What is this?

[miniman82]

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...

[jr_tech]

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

[wa2ise]

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.

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.

[andy]

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[Eric H]

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.

[oldtvman]

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

[oldtvman]

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

[miniman82]

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.

[TubeType]

Originally Posted by miniman82

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...

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.

[TubeType]

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.

[oldtvman]

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.

[jr_tech]

Originally Posted by miniman82

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.

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.

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 ,
jr

[freakaftr8]

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.

[ctc17]

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

[freakaftr8]

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.