What is this?
 

This is the FJP I got from Hawkeye. The chassis mods for running an FJP in place of the CYP have been done, and the tube has been degaussed. WTH is this, I've never seen a pattern like this before. It's like the beams from the guns are somehow too large, causing a strange pattern on the screen. It's wierd though, I can almost actually get good convergence.

All the screen and background controls work as advertised, but all the guns will cause the same pattern to appear on the screen when advanced one at a time. Looks like tri-color chicken pox or something. Also, no amount of messing with the purity rings, blue lateral, or yoke will affect it.

Please tell me the mask is not bent...

This is making my head hurt... I have never seen anything like it before!

So you get the same color pattern with any gun turned on? or does the pattern change?

The moire' pattern produced here makes me think that the shadow mask is totally out of alignment with the phosphor dot structure, as if one of the support springs has become detached, and the entire mask structure has moved back. The fact that the repeating patterns in each color bar become larger toward the bottom of the screen suggests that the mask is perhaps tilted further from the screen at the bottom. All this is purely a WAG, as I have never seen this occur.

If you lightly tap the screen, do the colors move around? If the shadow mask was torn, you might observe a fair amount of shifting of the pattern.

jr

Mis-aligned electron guns? If the gun assembly got slightly twisted, or too close or distant, when they were reattaching the neck of the new guns to the CRT tube? I don't know what tests Hawkeye does after a rebuild, presumably more than an emission of the cathode test...

Can the metal parts of the electron gun get magnetized? Maybe a degaussing of the neck might help. :scratch2:

Would the deflection yoke being too close or distant (front to back) do this?

If it's the mask, maybe it can be coaxed into position with a magnet? But you'll need to degauss afterward.

---

What chassis mods are required to use a FJ in place of a CY? I know the anode is different but what else?

I've seen the auto degauss coil cause some weird problems but not like this, this set predates the built in degauss anyway doesn't it?

Have you tried rotating the yoke side to side, maybe the tube is in 120 deg off one direction or the other?

Have you tried removing the convergence assembly from the neck of the tube altogether?

A bent mask will usually affect one area but you will still be able to get purity in other areas, there isn't a single square inch of proper color on that screen, that makes me think it's some type of dynamic problem, like the convergence coils changing the purity as it sweeps across the screen causing that somewhat regular pattern.

If all else fails I'd give Scotty a call.

I think it looks like a message from the queen of hearts

looks like the electron guns are the wrong ones, you can see the tri color pattern but the landing is all wrong.

jr: The pattern is not exactly the same, the colored splotches move depending on which gun you turn on but the pattern is more or less the same. A red splotch becomes green, or a blue beomes red, ect. I know what you mean about the mask being out of alignment, but I've never heard of that before. I have not tried tapping the screen to see if they move, I'm hesitant because of implosion risks.

waise: Good question. The tube looks identical in every way to my CYP though, including the gun alignment. I'll try degaussing the neck tonight, though that will probably involve removing hte CRT to avoid demagnetizing anything else. I don't think it's the yoke, it seems to work as advertised.

Eric: The mods involve moving the red cathode to the same lug as green/blue, and a slight change to the chroma circuit (adding a resistor and ceramic cap to the G-Y amp). It has to do with the FJP sulphide tube having a more efficient phosphor than the CYP tube does. The literature also mentions adding a red screen control if balance cannot be achieved, but obviously I haven't been able to get that far just yet. Haven't tried removing the convergence yoke yet, I'll try tonight. I'm gonna hold off calling Scotty till I try a few things, I know he's pretty busy.

oldtvman: I know what you mean, but I trust that the tube was rebuilt correctly. Scotty did say that some of the phosphor on the screen had flaked off in a previous rebuild attempt, but it's not really noticable. With the set off, you can actually see a few spots where it's missing dots, but with it on it's not really noticeable.



Here's a question: could this be a total loss of focus? I don't really trust the focus rect in this set, and I have a spare I could try. My guess is that the screen would just be really fuzzy if that happened, and I wouldn't see much of anything at all. Just a blur.

Survey Says
 

After looking at your photos with Photoshop, I removed all of the red, green, and blue blotches. What was left was a framework of nice, crisp vertical and horizontal lines, delineating what would normally be a color bar test pattern. This, plus your previous observations, demonstrates that everything from the yoke to the AC plug is working correctly. I'm sorry to say, your problem involves the shaddow mask assembly.

Loose Shadow Mask Troubleshooting Hint
 

Here's one way to troubleshoot a shadow mask that has come loose.

Note: The chassis must be bolted in before trying this.

- Place two identical cardboard boxes, 8-10 inches tall, on the floor in front of the set.

- Tilt the set forward, resting the top-left and top-right corners of the set onto the cardboard boxes.

- Turn the set on and check to see if the displayed image has changed.

- Turn the set off.

If the display changed, the shadow mask is the culprit. If you are not sure,

- Place two additional cardboard boxes under the bottom-left and bottom-right corner of the set. The front of the CRT should now be perpendicular to the floor.

- Turn the set on and check to see if the displayed image has changed.

- Turn the set off.

If the display changed, the shadow mask is the culprit. If you are not sure,

- Remove the two cardboard boxes located under the top-left and top-right corners of the set.

- Turn the set on and check to see if the displayed image has changed.

- Turn the set off.

If the display changed, the shadow mask is the culprit.

As you can imagine, this method, as well as others, is not foolproof.

the few times we had a bad shadow mask it showed up as a purity problem, never seen a shadow mask problem like this one.

Sad to say, but everything that I have read here seems to be consistent with the shadow mask being totally out of position, not just bent or dimpled. Focus appears to be fine.

Does the box show any sign of damage? it would take a fairly severe bump to dislodge the shadow mask spring clips from the posts on the inside of the front panel. Anybody know how many clips are used in this roundie? ...3?

I suspect that the tube was fine when Scotty shipped it... I would guess that he tested red, blue and green fields to evaluate rebuild quality, and perhaps eliminate any screen contamination that might have occured during the rebuild process.

TubeTypes' test may well reveal a loose shadow mask assembly, but it is also possible that the mask could be wedged in its' present position... for sure worth a try!

sad :tears:,
jr

Considering the CRT is round... Is it possible that the shadow mast has turned like lets say 30 degrees or so? Sow now the landing is effected by the dots off kilter just a few thousanths? As the CRT cooled in the chamber, the shadow mask adhered itself again.

And this bothers me!

About a month ago I decided to invest in getting an fjp rebuilt for the future. I shipped Scotty one with a dead gun, USPS broke the safety glass on the way there, Scotty replaced it and UPS broke it on the way back.

I asked Scotty if it was possible the mask was damaged from the drops and he said the mask is super tough in those crts. So I havent even tested the tube. He said the result of a bent mask would be a rainbow

I never even tested it, its still in the box.

I feel your pain and irritation on this one! Shipping crts was one of the most annoying things I have ever attempted

Look up in the top righthand corner of the CRT pics. See the round black area thats about the 1/4 size of a quarter? Theres the issue. It's a misaligned shadow mask. Probably hit too hard in shipping like others said. The edge of the shadow mask bracket is sitting in the face of the CRT viewing area. And if you take a closer look, yes there is a bit of a focusing issue in the left hand near the middle where the white bar meets the next to the right. And the top is poorly focused where the bottom seems better.

Im sorry this happened to you. Cant trust shipping anymore I guess.

No, actually the box was perfect! I was half expecting to get a pile of crushed glass in the mail, but Hawkeye packs them very well. It was mailed with the face pointing down resting on a pile of foam, with a cardboard piece at the base of the bulb to keep it from shifting. There's basically no way for the neck to break, and I doubt it sustained any sort of shock in transit.

I'll try the box trick, but I'm not so sure I'll be able to 'nudge' the mask back into position if that is in fact what happened.

Nice try, but that's a piece of the rubber CRT bumper peeking through. :D I only intended on sticking this CRT into the cabinet long enough to verify it works, then I was gonna put the CYP back in. Guess my plans are foiled...

I have a shadow mask out of one of these ups broke and it look tough and has a low mass. It would take a super hard hit to bend/warp this thing.

Did your fjp have a safety glass on it when it arrived?

Ok, got it, but how about that right side of the CRT, it looks as if there is a shadow there at the very egde. Can you use the purity rings or H center to get that out and produce no shadow? That could be the shadow mask.

An interesting picture, if you have time to take it, would be to turn off the color bar pattern, and put up a plain white pattern.... "snow" would be fine... then turn off all but one of the guns. I suspect that the tube will still display a 3 color moire' pattern, but without the color bar information and the complexity of three source illumination, it will be easier to analyze.
jr

I'd like to see it too with a blank raster.

I don't think the alignment with the guns is nearly as critical as the alignment with the face plate, each hole is supposed to be precisely aligned with each color dot, even a small shift or rotation of the mask could screw it up badly.

Is the mask held in by anything but tension on the glass, maybe some slots it fits into?

There are 3 spring loaded tabs with holes in the end, Im assuming the holes 'lock in' to molded glass nipples to hold it in place.

I will try and take some pictures when I get home.

Thank you! I have been looking for pictures of the spring assembly...IIRC, the holes in the spring clips may actually locate to metal (kovar?) tapered posts that are fused to the inside surface of the faceplate panel...not sure, however.:scratch2:
jr

Either your tube is super heavily magnetized, or the shadow mask is damaged.
If you have the demagnetizer unplugged from the chassis, did a manual degauss, your shadow mask fell out during shipping, guess what, not repairable.
I have seen that happen many times when using UPS as shipping no matter how well tube was packaged.

If the mask is out of place, it is apparently leaning back, that is the upper part is farther away from the face (hence the smaller blobs of impurity). Unfortunately, due to geometry, if the mask moves back by some distance, the yoke and guns would have to move back about 10 or 20 times that distance to get the beam angles right for purity, and that is impossible. If the mask is totally loose, maybe you could confirm even by listening for movement after removing the tube from the chassis and rotating it face down. Sorry, but so far this all seems to indicate an unrecoverable accident.

This is the mask out of the tube UPS CRUSHED. This will give you an idea of just how hard core the mask is. Maybe the spot welds broke on one of your tabs and the mask moved back a tad.
http://justsmog.com/Clay/sm1.jpg
http://justsmog.com/Clay/sm2.jpg
http://justsmog.com/Clay/sm3.jpg
http://justsmog.com/Clay/sm4.jpg

I was looking at a photo of miniman's tube when he got it back from Scotty. Is it me, or does the gun assy look totally crooked here? or would that matter at all?

http://www.videokarma.org/attachment...0&d=1280454077

sweitzel: I don't think the gun itself is crooked, just the base.

ctc17: OMG, those bastards DESTROYED that tube! :tears:

You're right the mask looks quite sturdy, though as you have seen it's possible for UPS to ruin ANYTHING. Don't those people have standards? I mean, how is their business model viable if all they do it break stuff all the time? To answer your question, no it did not have safety glass because all rebuilds have to have the panel off in order to go through the oven. My set has a flat pane of glass anyway, I wouldn't put a bonded tube in there if I could possibly help it.

freakaftr8: I think what you are seeing is just the edge of the last color bar, I don't remember if there's another one. It's definitely not a shadow.

To all who asked: I'll take a pic with a blank raster for you. I'll cycle through each gun too, so you can see what I mean about how the pattern changes.

It's just the base that's crooked, but the optical illusion does throw me off. BTW, this is not a tube I had rebuilt, it's one Scotty sold me.

Looking at that mask the dots are arraigned in triangles like some of the splotches.

If the tabs snap on to glass posts I can see them getting broken, but then you should have stuff rattling around inside the tube.
I also wonder if it isn't sandwiched inside the two halves which would make it impossible to slid forward or back but perhaps not impossible to rotate, seems unlikely that would happen though.

If the guns were rotated exactly 120 degrees off then it should just have the colors mixed up (as happened with the French 15GP22)

Here's my $0.02:
-It could be possible that the mask deformed during the heating/evacuation cycle.
-If the tab(s) had detatched from the ring that surrounds the mask, there is likely not that much movement that would occur, and I concur that there would be something rattling around inside the envelope. Tapping the envelope would reveal microphonics. The mask looks really tough in any event.

-What about a damaged or misconfigured gun, with trajectories off or damage to the lens element structure?

It does make sense that if the mask did come loose and pull back from the screen, the beams would be larger once they actually reached the phosphor...


Good idea, I'm not as averse to shaking the tube as I am to tapping it.


colorfixer: I find it highly unlikely that the mask would deform in the oven, remember they have to bake these things when they're new as well. That and the fact the Scotty claims a very good track record on all glass tubes, according to him the onyl troubles are with metal/glass ones. I.E. 21AXP, 15G, ect. I don't think there's anything wrong with the gun either, since all the screen/grid controls work like they should.

did you say its the same with just a blank raster?

It is not a gun problem.
Even if the gun was installed improperly, you would still be able to get purity, you would not be able to converge it.
Usually the frame of the shadow mask does not dislodge from shipping, the mask part will bend and get a dimple in it when dropped. In your case, it looks like it was dropped hard enough to pop the mask frame right out of the contacts embedded in the front glass panel.

Tried the 'tipping trick' with no joy, also tried tapping the tube in different areas. Still the same result no matter what I do, which seems strange. I would have thought it would move at least a little, but it might just be jammed in there really well.

Here's pics, as promised.

First one is blank raster, brightness cranked up to see the splotches. Then I turned on the guns one at a time: first blue, then green, then red. Red is the most telling of course, you can clearly see the edge of the shadow mask off to the left. :tears:

5th photo is actually an animated GIF, so you can see the progression.

Ah well, when life hands you lemons...

At least I got a cool signature block now! :p

Who will be the first to make that their avatar?

The front is thick, over 1/2" so it could take a really hard hit and not break. Maybe even hard enough to pop the metal out and move it and not break the glass. Thats why I was asking about the safety glass because it would break long before the crt.

Did you try contacting Scotty? or is he done and gone now?

I had mine insured for $1000 and collected just about all of it.

I may go as far as to guess considering the moire pattern on the screen, not only did the mask come loose, but it way have deformed in the CRT, dimples and small creases causing the pattern you are seeing.

I have made arrangements with Scotty to drop the CRT back off at UPS, pending a damage claim- it's obvious now that the mask is off kilter. :thmbsp:

I looked through the glass, and you can clearly see it has come off one of those locating pins on the inside. It slid towards the front, even taking some of the aluminized coating with it as it went. So, it's on it's way back.

I gotta say, I know how he's been in business for this long- CUSTOMER SERVICE. Something you'll never get when you call a 1-800#, and the guy on the other end rattles off a prompt card so fast in a thick accent you don't know what hit you. He even offered to rebuild my 'dud' as an act of good faith! Not that I have a dud, I ordered this tube as a spare, my original CYP is still perfect. We'll see what happens, hopefully we can work something out.

3 cheers for Hawkeye!

BRAVO! Indeed, 3 cheers for Scotty/Hawkeye! :thmbsp:
Thanks for taking the additional pictures, it is very interesting seeing the moire' pattern with the 4 different gun illumination conditions.

Earlier, (post 2) I opined that the mask was tilted further away from the screen at the bottom. A little later, old_tv_nut (post 25) stated that the mask was "leaning back, that is the upper part is farther away from the face". Thinking more about it, I think old_tv_nuts' description was correct, and I was thinking backwards... could you verify if it is the top or the bottom of the mask that has slid closer to the screen ?

All this talk of shipping damage has me worried... today I am expecting a Celestron telescope to arrive via UPS... got my fingers crossed!
jr