Look what followed me home today! 1949-50 I think, built by Air King maybe. 12LP4A picture bulb. Knobs, HV cage, rear panel are all present, 5U4GB isn't lol

https://live.staticflickr.com/65535/51910944603_3bf6d73033_c.jpg

https://live.staticflickr.com/65535/51911467780_5edf0cb0e8_c.jpg

https://live.staticflickr.com/65535/51909881217_2ffa751ce0_c.jpg

https://live.staticflickr.com/65535/51910850081_5cb1c294ac_c.jpg

General Electric CRT ? I'll bet its still good.

What a sweet set! It was probably worth more as a 5U4 :)

Looking forward to see progress on this one.

Yep the (GE) CRT is good. I found a burned 4.7k resistor on the damper next to a sketchy looking wax paper capacitor. I may swap those and see if it will come up on dim bulbs. The dang schematic I got is the wrong one, but is similar enough that it took a while for me to figure out. Reading those pf value molded paper domino capacitors is a real pain :thumbsdn:

Very nice find. :thmbsp:

I located in Riders 5-1, as Air King models 12T1, 12T2, and 12C1, chassis 700. Your Silvertone version is way out in Riders 10-1, and they show the exact same schematic as the earlier Air King (drawing number 5958). Seems like the Sears chassis no. 110.700 even corresponds to the Air King chassis 700. It appears they used that same chassis with slight modifications with every CRT size under the sun, including rectangular ones. Oh and you probably know it's basically the same Air King chassis in Sams 121 folder 3.

I couldn't find it in Rider's :scratch2: There's a burned resistor on pin 3 of the damper (6W4GT) the (wrong) schematic doesn't show any resistor on pin 3.....

Very nice find. :thmbsp:

I located in Riders 5-1, as Air King models 12T1, 12T2, and 12C1, chassis 700. Your Silvertone version is way out in Riders 10-1, and they show the exact same schematic as the earlier Air King (drawing number 5958). Seems like the Sears chassis no. 110.700 even corresponds to the Air King chassis 700. It appears they used that same chassis with slight modifications with every CRT size under the sun, including rectangular ones. Oh and you probably know it's basically the same Air King chassis in Sams 121 folder 3.

I might have a physical copy of the Sam's folder for this TV in my Sam's Photofact Stash that I could upload or email to the OP. :scratch2:

I couldn't find it in Rider's :scratch2: There's a burned resistor on pin 3 of the damper (6W4GT) the (wrong) schematic doesn't show any resistor on pin 3.....

Here's a couple pictures from Riders. Unfortunately I have no way to scan these large pages but these pictures turned out quite clear. If you left click on you can zoom in.

https://live.staticflickr.com/65535/51913910161_98be7ab96d_k.jpg

https://live.staticflickr.com/65535/51914228814_bc2c168bef_k.jpg

I might have a physical copy of the Sam's folder for this TV in my Sam's Photofact Stash that I could upload or email to the OP. :scratch2:

I'm sure that would help with the visual orientation when locating components. :yes:

Awesome! Thanks! Looks like it’s a 47k resistor that cooked

Brought it up on dim bulbs. sound works, horizontal runs....drew a teensy weensy arc off the HV anode (at the jug), not enough for a raster. I think this set runs in the 10-12KV range, and that should draw a decent arc. The B+ is low I think. I may just go ahead and get new caps

I might have a physical copy of the Sam's folder for this TV in my Sam's Photofact Stash that I could upload or email to the OP. :scratch2:

That would be great if it's not too much of an inconvenience :thmbsp:

That would be great if it's not too much of an inconvenience :thmbsp:

I believe I found the Sam's for your TV in my Sam's Stash.


See Picture Below.

I believe I found the Sam's for your TV in my Sam's Stash.


See Picture Below.

I'm not seeing that as a match, other than it's a Silvertone. ;)

I'm not seeing that as a match, other than it's a Silvertone. ;)

Yeah I realized that after I posted it...:sigh:

Back on the subject of HV. I can draw a decent arc on the output of the flyback, but after the HV rectifier I can barely get anything. HV rectifier is good. Could the 500 pf 15kv doorknob capacitor be leaky and pulling the HV down? Or should I just stop being lazy/cheap and recap the horizontal section?

I had similar symptoms on an Emerson the other day and it was indeed a leaky doorknob capacitor.

I noticed the HV rectifier filaments are not lighting up. I tested the resistance of the secondary "winding" for the HV rectifier and its fine (0 ohms). The HV rectifier works fine in a different TV. So the filaments for the HV rectifier are getting no power. I can still draw a healthy arc off the flyback output.

I'll look to see if there's anything goofy with the flyback's core where the rectifier filament winding is.......

Check and see if the filaments light with the plate cap disconnected.

Tried that, Nope.

Try getting rid of the doorknobby. If the CRT has a decent enough aquadag coating it may not need it.

Took the doorknob out of circuit, still no filaments

I'm curious. How can you tell if the HV rectifier filament is glowing or not? These tubes almost always have 1- to 3-volt filaments (typically 1B3 in b&w TVs, 3A3 in color sets), so there is ordinarily no way to tell if the filament is glowing. (In other tubes with 6-volt filaments, for example, the filament will light with an orange glow if the tube is working as it should.) I would also think if there is any kind of visible glow in a tube with a 1-volt filament, there would be a problem somewhere in the filament supply and the tube, of course, would not operate nearly as well as it should, if it works at all. If the TV produces a bright picture with no distortion, the HV rectifier is working, whether or not the filament appears to be glowing.

Edit: I just read one of your other posts and read you had tried the tube in another set; as you stated, the tube worked well. This eliminates (or at least should eliminate) the tube itself as a possible cause of the trouble you describe. If the problem persists even after replacing the doorknob capacitor in the HV cage, it is almost certainly somewhere else in the HV supply, possibly the flyback. I don't remember that much about how flyback HV systems in televisions are supposed to operate (I had to give up my workshop over 20 years ago when I moved to an apartment, so haven't seen the innards of a TV set since then, except in photos here on VK) so this is about the best I can do.

I truly hate to tell you the flyback may be bad, but since you seem to have tried everything else, this is almost certainly the last thing that could be causing your problem.

Are you certain that the horizontal oscillator is operating and running reasonably close to the correct frequency?

Do you have an oscilloscope?

jr

The HV rectifier works fine in a different TV.
Are you able to see its filament lit when it is in that other TV set? As Jeffhs mentioned, sometimes it is hard to see the filament glow from a 1B3GT or other HV rectifier tube.

In a darkened room, the filament should be visibly glowing dull orange. That is, assuming you have a clear visual up inside the anode.

Are you still running it with all those old paper caps in it?
if so you you are lucky you are getting it to do anything at all! :O

Mostly original caps. Hv rectifier is 1X2B. I wanted to see if I could get a raster before doing a recap job. And I’m pretty sure the horizontal is running……

Is that an “air arc” , or is the nut driver grounded? :scratch2:

jr

Grounded, should I get a good air arc if the horizontal is happy? I get a teensy air arc now……

Perhaps the horizontal too weak to make enough juice for the rectifier filament and it’s just time to recap

Grounded, should I get a good air arc if the horizontal is happy? I get a teensy air arc now…
You should get a healthy air arc of at least a quarter inch or more. Grounded?!Yikes!!:eek::yikes::no:

One of the things I keep around is an old defective compact fluorescent lamp. They are getting harder to find with the shift to LED bulbs.
The gas inside can be ionized, and the bulb lights, by the high frequency electromagnetic field from the H output tube or flyback.
In the past the trick was done using a neon bulb but the fluorescent is more spectacular.

“teensy” sounds a little small... do you get a larger air arc at the 1X2 plate cap?

jr

Yeah the arc is really small at the plate cap, I also suspect the B+ is too low as well, Recap and new power supply resistors soon

Got to back to playing with this this afternoon and I got a picture and sound. Tacked in some fresh(er) filter caps from the junk box, replaced the 25uf electrolytic that was across the horizontal centering pot (C50 in the schematic), and twiddled the knobs until I got a picture. Let's do the full recap now :banana:

Very nice find. :thmbsp:

I located in Riders 5-1, as Air King models 12T1, 12T2, and 12C1, chassis 700. Your Silvertone version is way out in Riders 10-1, and they show the exact same schematic as the earlier Air King (drawing number 5958). Seems like the Sears chassis no. 110.700 even corresponds to the Air King chassis 700. It appears they used that same chassis with slight modifications with every CRT size under the sun, including rectangular ones. Oh and you probably know it's basically the same Air King chassis in Sams 121 folder 3.
Some Sears sets seemed to be regional. We never saw too many Sears sets built on the east coast or the west coast.
Most of the sets sold in the stores in the mid-west were built by Arvin or Warwick, with a few Stewart Warners thrown in!
There must've been some bad blood between Well Gardner and the Sears buyer, as I never saw a Sears set built by them.

Wasn't Air King based out of Brooklyn NY?

Anyways I just ordered the bulk of the replacement capacitors for this set. Do the 24pf 3000v capacitors in the horizontal section need to be mica types? Multilayer ceramics exi$t but are on backorder.......

The bulk of the recap is done, plus I swapped out that sand resistor. The horizontal isn't completely happy, The HOT is flaky, the horizontal centering pot doesn't do much til you reach one side. Something is clamping the vertical, it folds over if I crank the height up, it never fills the screen. I played with the EM focus ring, got it to where the deflection isn't cut off like in previous pictures......not sure where it goes exactly or how you set that up. I verified that my source content isn't 16:9 (sure looks like it lol)

Update: got vertical, can stretch to fill phosphor if needed, wrong value resistor was to blame. I have too much horizontal with weird fold over and some retrace lines.

That looks to me like both sides of the picture are there but the horizontal output is not transitioning to the damper in a linear fashion. Have you tried another horizontal output and damper? What happens when you adjust the Horizontal Drive control?

I tried swapping the HOT + damper and it's the same. Horizontal Drive doesn't do anything.

Horizontal width doesn't do anything either FYI. those 24pf 3000v capacitors in series going between the fly and pin 5 on the HOT are original and one of the few things in the horizontal circuit I haven't checked......

Edit: Schematic calls for a 6BQ6 HOT, I have a 6DQ6 in there. Could this cause my problem?

Horizontal width doesn't do anything either FYI. those 24pf 3000v capacitors in series going between the fly and pin 5 on the HOT are original and one of the few things in the horizontal circuit I haven't checked......

Edit: Schematic calls for a 6BQ6 HOT, I have a 6DQ6 in there. Could this cause my problem?

6DQ6 is listed as a good sub, but never hurts to try what they originally used.

I swapped in a good Sylvania 6bq6gtb and a tung sol 6w4 damper and I have a better picture, the drive line isn’t as bad but pic is wavy and stretched to the left of it. Horizontal drive, width, and linearity do nothing still. I may take a break from the sweep and see why sound doesn’t work. It quit sometime during recap

Well we have a sudden shrink of picture for some reason. Horizontal lock is shaky. I checked for HV arcing, none of that. Changes the 1 Meg resistor on the hv anode, swapped in some other horizontal oscillator and sync separator tubes in for good measure. This guy is getting ready to get mothballed again:sigh:

That keystoning makes me wonder if the yoke failed, a cap in the yoke shorted, or the vertical is leaking into the horizontal circuit elsewhere.

Well we have a sudden shrink of picture for some reason. Horizontal lock is shaky. I checked for HV arcing, none of that. Changes the 1 Meg resistor on the hv anode, swapped in some other horizontal oscillator and sync separator tubes in for good measure. This guy is getting ready to get mothballed again:sigh:

It looks like the yoke failed when you were working on it! Not totally unheard of, when waking up a set that wasn't used for at least 60 years.
A 52 degree yoke. I have one from a scrap Admiral that should work! :scratch2:

Thanks guys for the guidance (and possible replacement yoke):thmbsp:

I looked at the yoke, checked the resistors on the vertical windings, high but not crazy, and the capacitor I replaced on the horizontal windings was a 47pf and I read it wrong and replaced it with a 470pf. D’oh! Put a crusty 47pf ceramic disc on and now have normal-ish deflection. That stupid drive line is still there but not as bad and the width is still uncontrollable but we’re doing a lot better!

Excuse the blanking in the photo and crooked yoke

Back to beating this dead horse. I got the sound back after messing with the 4.5mc coils. The horizontal circuit still isn't completely happy, kinda stretched on the left side and the width control still doesn't work. The horizontal drive line can be mostly adjusted out. The yoke may still be suspect, but there's two 24pf 3kv capacitors in series (makes them 12pf at 6kv?) that couple the oscillator to the yoke/damper that I haven't changed yet due to finding suitable replacements. So close.........

I found a thread about horizontal drive lines and Barkhausen interference. I may play with this set over the weekend.....

http://www.videokarma.org/archive/index.php/t-266745.html

Drive line has been eliminated! I took C64 out of the circuit completely (.05uf capacitor between the cathode and one of the grids of the horizontal output tube)

The horizontal width (L10) and Horizontal linearity (L9) coils still don't do anything when adjusted. I know the slug in the linearity coil moves with the adjuster screw, and I think it does with the width :scratch2:

I have a good solid bright contrast-y picture otherwise, focus is kinda poor at the sides. I have played with the position of the focus coil/electromagnet to get things centered I guess.

I think I have this dialed in close enough. The horizontal width slug is cranked out quite a bit and I hooked the doorknob cap back up and was able to shrink the width of the raster to where its not spilling over too much. I have been playing with the focus coil (electromagnet?) position to get the best centering/sharpness, focus is cranked all the way up and we're kinda soft on the edges.

We'll call this mostly done as it is watchable and nothing seems to be smoking/burning/red plating.....

I think I have this dialed in close enough. The horizontal width slug is cranked out quite a bit and I hooked the doorknob cap back up and was able to shrink the width of the raster to where its not spilling over too much. I have been playing with the focus coil (electromagnet?) position to get the best centering/sharpness, focus is cranked all the way up and we're kinda soft on the edges.

We'll call this mostly done as it is watchable and nothing seems to be smoking/burning/red plating.....

Looks good!

Thanks. I tweaked it a bit got a little better picture, and obviously it looks better in real life :thmbsp: