Motorola 19K1 restoration - Page 5 - Videokarma.org TV - Video

bandersen · #61 08-23-2010, 11:33 PM

That's the "Horizontal Size" control and is very much a pain to get at. Once this chassis is back in the cabinet, all the adjustments will be even tougher to get at. If you look back at the start of this thread, there's an original ad where they promote the idea that only two controls are needed. We'll see about that.

bandersen · #62 08-25-2010, 12:08 AM

Quote:

Originally Posted by nasadowsk

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...)

Adjusting the hor. lock really helps with the sync on this set.

I took a closer look at the channel selector and still don't get the fine tuning. It looks to me like the only adjustment is the tuning slug for each channel. That level with a hole in it just acts as a guide for an adjustment tool. Is that what the service manual means by a fine tuning control

I added a second HV cap and a carbon comp 470K resistor to form a PI filter like the schematic shows. I used rounded solder blobs and it seems to work OK. No arcing so far. I was able to get most of the dark crud off the flyback too. That red splattered stuff is high voltage insulating "paint" applied during some repair long ago.

This seemed to produce a brighter, crisper picture, but two dark lines appeared on the left. I cranked the hor. drive all the way down (clockwise). That mostly got rid of them but the brightness suffered. I tried a couple different 6W4s, but that didn't make much difference. Also, the horizontal width coil is warm - not sure if that's normal. Perhaps I should remove that second HV cap after all

bandersen · #63 08-25-2010, 03:51 PM

I decided to try out the 19AP4.

That's a little disappointing - just a faint smudge. I guess 12kv won't cut it. The Sams doesn't mention the HV value, but I found a schematic in a Wallace Telaide that shows 17 kv.

I've contacted Moyers to see if they have a Motorola 24C792691 or Merit HVO-6 replacement. I'll do some more checking in the meantime.

Ralph S · #64 08-25-2010, 04:09 PM

In your last post you said the picture tube was a 19KP4. I can't find a data sheet for that number, yet earlier pictures show a 19AP4A which is a standard tube. If it's really a 19AP4A that your testing, did you forget the ion trap? That's an easy thing to overlook.

Ralph S

bandersen · #65 08-25-2010, 04:46 PM

Nice catch! I meant 19AP4. And, yes, I completely forgot about the trap magnet

You get spoiled using the little test CRTs which don't need them.

After adding the ion trap magnet and a whole lot of tweaking to it, the centering magnets, focus coil, etc. I got these images. The brightness is cranked all the way up and the hor. drive adjusted for the least noticeable dark bar on the left. Too bad Sams doesn't include any directions for adjusting the controls.

It's a little disconcerting feeling all my arm hairs tingle when I reach for a control

kvflyer · #66 08-25-2010, 05:41 PM

Hmmm. Looks like it works!

bandersen · #67 08-25-2010, 06:08 PM

Yep - just needs more HV and a few bits need to be repaired like a broken fuse holder and loose lamp socket. Another batch of parts arrives Friday.

RitchieMars · #68 08-25-2010, 06:17 PM

Hey, that's looking really good! Seeing that big CRT from the side, it really dwarfs the chassis in comparison. Kinda scary!

What do you suppose is causing those dark vertical lines?

bandersen · #69 08-25-2010, 07:14 PM

Thanks. It sure is scary. I'm used to working with CRTs half that size not to mention that most of the outer surface is at 12,000 volts!

I have those dark lines to some extent on a few of my sets. They can be caused by a bad damper tube or too much horizontal drive from what I've read. I imagine there are several other components that could be off or miss-adjusted that cause them.

Phil Nelson · #70 08-25-2010, 08:00 PM

Looks promising. Be careful around that thing!

Re the lines on the left side, if all else fails, read up on Barkhausen oscillations. I actually had that problem once. Even if it's not the cause, just reading about the topic makes you feel smarter

Phil Nelson

bandersen · #71 08-26-2010, 01:49 AM

Quote:

Originally Posted by Phil Nelson

Looks promising. Be careful around that thing!

Re the lines on the left side, if all else fails, read up on Barkhausen oscillations. I actually had that problem once. Even if it's not the cause, just reading about the topic makes you feel smarter

Phil Nelson

I'll be removing that big CRT while I tinker with the set some more. I wanted to make sure it was really good and see if the problems I saw on the little CRT would persist.

I saw that trick on your site with the magnet in the HV cage. I waved a magnet around this 6CD6 tube, but it had no effect. Oh well, there are still plenty of other components to tinker with in the horizontal circuitry.

Phil Nelson · #72 08-26-2010, 01:17 PM

Sure, I'd check obvious things first. For what it's worth, the lines in my Halli T-67 were cured by substituting horizontal output tubes. One of my books also mentions trying a circular magnet (such as an old ion trap magnet) around that tube.

Phil

bandersen · #73 08-26-2010, 03:13 PM

It test really good in my Hickok, but I've seen plenty of comments that the only way to really test it is to try it in a set. I don't have any other 6CD6s on hand so I picked up a couple on eBay.

miniman82 · #74 08-26-2010, 07:22 PM

Shoot, I have a bunch of those all you need to do is ask! 6DQ5's too.

bandersen · #75 08-26-2010, 07:50 PM

Quote:

Originally Posted by miniman82

Shoot, I have a bunch of those all you need to do is ask! 6DQ5's too.

Oh well. I'll keep you in mind for the future. I got two of them plus a 19BG6 for $0.99.