My Motorola VT-73 Arrived! - Videokarma.org TV - Video

leadlike · #1 10-02-2009, 02:35 AM

These have been on my tv watchlist for a while-in that they are lightweight, easy to work on, and boast electrostatic deflection cicuits.

When one came up on ebay that was right in my hometown, I bid away, but when the bidding approached the $200 dollar range, I backed down and bid on another one. Well, it came today, and I snapped a few pictures of what I got:

I had requested it be packed carefully, and if this was any other set (ie not designed as a piece of luggage) it would have been smashed to pieces. I had requested that the seller open the back of the set and try to stuff some packing around the picture tube. What I got was a piece of foam stuck under the lid, protecting the face of the set. Other than being in a box that was too small, there was no other packing. With all that said, the tv appears to be in great shape.

I was very concerned about the picture tube-in every chassis picture I've ever seen, I never saw the tube supported by anything. Luckily, I now know the tube has a wooden mount inside the cabinet. With a little bit of dusting, the chassis cleaned up nicely. The picture tube must has been stored upright for the last 50 years, as the rubber crt face mount has melted all down the length of the tube. Stalagtites of the goo were hanging out of the back of the set when I got it. The picture tube itself looked like a guttered candle. With a little patience, this all came off with a bit of cleaner.

Looking under the chassis, I can only see that one cap has been replaced. The tubes are all RCA or Motorola, except for a cheasy "long life" unbranded tube. Looks like this set saw little service before getting put aside. Manufacturing date is May 24, 1949. Personally, I can't wait to get into this one. I expected this set to be of pretty cheap construction, given its low selling price, but the quality is really decent. No wonder Motorola sold so many of these.

edit:
Don't see the pictures? Well, I didn't post any as I am having issues with my SD card reader. We'll see if I can amend that later today...

leadlike · #2 10-02-2009, 07:50 AM

Finally! Let's see if I can attach pictures...

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Zenith26kc20 · #3 10-02-2009, 08:24 AM

Love the electrostatic sets! Keep us posted!

stromberg67 · #4 10-02-2009, 08:47 AM

Congratulations!! I am fortunate to have two, both with good CRT's. They also are the same chassis series, TS-4J. There are variations in the chassis through the production life, with many circuit changes. Best of luck on the restoration!!
Kevin

stromberg67 · #5 10-02-2009, 08:48 AM

Oh, forgot to mention that mine are VT-71's.

Phil Nelson · #6 10-02-2009, 12:17 PM

Fun sets. Here are my restoration notes for what they're worth. That was several years ago. I might do some things differently now.

http://antiqueradio.org/motvt73.htm

Sold mine at a swap meet a few years ago, so now all that's left of it is a short video of a Scrubbing Bubbles commercial. We still have three other 7-inch sets in the house, though.

Phil

bandersen · #7 10-02-2009, 01:16 PM

Cool

I'm glad it survived. Few sellers know how to properly pack a TV.

newhallone · #8 10-02-2009, 01:26 PM

I think few sellers know how to nor care to pack anything properly.

leadlike · #9 10-02-2009, 04:10 PM

Thanks for all the comments! I forgot to mention the huge gash in the lid of the case-looks like it was done by a circular saw. Maybe someone used this as a sawhorse. I still can't believe the crt was as "carefully packed" as I requested. I just went back and looked at the old email I sent and I can't see how they would mix that up as they did. I remember when I opened the lid and saw that bit of foam protecting nothing, all I could sarcastically think was "Wow, thanks! My cup runneth over!"

My plan here is to build a ballast on a heatsink like Phil details in his website. It may not look stock, but I would feel much better knowing the failure-prone ballast is out of the picture. Even on a set with apparently so few hours on it, the ballast cage is still pretty toasty looking. I also plan to replace most of the components on this set, as I plan to watch it quite a bit, and on a set this simple I'm sure that when one component fails, the whole set quits. Now, I just need to find a SAMS....

bandersen · #10 10-02-2009, 04:53 PM

You probably have the TS-4J chassis? Here's the early version. I have the other pages too - parts list, voltage readings, alignment instructions too if you're interested.

TS-4J Early page part 1
TS-4J Early page part 2

Those came from a Wallace Telaide which has ledger size pages so I had to split it into two scans. Hope you can read it.

As for the ballast - I sent you a PM with info on where you can get a NOS Amperite ballast tube.

Bob

leadlike · #11 10-02-2009, 05:27 PM

Banderson-thanks for the tip! If you can get the time, I'd like to see the parts list as well. This is a TS-4J chassis, but I'm sure there will be some differences.

bandersen · #12 10-02-2009, 06:20 PM

Here are all my scans

*zenithfan1* · #13 10-02-2009, 07:44 PM

Great looking set! I love these little Motorolas.

bandersen · #14 10-02-2009, 07:57 PM

There are two variations of the TS-4J chassis - Early and Late. An easy way to tell them apart is to look at the Contrast control. The 'Early' just has wires. The 'Late' has some caps and resistors soldered to the pot. I have schematics for both.

leadlike · #15 10-10-2009, 02:06 AM

Banderson, thanks for the link to your scans! That makes things much easier for me. FWIW, my chassis is a late version.

Well, time for a little update:

I started recapping early this week, and just today felt I had done enough to try to power it up. At this point, I had replaced all of the paper caps, the HV tubulars, and the lytics. I was rewarded with a fine picture! After a few adjustments, I was very happy with the result-the crt is nice and bright, indicating its low use.

After running for about thirty minutes, I could see some vertical issues, from loss of sync to some shrinking, but nothing serious enough that readjustment wouldn't bring back the picture. Audio was a little quiet, so I began measuring B+ and saw it was about thirty volts too low. My concern went to the selenium rectifiers, which I planned to remove anyway.

I dropped in new diodes, and wired each of them in with a 50 ohm resistor to create the appropriate voltage drop of the old seleniums. At the next powerup, poof! A little puff of smoke, and I knew the ballast was toast. As I suspected, the section of the ballast that forms a 200 ohm choke, which meets the diode's output, was what snapped open.

Checking my work, the install was correct (proper diode polarity, wiring in it's proper place, no shorts) but maybe the new diode/resistor setup wasn't dropping enough for that poor ballast. Oh well. I did snap get some screen shots, so that will have to satisfy me for now, until I can restore power. I'll post those pictures sometime later today.