showing off my TV

[Charlie]

When I find that I have multiples of the same schematic, I just send out the extra copy instead of scanning a copy.

The photo on the front is different from yours because they used the same chassis in many different cabinet styles.

If your blow on any parts to cool them down and it makes a difference on the picture, that's a good sign the part needs changing.

I returned today from Dallas... was picking up my 2nd 21FBP22 that they previously tried rebuilding, but had to do it again because they found the gun to have a short. I had inquired about the dag paint, and he told me next time I come up to bring a milk jug and he'd fill it up for me. They buy it in drums I think. He was not sure where to get it in smaller quantities. Now days, they use a water-based paint (used to use laquer years ago). I'm not sure where to buy it, but they mentioned trying a paint shop... said that the paint is pretty simple stuff.

Anyone else got any ideas on where to get the paint?

[Eric H]

Charlie, check the early color forum, I posted a link to two 21" tubes, possibly rebuildable duds, and they are in Texas!

[jshorva65]

MIKE: The Aquadag can be recoated using G-C Electronics part# 10-4807 conductive paint. It comes in a 12-ounce spray can available for about $27 through ACK Radio in Georgia and marketed as an EMI/RFI shielding product. Before recoating, you'll need to remove the tube from the cabinet, remove the yoke from it, clean the tube surfaces with denatured alcohol, and mask it. Discharge the dag capacitance before handling the tube. Use great care to not drop, strike or scratch the tube during any part of the handling of it. The glass construction and high vacuum make for a spectacular and dangerous implosion if the glass envelope breaks since the tube surfaces are actually supporting tremendous atmospheric pressure. The faceplate alone is under more than two tons of pressure from the atmosphere. Set up a "paint booth" in a garage by obtaining an old large-appliance box and cutting it to leave the bottom and three full sides which will define an area where you can leave the tube unattended overnight to dry without it being damaged. The booth will also stop any overspray from getting on floors, walls, etc. Mask the faceplate of the tube with a sheet of plastic and tape the plastic to the tube with a continuous strip of tape that lines up exactly with the edge of the original dag border around the funnel-to-faceplate seal. Set the tube face-down on a thick, soft surface like an old blanket folded into about a 30" x 22" rectangle. Next, wrap plastic around the tube neck all the way up and secure the wrap with electrical tape. Run tape around where the original dag ends to mask exactly along the original border adjacent to the neck. You'll also see a big, circular void in the dag coating at least 4" in diameter (usually close to 6" on those 24" tubes) around the anode connector. Thoroughly clean the glass (again) around the anode connector with denatured alcohol to remove all the carbon trails. Inspect this area with a magnifier if necessary. This will be the most critical region of the tube surface since it's directly adjacent to the anode connector and about 15kV. Mask this circular area with electrical tape, again taking care to follow the original factory border. The clearances are critical and usually specified in the original design drawings of the tube with a tolerance (+/-1/8" to +/-1/4" typically). Verify an ambient temperature between 60-80 degrees Fahrenheit as that's the optimum range for application of the paint. Shake the dag spray for at least a full minute to make sure it's thoroughly mixed. Spray from a distance of 8" to 12" from the glass and keep the spray moving to form a nice, uniform, thin coat. Turn the tube around by rotating the blanket it's resting on if you're having trouble getting to the opposite side of the tube. Once you've got a nice, even first coat, let that dry for 1/2 hour to 1 hour. Spray another thin, uniform coat and let dry. Use a third coat if desired. Turn the "booth" around with the open side against a wall and mark the box "CAUTION, KEEP AWAY", "WET PAINT", etc. Let dry overnight. Again, handle the tube with great care. The structure is very strong to support all that pressure, but tripping over a crack in a driveway while carrying it and dropping the tube will almost certainly shatter it. In my "young and crazy" years, we took "dud" picture tubes into a large, open field on the few extra acres of land my grandparents owned behind the family business where we did our target practice and shot these 12" to 24" tubes with high-powered rifles and shotguns from about 50 yards away. The noise was about equivalent to 1/4 to 1/2 stick of dynamite. It wasn't unusual for the implosion of a 21" tube to hurl palm-sized chunks of glass 20-30 yards from "ground zero" and displace loose dirt leaving a "crater" under the spot where the tube was sitting. Afterward, we vacuumed the area with a miniature version of a street sweeper that was normally used to sweep 6 large driveways and a parking lot on the front few acres. Basically, it was a cross between a lawn tractor and a vacuum cleaner. As I remember, there was quite a mess to be cleaned up after an afternoon of tube-shooting. I've never seen a tube "blow" in a repair shop, but I heard about an incident when a not-too-sharp tech made the mistake of cutting the tension band off of a 25" tube to remove its mounting lugs. Apparently, he heard the glass start to crack just in time to get safely out of the room before it "blew" and found chunks of glass embedded in the walls after the blast. From the oldtimers' telling of that story, it seemed amazing that no one was seriously hurt or killed.

I just re-dagged a 10BP4 for a customer who bought it from an eBay seller who had wrapped it in adhesive-backed bubble wrap which was placed with adhesive directly against the dag. I recommend wrapping CRT's for shipment using an inner layer of non-adhesive bubble wrap and then it's ok to use the adhesive-backed stuff as outer wrap so it won't touch the dag.

JSTOUT: I'm also 38. My son, age 14, will be recapping his first tube radio soon. Tim has been playing guitar for a few years and has a strong preference for tube tone. He's been helping in the shop, mostly on lift-and-carry tasks that require two people like unboxing 630TS cabinet/chassis assemblies to get them ready for "pulling" the chassis for recapping.

I've been "technically curious" since childhood. I've traced everything back to the explosion of the plug of a defective box fan in my hand at age three. Tim's experience is similar, having turned on a large guitar amp while using it to support himself as he was learning to walk and then run screaming out of the room when bumping it caused the reverb springs to bang together and the amp to emit a loud bang and ear-splitting howl. To this day, he remembers that incident.

[bgadow]

How far will a can of that paint go? (how many crt's?) I have 3 or 4 in need of recoating. I work with all manner of automotive paints every day but know of nothing that fits this description; I've thought about trying to mix together some charcoal dust with paint to make a brush-on coating. 3M makes a powder we use which consists of limestone, activated charcoal & carbon black-I wonder, if mixed with a binder of some sort, if this would be workable?

[jshorva65]

I'm not sure at this point about what its coverage is, but my best guess is that its square-inch coverage would be consistent with a similarly-szed can of ordinary spray paint. Since the surface area of the dag coating on a 1940's tube such as 10BP4 and that of larger 1960's tubes like 24MP4 are widely different, I would not be able to predict results that closely. A rough approximation of the coverage of a can of paint less a reasonable estimate of overspray divided by a rough approximation of the dag surface area of an average CRT divided by two coats would be the setup for the calculation.

N= number of tubes
A = total coverage (square inches)
L = overspray loss (percent)
T = average CRT dag surface area (square inches)

N = A*(100%-L)/2T

[dewickt]

A can of spray dag should do at least 6 medium size tubes.
The story about the tech cutting the shrink band to remove the ears to make the tube fit a different mount is TRUE, I herd it happen, sounded like a shotgun blast, he had console on it's face and was lowering tube into it, tapped the tube on the floor when it was fully in - BOOM - was a miricle that the did not get cut as he was leaning over the cabinet when it blew. This was done by at part time used TV shop at a local inside flea market, he was only open on weekends. Nick named "Brand X" he closed up shop the next week, learned his lesson the hard way.

[Charlie]

Originally posted by jshorva65
Basically, it was a cross between a lawn tractor and a vacuum cleaner.

Trying to invision The Kubota Dirt Devil

[jshorva65]

The story about the tech cutting the shrink band to remove the ears to make the tube fit a different mount is TRUE, I herd it happen, sounded like a shotgun blast,

That makes TWO such incidents, as the one I heard about had happened in a local shop and the walls still had the gouges where the glass had dug in. I worked there for about a year between college and my first contract engineering job.

Our local newspaper had a story in News Briefs headlined "Texas Woman Killed By Exploding Television" during the first week of July, 1986. The story, as I remember it, was that a violent domestic incident between a husband and wife involved the throwing of a television set. Later, the wife's sister came over to help her clean up the mess. She picked the TV up off the floor and BOOM! She died about an hour later at an area hospital of blood loss from massive cuts to the face and neck.

[jshorva65]

Originally posted by Charlie
Trying to invision The Kubota Dirt Devil

More precisely, it looked something like an oversized golf cart with a vertical-axis rotating brush on each side and a wide horizontal-axis brush underneath. The vacuum system caught whatever the brooms kicked up and deposited the debris in a big black plastic container at the rear of the machine. The controls included a steering wheel, throttle and brake pedals, FWD-N-REV automatic transaxle selector lever and electric start. There were also levers labeled BROOM CLUTCH and VAC CLUTCH. I vaguely remember its engine being 2-cylinder air-cooled 4-stroke. Based on my limited small-engine experience, it was probably 16-20 HP ... probably an 18 HP Wisconsin or similar. Usually, it was parked in a pole building behind my uncle's place next door. It also came in handy back behind Uncle Mike's picnic pavilion and swimming pool around the 4th of July ... lots of spent fireworks shells to sweep up after the annual bash. I guess the term "upper middle-class rednecks" sort of fits my background. Most everyone either worked at or was retired from some sort of manufacturing job or owned a small business. Back in the 70's, we had access to some pretty impressive fireworks, too, thanks to a few independent "owner/operator" truck drivers among us who drove over-the-road across the "lower 48" states. The "half sticks" they'd bring back from a run would blow a 2- to 3-foot diameter crater in loose dirt.

[mbates14]

here is the problem charlie.

Which part. Thats the question.

I would start to freeze spray the seleniums, and the resistors, BUT I dont have any local suppliers.

[mbates14]

I would like to build a tube AM transmitter. I been googling all over, but i want a simple, easy to use schematic.

I have some tubes, and a 700VDC power transformer being waisted.

an 807 is just collecting dust also. I would like to build a good transmitter, about 100mw or so. 100mw being the legal limit.

(another off topic thing, as im great for doing that )

The reason I ask, is because I have a couple tube radios, one being a turntable, and one being a portable DC tube radio. (7 9v batteries btw).

I had a SS transmitter, but i think they sound like sh*t and I like tube better anyway.

Speaking of methods of cooling stuff off for testing porpoises:

Back in the days of carburetors and cheap Freon we'd cool off the choke with a blast of R12 so that it could be set properly.

Sometimes a entire can of Freon would get used up to make sure the choke was working properly (cool off, start engine, check operation, repeat).

That's my personal contribution to the hole in the ozone. You're all quite welcome. Ahhh, blissful ignorance, those were the days!

Anthony

[mbates14]

Charlie, pull out your copy of my TV schematic.

please correct me if im wrong, which i might be, but after intense studing of my vertical section, and that schematic I have drawn some conclusions:

My vertical linerity is sorta bad, and the vertical will shrink after it runs for a little bit. its a slow shrink, kinda like a sunset.

so, It cant be before the vert output tube 6s4, because it would start to roll, or loose sync. The picture stays locked completely.

it HAS to be the output. I did notice that the vertical linarity control is run through the cathode of the output tube 6s4.

well also, if you look there is a little paper wrapped electrolytic 50uf, comming off the same cathode to ground, I got my eyes on that cap.

well, here is where i may be wrong, but there are (2)2.2meg resistors in that circuit, one providing volts to the grid, and another comming off the grid back to ground.

well, that cap could be dried up, and run the bias off, because i think that paper 'lytic works the bias on that tube, (this is where you need your copy). well, to the point:

i think that lytic is dried, so it could throw the bias off, and make the tube run a little hot, and then that would be the source of my linarity problem, because the linarity is controlled through the cathode, and that cap could be gone, throwing off the cathode bias, (hence) the linarity is off.

This is causing the tube to run amped up, and then the 2.2meg resistors are overheating, dropping the volts on my grid causing low output, hence insufficiant vertical deflection. (this is where you correct me if im wrong via schematic ).

I have come up with these conclusions by studying the schematic.

Any opinions, or facts would be considered, im just studing to find out possible problems, and required solutions (replace lytic cap). no ESR meter, too expensive.

Another conclusion I considered, would be the cap breaking down under load, lowering the tubes output.

[Charlie]

Mike,

The first thing I would try changing is lytic C2-B on the cathode of the verticle output tube. It has been my experience that this is usually the culprit for most of my verticle shrink problems... especially in color sets. Just for shits & grins, change C62 and C63 as well. While working in this area, check those resistors you mentioned to verify they are within tolerence.

if you look there is a little paper wrapped electrolytic 50uf, comming off the same cathode to ground, I got my eyes on that cap.

Note: According to the number you gave me the other day, your TV has chassis 528.38503. The diagram shows C2-B as being 50 mfd. But... notice on page 14 in the capacitor parts list... there is a note by C2-B. It says that your chassis should use 100 mfd instead of 50 mfd. Just wanted to make sure you caught that. When you follow the circuit in your set, double check this to make sure.

IMO, you should just go ahead and change as many of those caps in your set as you can get. It looks like your set uses those paper-wax and plastic tubular caps for couplers, and those are always prone to failure after 50 years. Same goes for your electrolytics. You'll find that in most cases this will pretty much correct almost all of your set's quirks, and also it will save you time in the long-run. I'm sure that most everyone here will agree with that.

[Chad Hauris]

You don't want to use an 807 for a part 15 unlicensed transmitter...that is a 25 watt tube at least. The FCC will be calling.
Check out Robert Casey wa2ise's web site for info about tube AM micro-transmitters. You can use parts from an old AM tube type radio.