work but even if not you could trace the pattern onto some vener 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.

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.

charokeeroad · #24 05-21-2011, 12:52 AM

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

Reece · #25 05-21-2011, 11:41 AM

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.

charokeeroad · #26 05-21-2011, 12:00 PM

Quote:

Originally Posted by Reece

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??

Phil Nelson · #27 05-21-2011, 01:01 PM

Quote:

Originally Posted by Reece

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.

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.

bandersen · #28 05-21-2011, 07:21 PM

Quote:

Originally Posted by charokeeroad

...

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

I posted some details of the process in this thread.

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

charokeeroad · #29 05-21-2011, 11:33 PM

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

bandersen · #30 05-22-2011, 12:10 AM

Quote:

Originally Posted by Reece

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.

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.