Was wondering if you guys had any cool stories about defective CRTs, like an electron gun off-axis, ion burn, phosphor burn, overheating etc...

What would happen if the gun structure was somehow knocked off path and aimed towards the sidewall of a crt? :scratch2:

I had a Zenith once with a honest to god hole in the phosphor right in the center. No idea how that happened, either. I have a 7JP4 at home that's so wasted that the gun assembly is all blue/black from use (it's barely got a raster).

I had a Zenith once with a honest to god hole in the phosphor right in the center. No idea how that happened, either.

That happens if both horizontal and vertical deflection fails. Probably if the yoke connector fell out.

Once saw, at a hotel, a color TV crt where some sort of 1/4 inch metal strip inside the CRT in one of the corners was masking the phospors in that corner.
____________________________
Gun control is using both hands

Does having the bracket holding the deflection coil disintegrate count? It certainly makes for an odd picture.

David

I have a 10BP4 out of a Zenith that is totally worn out. The face has brownish blotches across it-I can only guess these are ion burns. I was able to get a raster after heavy rejuvination but it didn't hold.

I have a Sel-Son test crt, the type that is in a seperate box and connects with extensions cables. Sets that don't use yoke plugs need jumper wires to make the connection. Once while working on such a set I didn't have the connections tight enough so the test yoke saw no voltage. For a second (until I hit the power) the raster was concentrated in one point in the middle, and glowed orange. There is now a hole in the phosphor; crt still works fine.

My mother bought an RCA console from a freight salvage in the mid-90s. One corner had an obvious ripple in the shadow mask. I never heard her complain about it, though it always bothered me. I can't remember if I ever tried to degauss it out of there, but I don't think it would have helped.

I have noticed, mostly on DuMont built picture tubes, that the finish on the glass face will have imperfections. It is not uncommon on older color crt's to see bad phosphor dots with either a color missing or maybe a red dot where a green one should be, etc. GE seemed to be good for this.

I have a 21CY Colorama re-build in a CTC-7 with a bleep-load of bad dots. Very noticable. Also has soft focus. Wonder how many times it could have been re-built.
Kevin

Also a 12K in a Dumont RA-103 with the usual ion burn. Not that unusual, I guess.
Kevin

Maybe not the CRT itself... but a very unusual yoke. It was a homemade job, hand wound, with a shitload of little magnets and small disc caps attached to it.

It actually worked...

I remember seeing a small spot of phosphor knocked off a monochrome CRT in an early-to-mid-'60s Zenith table model. (Please don't call it a portable; it makes my groin ache like the very dickens.) The void was about the size of the head of a sewing pin, but oblate to a ratio of about 5:3--vertical to horizontal dimensions, and off the center axis by an inch or so to about a 10 o'clock position. There were rambunctious kids in the house where this set resided, and I tried to imagine perhaps a metal toy car (like those "Hot Wheels" of the time) thrown against the screen--not hard enough to crack or chip the glass, but perhaps hard enough to disrupt a tiny spot of phosphor.... :scratch2:

Also I have seen the bonded faceplate discolor, crack and craze around the perimeter of a number of color sets. I have a Zenith console up in the hayloft here that somehow managed to escape the disposal campaign my girlfriend started me doing back about 12 years ago--IIRC. I threw away about 50 large console color sets, and about a hundred table models and portables--color and b&w. All in various states of completion and repair. All accumulated over the years. All repairable, but with no market at the time--working or no, and no time on my part to fiddle with them even in fun. There were a number of the color ones that were afflicted with this sort of glass leprosy. I suppose the integral implosion protection is still for the most part there, but it still looks pretty scary just the same.

Yeah, seems like phosphor is the usual thing to get damaged. Looking back at my first post, I guess there isn't much else to get a 'defect' that would be visible since the guts of a crt aren't really visible. Lets see...anyone have some stories about a really, worn out tv that was still clinging to life? I've picked up a lot of SS tv's round here with totally cooked crt's and the chassis were still working. Also, Some sets have strong tubes when it's obvious the chassis has been through hell!

Lets see...anyone have some stories about a really, worn out tv that was still clinging to life? I've picked up a lot of SS tv's round here with totally cooked crt's and the chassis were still working. Also, Some sets have strong tubes when it's obvious the chassis has been through hell!

Let me tell you the story of the Hitachi from 1997. It was bnuilt with Zenith guts and a Zenith CRT...

It was bought brand new and it's lived in the same house since it was first brought home from the store.

Time went by... day in, day out, year in, year out. Every day it turned on and displayed the news, or whatever was on whichever channel it was set to. Eventually the corners of the picture became "fuzzy". This worsened as the dynamic convergence slowly got worse.

More years ticked by... By 2006, the picture had a greenish tint to it, was dim, and the image had bad color bleeding. Shortly after, it was retired from daily use.