Motorola 19K1 restoration

[bandersen]

Last fall I posted a whole bunch of pictures from a local antique shop packed with vintage TVs and radios. I stumbled across TheNixer's classified ad for a bakelite Admiral 24A12 about the same time and hooked them up. He got the itch for another set, looked through my pictures, and this time picked up a 1950 Motorola 19K1 AKA 'The Van Dyke'.

Here's an original ad on tvhistory.tv

Since it's only a couple miles from me and I've never had the chance to work on a set like this before, I volunteered my services to get it running again.


The cabinet is in rough shape like every set at that shop. Someone there really liked to stack heavy crap on the set and gouge into them. The doors and sides are in much better shape. The door pulls are missing though. Does anyone out there have the same set or know what pulls are appropriate ? I'm only going to be working on the chassis. I hope someone else can do a nice job on that cabinet.




The insides are in much better condition. I was a little concerned about the 19AP4 when I saw the damaged base, but it tests very strong. It's a factory rebuilt CRT with an 'S' stamped on the neck. I've never work with such a large CRT so am being extra careful. I plan on using a little 5AXP4 during the restoration.

Only a fragment of the back remains.


Dual speakers and integral antenna


Only two screws were left holding the chassis in That's why I always remove chassis and picture tubes for transportation if possible.

[leadlike]

I kinda liked that Moto set when I saw it in those tv shop pictures-the knobs are pretty neat, plus you get to work on that cool giant crt. Just avoid temptation and DO NOT give that metal crt a big hug while it is powered on, okay?

[bandersen]

Originally Posted by leadlike

I kinda liked that Moto set when I saw it in those tv shop pictures-the knobs are pretty neat, plus you get to work on that cool giant crt. Just avoid temptation and DO NOT give that metal crt a big hug while it is powered on, okay?

Roger that - don't hug the jug

[bandersen]

I've had it hope for a couple days now. Here are some more details.

First off I was concerned about the damaged CRT base, but it turns out the tube is just fine. That's really good, I've heard these are few and far between.

The widowmaker. I'm not sure what they mean by "insulating coating". Seems like just glass to me




The base reads 'factory rebuilt'. Anyone know what the "S" on the neck means ?


It's good


A little size comparison. 5AXP4, 19AP4 and 10BP4. I've never work with such a large CRT before!


Here's the chassis. It appears to be all original.


The tuner is quite a piece of work


There's a crazy mix of tube brands and about 40% are weak or bad. I bet this set saw a lot of use.


I can't wait to see those orange knobs light up again

[Phil Nelson]

Originally Posted by bandersen

The tuner is quite a piece of work

Can't really see how it works . . . wafers?

Phil

[bandersen]

Originally Posted by Phil Nelson

Can't really see how it works . . . wafers?

Phil

Yes, it appears so. What I'm not sure about is the hole in the chassis for each channel. There's an arm with a hole in it sticking out the the selector shaft. The hole lines up over the selected channel. Perhaps it's just an aid for aligning the coil ?

[TheNixer]

I was finally able to get back to my e-mail this weekend and found two e-mails from Tom. Wow is he a nice guy! He really helped me out with the details of this set. Here are the photos he provided. I can't tell if it's spelled VanDyke or VanDyck. Either way, it's one great looking set.

Bob, thank you for all the photos and attention you've already given the set. It's all much appreciated, thank you.

[DaveWM]

what is the game plan on that CRT socket? leave and use as is, replace it, or try to build it up somehow? I assume no hurry on what to do until the set is closer to working.

[bandersen]

Originally Posted by TheNixer

I was finally able to get back to my e-mail this weekend and found two e-mails from Tom. Wow is he a nice guy! He really helped me out with the details of this set. Here are the photos he provided. I can't tell if it's spelled VanDyke or VanDyck. Either way, it's one great looking set.

Bob, thank you for all the photos and attention you've already given the set. It's all much appreciated, thank you.

Excellent! Tom is responsible for pointing me to this forum a while back


"...2 control knobs on front panel are all that are needed for normal operation..."

Ha! Pull off those two 'simple' controls and you'll find all the other adjustments lurking


Cool that the tuner has UHF capabilities. I counted 15 positions when I rotated it. If we're really lucky, it has the right parts to pick up some of the few remaining analog UHF broadcasts in our area.
I really hope I won't have any need to go poking around in there.
(click for hi-res version)

[bandersen]

I fired up a more accurate tester and went through all the tubes. I was amazed to find 13/22 tubes are bad. Either failing on transconductance, gas or grid leak! Even both the 6AL5s are really dead - almost no emission. Typically, I find one or two bad and a few weak tubes.



All the crucial tubes are good though - some relatively new. Like the 6CD6 HOT, both paralleled 5U4s, 6W4 damper and 1B3 HV rectifier. I wonder if that was enough to produce some sort of image or sound and the owner kept running it into the ground ?

[Phil Nelson]

In a few radios, I have found tubes that looked pretty dead on a tester but still performed surprisingly well. You can think of various scenarios where someone might play a TV to death as long it made sound. Older person with poor vision, can't see the picture anyway. Uncle Joe listens to ballgames while working in the shop. Family gets new TV, but lets the kids have this in the basement to watch cartoons . . . .

Phil

[zenithfan1]

That's a nice looking set. I have faith in your refinishing skills, I bet it turns out great!

[bandersen]

I haven't run into anything like this before. It appears to be a huge non-polarized capacitor, but the rating is strange. 3VNP 1.0 ohm 60 Hz. Would that be 3 volts non-polarized with an impedance of 1 ohm @ 60 Hz ?

I plugged 60 Hz and 1 ohm impedance into this site and came up with 2.65258 mF (about 2,650 uF) :

Any thoughts on what to use for a replacement ?

Mouser has some 2,200uF non-polarized caps. Maybe that's close enough ?

It's C4 in the schematic.

[jeyurkon]

That's certainly what it seems to be. I'd think the 2.2 mF caps would be close enough. Probably well within the tolerance specs.

John

[leadlike]

This is a situation where a cheap cap checker would come in handy. You can test for unknown values simply by checking where the eye tube closes on the dial scale. All that aside, that has to be the most bizarre method of labeling a cap I have ever seen.