Motorola VT-71 restoration (TS-4J chassis, Blonde cabinet)

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Yes, I'm restoring yet another Motorola 7" set This is actually one of the first sets I picked up, but it was really chewed up so I left it on the back burner. The recent acquisition of some nice Amperite ballast tubes got me thinking about so I hauled it out. Also I figure I might as well finish it off while the TS-4 schematic is fresh in my brain.

Here it is as I got it. The cabinet isn't too bad, but the insides The CRT base was ripped off as was the CRT socket. Seems that someone decided to hard wire the CRT to the case. Maybe the old socket developed shorts?

I've already removed the CRT


Also one of the tuning slugs is broken off and a HV pot is frozen. Plenty of ugly old repairs too with big solder globs on the replacement parts.



Finally, no tubes except the HV rectifier (that should have tipped me off to replace it!)


Oddly, the original mask is almost good enough to still use.

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Since the 3 electrolytics have cardboard covers, I decided to re-stuff by cutting them open near the base.


First, I had to remove the cardboard covers. Seems simple enough, but one of them was really, really stubborn. I ended up cooking it in the over @ 300F for 10 minutes to loosen up all that tar!
Next, I cut them open with a Dremel and pulled out the goo.


I was surprised to discover one had already been replaced with a pretty bad match! 30/15/40 isn't exactly 100/60/20


Here they are remounted. I'll glue the covers back on once the set is working properly.

[zenithfan1]

Bravo Bob, another one well done (almost).

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Next, I tackled that frozen HV pot. I cut a slot in the plastic extender to finally free up the inner shaft. Maybe contact cleaner or age melted the plastic ?


I discovered a bad coil in the video amp and had to re-solder one end.


I put a new base on the CRT and replaced the socket. Quite a challenge for me.


Next, I replaced all the wax caps, some mica (I tested them) and out of tolerance resistors (lots of them!)


I replaced all the missing tubes, did some final check, and slowly powered it up.
Nothin'


So, I start testing voltages at various test points - B++, B+ etc. It all checks out. Grrr.

Must be a bad tube or two - right? So I swap out all the tubes from a working set and, viola, audio on channel 6! That one low power OTA station in Chicago broadcasting light jazz.

Which tube was bad?
None of them! I had been referring to a tube placement diagram for the TS-18 chassis instead of the TS-4 chassis
I really shouldn't work on so many projects at the same time!



Still no HV though. I pull the HV cover, turn off all the lights and see a ghostly blue glow coming from the 1B3. I pull it and it's a dud.
That was the only original tube left aside from the CRT.
The only replacements I have is a 1B3/1G3 which is a bit shorter so I need to reposition the feedback coil.
It should be 3/4" from the top of the base.


Bam! I've got a working set . The vertical and horizonal sync are touchy, but I can work on that.


Here's a short video clip of it playing.

Next up, tweaking and restoring the cabinet.

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Originally Posted by zenithfan1

Bravo Bob, another one well done (almost).

Thanks Mark
There's a limit of 18 or so images (and smileys count!) in each post so I broke this one into sections. You caught me mid post

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Originally Posted by Phil Nelson

Bam, indeed. Some folks would have given up with problems like that tortured CRT.

You work fast. If you stop by here for a weekend, I've got some nasty unfinished jobs that you could tackle

Phil Nelson

Thanks, Phil
I dunno about fast. It was about 4 weeks start to finish and I had all the parts on hand.

I have 17 more sets to restore, so your jobs will have to wait

P.S. I'm using lacquer on this cabinet. I think I've finally gotten the hang of it.
Kinda makes me want to strip and refinish the mahogany Motorola I use polyurethane on a while back

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Originally Posted by zenithfan1

Oops! I just couldn't wait to open my mouth It really came along fast it seems, this set really gives me hope on my dead TS 18 chassis. After a couple parts are located I'm going to tackle it. You do great work my friend.

Thanks!
I've done about 1/4 of my TS-18 chassis from that smashed bakelite set. It's a real mess compared to this set so I used the parts I had ordered for it on this one instead.

Still, I expect to get them all running one day.

I'd really love to get all my sets running at the same time, on the same program and take a photo, but I think that'd take more juice than my place is wired for

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Originally Posted by Dave S

Wow! I haven't seen a mask that hadn't melted for ten or fifteen years now.

Yeah, I was quite surprised too - hard as a rock and fragile though.

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I've begun work on restoring the rest of the set.

Here's the original cabinet with the faceplate and control area removed.


I stripped it with CitriStrip and Mineral Spirits. Lightly sanded it, masked off the center portion and stained the rest with "Golden Pecan". I think it's a pretty good match to the original. Once it's dry, I'll used a few coats of gloss lacquer.



The original CRT mask is just too crusty and crunchy to use. So I grabbed one of the last reproduction masks from renovatedradios.com
Apparently the mold broke, but he still has a master molded in hard plastic. You can email a request and when he's received enough, he'll do another run.



I repaired a small tear in the speaker cone using this simple technique



Knobs, knobs knobs! I have 3 Motorola 7" sets that need complete sets of knobs. Mahogany, Blonde, Bakelite. Here's the knobs I have.



Here's my guestimation

Far-left is from a Motorola 9VT1 like this one

The center group of brownish knobs is for the mahogany and blonde. Not sure about the darker/lighter brown or the circular inset color.

Swirled, tan smaller knobs - no idea!

Finally, my lone golden knob for the bakelite set courtesy of Zenithfan1 (thanks Mark!)

If anyone can verify which knobs go with which set, I'd be very grateful. I'm also open to trading. All I need is 3 complete sets.

Here's what various combinations look like on this set. That's my restored photo finish on the control area. Took for freakin' ever to get it right. It's still not perfect, but I've spent way more time than I ever expected on it.
I wonder why Motorola use a photo finish for the front on the blonde sets? Maybe a rare wood was used? The Mahogany set is veneer all round.



Finally, I'm going to try making some custom decals for this set. It's similar to the repro decals sets that are out there in gold lettering, but this set needs brown lettering. Also channels 1,2,3-4,5-6,7,8-9,10,11,12-13.

The idea is that you print onto this special pape and, spray a few coast of clear, gloss enamel over it. Once it's dry, you can float the paper in water to release the decal like normal.
I hope it works out well, I have a few other sets that could use new decals.

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I've also tuned up the set a bit and it's playing better. Here it is playing the opening to "Danger UXB" one of my favorite series

and another of "The Prisoner" opening

It's playing from a DVD player fed into a Blonder Tongue modulator set to channel 3 located about 30 ft away for a signal source.

My DVD froze for a moment in that 2nd video which caused the set to lose horizontal hold for a moment. After it locked again, the whole picture had shifted over an inch or so to the right.
Gotta love analog

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I forgot to mention that I put on a new set of rubber feet from Antique Electronic Supply. They are a perfect match for the originals.

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Originally Posted by Tubejunke

Those look identical to the knobs for a 1940s Fada AM-FM radio that I have.

Interesting...
I found a bunch of knobs in this style at a radio show recently. I figured they couldn't all be from Motorola TVs. They do fit well though.

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Originally Posted by electronjohn

I always enjoy your restoration play-by-play, sir! Hats off to you!

I'm glad you like my style.
Here's another exciting installment!

I managed to salvage the vertical center HV pot extender with a little epoxy cement and it's usable again.


The cardboard sleeve from the cap I roasted in the oven didn't survive the experience. So, I fabricated a replica using a toilet paper roll and glue.
I then spray them all with a little flat black paint - they look a lot darker in person.
I considered masking off that corner of the chassis and touching up the black paint, but decided it wasn't worth it.


Next, I cleaned up that copper plating a bit.


I also replaced all 10 missing HV cage screws. Every set I have seems to be missing at least half it's screws!


Here she is all cleaned up


Next, I tackled the plastic faceplate with some Novus #2


Good as new!


This set is missing the bottom pan and the rear cover. Here's they are from another set. The bottom tray should be easy to fabricate with some sheet aluminum. I'm not sure about the steel rear cover other than using a piece of sheet steel and giving my drill press a real workout.
Any ideas?


Finally, I tried to make some decals. I've attached the image file I created.
I printed that out onto some special decal paper and sprayed it with several coats of clear gloss acrylic as indicated. Looking good so far.


Ugh, I accidentally ordered the wrong decal paper Opaque white backing instead of clear.

On the bright side, it seems to work fine on my scrap sample.


Here's a preview of the set while I wait for the proper decal paper to arrive. I still have a little work to do on the cabinet. Touch up the top front finish, apply the decals and give it a couple coats of lacquer. Also the CRT isn't firmly seated yet.

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I got the proper clear decal paper and it works great! I think being able to create my own decals is going to come in real handy.
I can't print the common "metallic gold" color, but a lot of reproductions for those are already available.



Finally, it's lacquer time !


I have some upcoming projects that will require a real fine, high quality lacquer finish so I'm going to try out this hand rubbing process.
Basically, you use sandpaper, steel wool, pumice and rottenstone to buff the heck out of that lacquer.
Has anyone tried this technique before?

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Originally Posted by edison64

So where did you find the decal paper, I cant find any anywhere. sure would like to complete my MOTS, It's funny, most of the Motorolas i have or have seen need decals, whereas other manufactuer sets from the same period the decals and markings look new.

I used this place
Inkjet clear