Restoring a Motorola 12VK11R - A Beginner's Plea for Guidance

[tombeiter]

Hello all,

I just joined. I'm sure you are bored silly by the number of people who find an old tv at an estate/garage sale/curb and join this forum looking for guidance, but here I am!

I did some preliminary reading here http://videokarma.org/showthread.php...hlight=12VK11R regarding this same model.

I broke the cardinal rule of plugging in an old tv, but not having money for a variac and even less patience, I pulled the chassic from the cabinet, placed it in the middle of my driveway away from all flammable objects and used a really long extension cord to plug it in. Nothing. Well, one tube glowed. I did leave it plugged in for about 10 minutes to see if it just needed warming up, but still nothing.

So, my intention was to start by replacing the capacitors, but I'm wondering if there isn't a first step in determining whether the CRT is even still functional. I see there are CRT testers on eBay ranging from $15 to $135. I'm wondering if the $15 model is sufficient or the more expensive model is required or if there's another way to determine the status of the CRT.

Also, I'm missing the center post knob on the right channel selector. Any chance of finding a replacement for this?

I've uploaded some pictures of the cabinet and chassis here http://videokarma.org/album.php?albumid=601

The chassis is a model TS-23B and has a manufacturer's date stamp of 1948 or 49, the last digit is hard to read.

Currently, I have the chassis pulled and a newer 13-inch tv inside the cabinet, but I would like to take a stab at getting the original tube working.

Any advice, guidance, comments, or jeers gratefully accepted.

Thanks for your time,

Tom

[ctc17]

Dont worry about the variac, I have always hard started old sets and never had a problem.

As you know first thing is to check the crt and see if you have anything to work with. Then check the power transformer and inspect the flyback as best as you can.

If all that works good then its cap time.

Losts of good videos on youtube by several of us bringing old bw sets backs to life.

[tombeiter]

Thanks for the advice. I will definitely check out the youtube videos. Any recommendations on a CRT tester, keeping in mind a limited budget?

[Sandy G]

ALWAYS glad to have another new "Addict" to the field of TV/radio restoration...Welcome ! But PLEASE Be Careful, they CAN & WILL "Bite"...

[bandersen]

A simple early CRT tester like the B&K 440 or 445 should be sufficient for testing the CRT. I wouldn't use use the rejuvination function though. It's really crude and could damage a CRT.

BTW I have a junk TS-23 chassis I'm in the process of scrapping. I'm saving all the useful bit in case you need any parts.

[tombeiter]

Sandy G: thanks, and I will be careful. I follow the advice of keeing one hand behind my back when tinkering with electronics!

banderson: Thanks for the info on the tester and I appreciate you hanging onto the parts. If anyone comes across an extra Motorola center knob, I'll gladly pay you for your trouble and shipping.

Tom

[tombeiter]

I found a "tube brightener" attached to the back of the CRT. See here: http://videokarma.org/picture.php?al...pictureid=3280

Did those work or was it a clever upsale to the consumer? And should I remove that?

[bandersen]

That depends on what you mean by "work". Yes, they can make a worn out CRT produce a brighter picture, but they will also shorten it's life. That's because they work by increasing the filament voltage 20-30%.

I'd remove it and see what kind of picture it can put out.

[tombeiter]

I did try removing it, but right now, I'm not getting anything. I need to pick up a CRT tester before I go any farther. Hmmm, I wonder if the tube brightener was the death of my tv.

[Phil Nelson]

Absent a CRT tester, you can at least test the filament for continuity. In this article, scroll down to "Checking Tubes Without a Tester:"

http://antiqueradio.org/FirstStepsInRestoration.htm

In this section are a number of articles about restoring various old TVs. None of them exactly matches yours, but you can see what's usually involved:

http://antiqueradio.org/restoration.htm

This article has general info about replacing capacitors, if you need it:

http://antiqueradio.org/recap.htm


Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[DavGoodlin]

Tom,
I built an EICO 635 tube tester in HS. It came with a BW CRT test socket on a 3 ft harness. If you do not have a tube tester, this could be both. It will allow you to "wake up" the CRT by leaving it on. Of course, it does not have a rejuvenate function.

The first TVs I tinkered with were Motorola of this vintage and I reserve a special fondness for anything bearing the sinewave M or batwing logo!

Good LucK!
Dave