1948 (TS-4H) Motorola VT71 restored! - Videokarma.org TV - Video

bandersen · #1 06-05-2009, 09:45 PM

zenithfan1 inspired me to post a little photo diary of my VT71 restoration.

Enjoy.

Arrival. It's in good shape aside from all the knobs being wrong.

Pretty much all original.

Ugh. Need to re-solder a CRT pin.

Apparently, this is the melted CRT mask. It hit a few tubes and the speaker

I really hope I never need to do this again!

Refinishing the cabinet. Citristrip is my favorite stripper lately.

Applying new decals from radiodaze.

The usual. Replaced the selenium with silicon. Wax caps with poly. And HV caps from Allied.

Ready to fire up. Got those knobs from a blonde VT71.

First signs up life using a 7VP1 CRT from an RCA WO-56A scope.

Seems safe enough to hook up the 7JP4

Old components. Those two caps in front were the source of much hair pulling. They came from the vertical oscillation/sweep circuit.
I assumed that mica caps rarely go bad. Boy was I wrong.

Replaced the 12AT7 and got my 1st stable image

Here it all is back together. I still need to track down a fine-tuning knob and do something for a CRT mask.

Here's some of the gear I used.

Dan Starnes · #2 06-05-2009, 10:48 PM

Great post,, loved it!!!

***Eric H*** · #3 06-05-2009, 11:07 PM

Very nice, that stuff isn't foam however, it's the infamous VT-71 mask that is always melted, it's water soluble, not that that's any help when it's on a speaker cone!

Renovated Radios makes a repro mask now for about $43.

bandersen · #4 06-05-2009, 11:28 PM

Quote:

Originally Posted by Eric H

Very nice, that stuff isn't foam however, it's the infamous VT-71 mask that is always melted, it's water soluble, not that that's any help when it's on a speaker cone!

Renovated Radios makes a repro mask now for about $43.

Wow! They can really melt all over like that? I guess that makes more sense than a maniac with an insulating foam canister

Tube TV · #5 06-06-2009, 05:43 AM

Looks great ! , the VT-71 is next on my list to get .
They sure look like a fun set to restore .

So how long did it take from start to finish ?

bandersen · #6 06-06-2009, 05:55 PM

Quote:

Originally Posted by Tube TV

... So how long did it take from start to finish ?

About a month working ~ 2 hours a night. Would have been a week less if I had replaced those mica caps from the start!

Phil Nelson · #7 06-18-2009, 08:30 PM

Quote:

Originally Posted by bandersen

Would have been a week less if I had replaced those mica caps from the start!

For a long time, I ignored micas in the belief that they were almost always good. I learned different on my 630TS when a pal tipped me about checking a couple in a known trouble area.

Like many other 60-year old things, micas are starting to show their age. I don't shotgun them without testing, as I do paper caps, but I'm alert that they don't all stay perfect forever.

Nice job. I'm a Citri-Strip fan, too. And I will even forgive you this time for using polyurethane <holds up garlic, makes sign of cross>

Phil Nelson

bandersen · #8 06-18-2009, 10:49 PM

Quote:

Originally Posted by Phil Nelson

Nice job. I'm a Citri-Strip fan, too. And I will even forgive you this time for using polyurethane <holds up garlic, makes sign of cross>

Phil Nelson

This was actually the 1st time I ever used it. I decided to give the whole line of Behr water based products a try on the project. The results are OK and cleanup was a snap, but it's not as good as more traditional products.

I've used hand rubbed tung oil and spray lacquer in the past. What do you recommend?

Phil Nelson · #9 06-28-2009, 01:19 AM

Quote:

Originally Posted by bandersen

I've used hand rubbed tung oil and spray lacquer in the past. What do you recommend?

Normally lacquer -- the same thing originally used for the majority of old radio and TV cabinets. Easy to use, dries fast, and can be reversed if you don't like the outcome and want to start over. Poly can provide a very shiny finish, but if you've ever tried to strip it, you'll know why it's not my favorite.

Phil