Motorola 19K1 restoration
 

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.
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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.
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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.
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Dual speakers and integral antenna
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Only two screws were left holding the chassis in :eek: That's why I always remove chassis and picture tubes for transportation if possible.
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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?

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 :scratch2:
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The base reads 'factory rebuilt'. Anyone know what the "S" on the neck means ?
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It's good :banana:
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A little size comparison. 5AXP4, 19AP4 and 10BP4. I've never work with such a large CRT before!
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Here's the chassis. It appears to be all original.
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The tuner is quite a piece of work
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There's a crazy mix of tube brands and about 40% are weak or bad. I bet this set saw a lot of use.
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I can't wait to see those orange knobs light up again :)
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Roger that - don't hug the jug :yikes: http://www.jawaspot.com/smilies/shocking.gif http://www.jawaspot.com/smilies/spooky/tombstone.gif

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 ?

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.

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.

Some manufacturers coated that glass portion of the CRT with some sort of insulating paint, beyond me as to why. I didn't think glass could be inproved upon as an insulator. The pic is of a 16GP4 that was coated.

Initially, I was going to remove the remains of the existing socket and replace it. Possibly with a donor from a dud tube.

Now that I've inspected it closer, I think I'll try to build it up with something like 2-part epoxy. All 5 pins and the center key are in good shape. So is the entire circumference of the end of the base.

Reading all the warnings on that CRT are making me a little nervous of messing around with it.

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.

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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 ?

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

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

Interesting. That portion on this CRT seems to have maybe a hint of old coating. Otherwise, just glass. Maybe they removed it during the rebuild process ?

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) :headscrat:

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.
http://www.bobandersen.com/images/mo...1%20cap-01.jpg

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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

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.

I do have a couple vintage RC bridges and will try them out. The ranges don't go anywhere near 2,600 uF though.

The parts from Mouser and a bunch of NOS tubes have arrived. Now the fun can begin :D

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OK, finally back to the 19K1.

First up, a little cleaning. Luckily, the dust and dirt comes off easily with a soft brush. I followed that up with a rag and a little mineral spirits.
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That's better. I really like that copper plating - not a speck of rust to deal with.
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The flyback looks to be in excellent condition :thmbsp:
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Only a couple issues so far. One, a crude electrolytic repair. A wire to the right was cut, the ends stripped and the capacitor lead spliced in. I think I'll replace the whole wire and restuff the electrolytic can.
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Two, the yoke & focus coil plug and socket are damaged. I posted in the classified section for a replacement. Plan B is to replace it with a more conventional octal plug & socket.
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Otherwise, just loads of capacitors to replace. The wire-wound sand power resistors are in miserable condition too.

Dah-Yum, I'd be tempted to leave it outta its case...Dat's PURTY !!!

I have those octal plugs if you need one. They're actually battery plugs, using a pilot hole instead of a key--they were used in AB battery packs.

I found some more damage and crude repairs around the horizontal output tube. The replacement resistor fell off when I touched it due to some very poor soldering. The socket is in bad shape too. Pin 8 is broken off and I need to solder a capacitor to it. It might be best to replace it and all the surrounding components :scratch2:
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I also noticed that the Sams for this chassis shows two doorknob capacitors with a resistor between (PI filter). I've only got one. Maybe another crappy repair job ?
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Yeah, but someone would probably get a real charge out of the 19AP4!

John

The cabinet is actually still back in the antique shop waiting for Nixer to pick it up. He's over your way in Tennessee. I'm only going to restore the chassis and somehow get it over to him.

I've seen you mention some folks that restore cabinets in other posts. Maybe they could fix up this one :scratch2:

Oh yeah, they do look like battery plugs. PM Sent.

Ouch - for sure. Here's the itty-bitty little 5AXP4 I'm using while restoring it.
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Will the 5AXP4 handle the HV of a 19" tube?
Does that set use a doubler circuit for the HV?

I tried one in a 21" rectangular set and it arced inside from too much juice, the rectangular test tube (8YP4?) worked OK though.

Good question. Nope, no doubler.

According to this handy website we have the following.

CRT, Typical, Max
19AP4, 14 kV, 16 kV
5AXP4, 14 kV, 19 kV
8YP4, 16 kV, 22 kV

I'm a little surprised. I though the 19AP4 would be a little higher than that. I need to rig up an anode cap, but otherwise should be OK.

I'll find out for sure soon I hope :D

Progress update
 

I've been making steady progress in between other projects.

First off, I found where that second doorknob capacitor should be. I think I can dig up another good one from another set. Meanwhile, I'll just stick with this one.
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I've replaced the power resistors and electrolytics and most of the paper caps.
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Time to do a little power up test with no tubes. No smoke and the transformer voltages look good.
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One of the control lights lit up, but I think the other is burned out.
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Next, I popped in a few tubes including one of the paralleled 5U4 rectifiers and slowly cranked up the variac.
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All the voltages looked good, but I detected a nasty smell after a few minutes. A little sniffing located this fried capacitor. Time for a little more recaping :yes: All told, things are looking very good for a first power up.
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Very nice progress on that set!

Thanks. I hate the first power up after some major work. I'm always bracing for a cap to pop in my face. So far it's never happened though - just some occasional smoke :D

I've finished all the recapping and resistor checking except for the HOT area.
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These old sand power resistors were especially crappy.
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That leaves this corner to deal with. I've cleaned out most of the debris and smoky residue. I was able to replace the damaged pin #8 fairly easily so no need to replace the whole socket. I found no less than 4 cut wires associated with the HOT circuit so there's no way this set had a picture.
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Even the fuse holder is broken :no:
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Perhaps someone gave up on the repairs. I was expecting to find an open coil, but so far so good.

I also just received replacements for the damaged yoke & focus coil plug from some helpful forum members.
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I won't be long before I can try a full power up.

Mine (I've got the console!) is on my bench - the horizontal section's giving me fits and it syncs like crap :( hopefully i'll get it sorted out this fall.

The knob on the lever is the fine tuning adujstment, for when the cover's off. It's a weird set, that's for sure...

(And yes, a 25L6 with a step up auto XFMR for the vert output. Like I said, it's a weird set...)

Yeah, it's a weird one alright. I'm in the process of rebuild the whole horizontal output circuit. I hope to fire it up again in a day or two.

Luckily, the oddball valued 400pF mica cap is still good. Every other component needed to be replaced.
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Here's that burnt up corner all rebuilt. I used a flameproof metal oxide resistor so hopefully no more fires.
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Speaking of fires, looks like the yoke connector got cooked pretty good too.
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Another progress update
 

The focus coil leads were deteriorating so I reinforced them with heatshrink tubing.
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The horizontal yoke leads were even worse. Basically everything to do with the horizontal on this set has been mutilated :tears: So I threaded some new cloth covered wires up into the yoke. I also found that the two 560 ohm resistors were 760 and 810 and replaced them.
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Now, I could finally rebuild that plug. I was able to polish off most of the gunk from the metal shroud.
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I'm going to try another power up tonight.

The Flyback looks a little cooked on the one side, or is it just black from static attracted dust? Hopefully it wasn't the cause of the meltdown.

It is darker on one side. I think the culprit was the missing doorknob capacitor though. It would have been right next to the darkened area. I'll find out soon enough.

Nuts. There's still something burning up in that corner even with the HO tube pulled.

None of the components are getting hot though. I think it's either the tube socket or the wiring.

I'm tempted to leave it on until I can definitely see some smoke to pinpoint it, but am afraid of burning out something.

Perhaps the terminal strip is charred/arcing?:scratch2:
jr

That's a great idea!

I unlaced the wiring harness and separated the wiring, but that didn't make any difference. I don't think it's the tube socket either. That leaves the terminal strip or the stuff on the top of the chassis (horizontal width coil and flyback).