I separated the vertical windings from the VOT and still no HV.

I'm at a loss right now.

I do get a 1/4 long purple arc on the top cap of the 1B3GT tube. So does that mean I have good HV to that point?

Thanks.

Kevin,
The 1B3GT socket is in great shape. It must be the lighting.

Any chance there's a carbon trace that's formed from your CRT's second anode button to the dag? It's a little strange how this problem showed up after switching from the test CRT to the original. I'd even be tempted to check the HV with lead disconnected from the CRT, although I'm not sure it that's a good idea. Maybe old_coot88 can chime in on that thought.

Kevin,
I switched back to the test CRT a while ago. It was easier to flip the chassis over to get to test points and to help isolate things. With both the regular and test CRT's I get the same result.

I appreciate you hanging in here with me and offering suggestions. Thanks.

It's very unlikely that this problem is related to the yoke (if it was, you wouldn't have gotten that healthy arc off the 1B3 connector).

More likely there's a leakage path from the HV source to ground that's lugging down the HV.

First try disconnecting the anode connector from the CRT. Does the HV come up any? If not, then the leakage path is from the 1B3 socket area to ground (and is probably the source of that arcing you heard).

What is the highest Resistance (ohms) range on your multimeter? If it'll go to 20 megohms or higher, try measuring from the 1B3 filament winding to ground. It should show infinite resistance (open circuit). Any indication at all would indicate leakage sufficient to drag down the HV.

Sometimes the insulation on the 1B3 filament winding will break down and arc through to the flyback frame. (The filament winding is one or two turns of thick wire wrapped onto the frame). Or possibly a leakage path has developed in one of the 1B3 socket mount standoffs.

I disconnected the anode connector from the CRT and the voltage did not go up at all.

I check the filament winding to ground with the 200M setting on my multimeter. It read infinite ohms.

I'm including 2 pictures of how the 1B3GT is mounted and the filament windings.

Is there anyway to test if the filament windings are breaking down? I don't hear any arcing or buzzing or smell any ozone.

http://i1060.photobucket.com/albums/...psqyx9hmma.jpg

http://i1060.photobucket.com/albums/...psnaif0bm6.jpg

At this stage I would try to determine whether the 1B3 filament is lighting. In a darkened room, looking upward from the underside of the tube, the filament should be visible glowing a ruddy orange. If it isn't, one of the filament pins may not be making connection in the socket.

Another possibility - the 1B3 may be gassy. Is there a hazy blue glow filling most of the tube? Does it feel hot to the touch after running a few minutes?

In a darkened room, I looked up into the 1B3GT and saw the ruddy orange glow of the filament. Also there was a ring of blue haze just below the top metal piece that's inside.

I have a bunch or other 1B3GT tubes and I tried at least 4 to 6 others. They all had the ruddy glow and the blue hazy ring.

Because I can draw a 1/4 inch purple arc off the top of the 1B3GT tube, does that mean I have good HV? I'm thinking so or we would be looking elsewhere.

Again, thanks for all your help.

The blue haze could mean it's got a load on it, I would be suspicious of a short inside the metal cup on the bottom of the socket, my Zenith Porthole uses the same setup and it was tricky to get it back together without problems.

If the new resistors are too fat they might be arcing, also not sure if metal film resistors will work the same as carbon comp in that application.

You might try just popping the socket out of the cup and see if it works.

It means you've got at least 10-12 KV of unrectified pulse going to the 1B3, which is good. And there should be 12 KV or more of rectified DC coming out of the 1B3, which isn't happening for some reason.

After a few minutes running, is the 1B3 hot to the touch, like uncomfortably hot? If so, there's gotta be a leakage path to ground that's not showing up with the ohmmeter check.

Try removing the doorknob cap so the socket floats free and see what happens.

OK guys here is the latest checks.

I took the socket out of the metal housing which is attached to the top of the door knob cap. I then used a craft stick to hold it up away from the metal. I also had to unsolder and disconnect the lead from pin #7 that is soldered to the cup. I made a small extension so I could clip it back to the metal cup. I had no difference in my HV.

I then disconnected the wire lead from the metal cup, thus taking the door knob cap out of the circuit and when I tried it, my HV jumped up to about 6800v. There was also a small "squealing" coming from the flyback area, but no arcs were seen in a darkened room. Also I didn't see the blue haze in the 1B3GT tube either. I didn't want to run it much like this. BTW, these tests are done with the test CRT so I don't have the capacitance from the standard 14" tube.

I'm beginning to suspect the door knob cap.

http://i1060.photobucket.com/albums/...pswhuwc50q.jpg

It was the doorknob all along, looks like. Good sleuthing bro. The squealing may be the hor. frequency is off. HV may increase further once that's corrected and the doorknob replaced.

Yeah, I had lots of help with this one. Thanks everybody.

Now I gotta find a new 500pf 20Kv cap!

If you want, you can run the big CRT without the doorknob temporarily, since the dag already provides a few hundred pf of capacitance. There'll be a slight voltage drop across the 1 meg resistor, probably not enough to notice.

Looks like you found the problem. :thmbsp:

Can anybody explain to me why they reference the bottom of that doorknob to the plate of the damper? I know some of the older sets had it going to ground, so it was in parallel with the dag coating. So if the doorknob is leaking, there's effectively leakage between the HV and the 210V supply.

I just might do that. I'd like to work on the alignment next.

Seems like the only advantage is that the voltage across the doorknob is a bit lower (by the B+ value). But it shouldn't make any difference in the grand scheme of things.
In the old sets with metal bell CRTs, there was no dag system to filter the HV, so doorknobs served that purpose.

But when all-glass CRTs with inner & outer dag came along, doorknobs weren't strictly needed but were sorta "grandfathered" along by convention for a while. Seems like, anyhow.:nerd: In the set being worked on here, the doorknob serves mostly as mechanical mount for the 1B3.

One way to further account for that grandfathering is that many makers used the same chassis to drive a wide variety of screen sizes, and for a while there was a mix of types (by screen size) available...IIRC one of the later metal tubes to be in use was the 24".

I was thinking the B+ also adds in series with the 1B3 rectified pulses, for a B+ boosted HV? Not sure it they were that hard up to get an extra 210v to the CRT anode, but it sure seems like the rectified flyback pulses are being stacked on top of the B+, relative to ground.

But the HV value itself isn't gonna change whether the filter cap is grounded to chassis or to B+. Remember, it's an RF ground either way (the spikes being filtered are RF).

With the cap grounded to B+, the DC across the cap will be lower by the B+ value. The HV itself willl be unchanged.

Rca built a 27" set, using the metal rectangular 27MP4 around 1954. IIRC, the rebuilt CRT was $66.00, with only a 6 month warrantee. There was also a 30BP4 available for $76.00, with the same 6 month warrantee. :thmbsp:

I could use a couple of those NOW!

.

That's probably why there are so few of those sets around today. :yes:

There was a 27" all glass tube in the later 50's, Magnavox made quite a few sets with them.

On the subject of doorknobs, plain filtering wasn't the only purpose they were used for. They were also used in doubler and tripler HV supplies, e.g., the projection sets of the late 40s, etc.

While I'm waiting for the door knob cap I thought I'd do a little cleaning up on the cabinet.

I washed it inside and out with some Dawn dish washing liquid and water using a small terry hand cloth.

Then I wanted to polish it up, right? Well I looked at different videos and so on and tried these products to get that high shine on this Bakelite cabinet.

http://i1060.photobucket.com/albums/...pstr2uajin.jpg

I tried the Brasso, followed by the Gorhams followed by the wax and it didn't seem to help with the shine. I know the top layer is where you wnat to shine and I didn't go through that. Here is a picture of one side where I tried several products.

http://i1060.photobucket.com/albums/...pshipgohkn.jpg

the largest circle was just using the wax, the next smallest was using Mothers and wax, and the smallest was using Gorhams and wax. In reality, not much difference between the three.

Here is a picture of the top. Yeah, it has a water stain. I tried Brasso, Gorhams, followed by 2 coats of wax. The finish is disappointing.

http://i1060.photobucket.com/albums/...ps8wjccn4r.jpg

http://i1060.photobucket.com/albums/...psa1vuqyae.jpg

My big question is how much "elbow grease" does it take to shine this thing up? Am I not rubbing long enough? I usually go about a minute using medium light pressure with each product. Do I have to rub like 5-10 minutes on each section?

What am I missing? I do not want to use any sandpaper at all. I find it really hard to believe that I'm rubbing though the top layer.

Any ideas from those who have polished Bakelite to a high shine?

Forget brasso. It has ammonia in it and can dull the bakelite. It's the old brasso in a metal can that works well. I've used novus #2 and simichrome with good results. Also Maguire's cleaner wax with contains a mild abrasive. Brown shoe polish or stain can help bring some color back to faded bakelite

Bob,
Did I do harm to the Bakelite using the wrong kind of Brasso?

OK, I'll stick with the Maguires.

Thanks.

I doubt the ammonia will harm anything once you cleaned it off with some other polish. Bakelite resins aren't easily dissolved, but years of sun exposure can really take it's toll. Too much sun slowly oxidizes away the surface resins, which then leaves the Bakelite filler material somewhat exposed on the surface, and that leaves a grainy wood like appearance.

Here is a close up picture of what I'm up against. The nice area was behind the plastic bezel for the knobs on the front of the set. This one used the flash:
http://i1060.photobucket.com/albums/...pssgrf2la2.jpg

This one there was no flash:
http://i1060.photobucket.com/albums/...psyqzzkeuj.jpg

Here is a general overview of that area:
http://i1060.photobucket.com/albums/...psxurosaql.jpg

http://i1060.photobucket.com/albums/...pscpfomh3z.jpg

Another close up:
http://i1060.photobucket.com/albums/...pscohr4uum.jpg

I'm going to try a little Meguires on the bezel area. I'm guessing it'll shine up nice.

Yeah, that does look rather sun faded, but it's not to the point that the fillers are exposed. I suppose if a guy wanted a super glossy surface, one could wet sand the entire cabinet and have it clear coated with an automotive urethane. Maybe even lacquer would work, at least with lacquer you could dissolve that off if you didn't like the looks. Ive never tried it, but I'm guessing some toner lacquer would even darken the finish.

Remember that the glossy layer in Bakelite is thin. If you get too aggressive with abrasives, it's possible to polish all the way through it, and then you are down into the pulpy under-layer which no magic potion or process will polish to a shine.

Some Bakelite cabinets will polish up nicely, and others are just too weathered (or whatever-ed). This comes up all the time in the radio collecting world. You can spray on clear coat to make a weathered cabinet shiny. Some people also use wax, but I consider that a temporary solution.

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

Thanks guys on the comments on the Bakelite. To get a real good shine on this one, it looks like I'll have to spray some clear lacquer on it and go from there. I did this on a Zenith table radio and it turned out real nice.

I replaced the door knob cap tonight. Success! I now have about 10Kv at the 2nd anode with 1 HV tester and about 13Kv with the other.

I've hooked up my pattern generator to it and I am starting to straighten out the picture.

I adjusted the ION trap for max brightness and centered the focus coil. I do have a question on the adjustment lever for the focus coil labeled Centering. I'm guessing I move the lever around to "center" the picture on the CRT. My question is there are 2 screws on each side of the Focus Coil that allows it to move up and down and from side to side. Do I loosen them to move the centering lever around and once the picture is centered I tighten those screws along with the 1 screw on the Centering lever? This is the first time I've done an Admiral and this lever is new to me.

Next problem. It seems that the H width and H lineraty adjustments do very little. There is some adjustment but the picture is past full screen. I've read the Sams on adjusting the Horizontal sweep circuit adjustments but very little happens. Is this normal? Any clue as to where to look? Remember I just replaced all the caps and resistors. I ohmed out the coils too.

Thanks.

BTW, my 210 volt line going into the fuse is now measuring 238 volts.

Width and linearity controls have a very subtle effect. The drive control will have a much bigger effect

It's playing a DVD now and it looks pretty good. I know it can be better. I'll let it play for an hour or so to "burn it in" some.

OK. Thanks. I'll let it finish playing then I might mess with it. I did notice that as I varied the 117vac input, the picture size changed too.

Today I'm going to work on the alignment. I have both Riders and Sams to go by. I'll report back on how it goes. This is pretty new to me.

Yes, that's normal. These old sets have no voltage regulation in the power supplies so things like picture size and focus will vary with the line voltage.

Thanks Bob.

Well I tried aligning the TV this afternoon and evening. Didn't go so good. Using my Eico 221 VTVM and RCA 167A signal generator, I adjusted the Video IF stages by adjusting A1 thru A4 for maximum value on the VTVM. I then adjusted A5,A6, and A7 for the sound alignment.

I then hooked up my Eico 369 and my BK 2010 O'scope. The waveform looked like this:

http://i1060.photobucket.com/albums/...psrd5droku.jpg

I then adjusted A1 thru A4 again to get his waveform:

http://i1060.photobucket.com/albums/...psd3krulul.jpg

Then I tried playing my DVD. The picture was awful and the sound was very fuzzy even after turning the "Fine Tuning" knob all the way to one end.

I went back and started all over again and made the adjustments and go the same results.

The waveform is centered on 25.MC where it should be on 24.3MC. I am getting about 8 or 9 MC bandwith on my sweep. The frequency for the waveform seems to be off all around. I used my digital freq. counter to set the frequency generator.

I did notice that the peaks and central valley seem awful narrow compared to the picture in Sams.

Any Ideas?