[Eric van Ballegoie]

The old blue tube on my Sony 1270QM was far gone and I've recently bought a used blue tube from projectorspecs (in very good shape!) and I plan to swap the tubes next week.


The tube which I got from projectorspecs came mounted with everyting on it (DY, Sub DY and magnets) but I have some questions about it.


The picture below show a photo of the 2/4 pole magnets which are currently mounted on the new tube:

http://www.dvdzone.nl/kijkruimte/new-tube.jpg


I've got the service manual for this projector, and from what I understand, the left most ring in the foto (the one without the 'screw') is the 4-pole magnet and the middle one the 2-pole. But I'm not sure what the third (right-most) ring is for?

QUESTION 1: Any one know what this right-most ring does?


The service manual futher states that turing the 'screws' modulates the power of the magnetic force, while turning the ring will adjust the direction of the force. I understand how to set the direction, but I'm unsure how I know how to set the power of the magnetic force.

QUESTION 2: How do I know how I must set the power of the magnetic force?



On another note: The tubes which are currently in my projector have a different type of 2/4 pole magnets. In the picture below you can see what I mean:

http://www.dvdzone.nl/kijkruimte/old-tube.jpg

QUESTION 3: How do these 2/4 pole magnets work, and which levers set the power of the magnetic force, and which ones the direction?


Any help would be greatly appreciated, so thanks in advance for your help!


Eric

 

[Mark Glover]

Hey Eric,


Good pictures.


The top picture is a tube that looks like it came out of a 1251/2 or 1271/2 while the second picture is the tube from a 1270.


The rings closest to the yoke are the 4 pole set and the rings toward the back are the two pole. The paint on them holds two rings together. Break the paint seal with an exacto knife and use the tabs to rotate them to achieve the intended adjustment according to the manual.


The 4 pole centers the dot and the 2 pole shapes the dot.


Sorry but I dont know what is meant by "power of the magnetic force"

 

[deronmoped]

That new tube looks just like my 1272.


The way I adjusted the magnets was to get a 6" piece of tubbing that fit snugly over the adjustment knobs so I could look into the tube while adjusting them. I put on a pair of sunglasses and put up the H pattern for that screen. Set the electric focus as best as I could and then went back and forth between the two knobs to get the best focus on the H pattern. Then I checked the electric focus again. After you do this a few times you will find the sweet spot for each knob. I didnt bother to defocus the blue tube. That was because in the best focus I could get it was not as sharp as the green or red.


Doing it this way was easier for me to see the results of focusing then going with the dot pattern.


Deron

 

[Eric van Ballegoie]

Hi,


Thank you both for your answers!


I'm still a bit puzzled about the three rings on the new tube.


As I understand the ring on the left (which does not have a knob in my case) is the 4 pole, and the other two together are the 2 pole magnets. Is that correct?


thanks again for the help.

 

[deronmoped]

If you can find it in the CRT archives there are some pictures and an explanation of just the question you are asking.


Deron

 

[Mark Glover]

According to the service manual those two rings with the knobs are the 2 pole magnets. One knob probably works the horizontal shape of the dot while the other works the vertical shape to give a better shape than the single slip ring magnets on the earlier 1270 tubes.


Good tip Deron on using the plastic tube extension.

 

[Simon J]

I'm also a little bit confused about this, if I look in the manual it looks like the one on your picture without the knob is the 4-pole magnet and the one in the middle is the 2-pole magnet but I don't know what the one most to right is???

Do the 2-pole magnet consist of 2 magnets/rings??



//Simon

 

[Eric van Ballegoie]

I've tried a seach of the forum, but I'm still pretty much in dark on my questions 2 and 3.... Any light on this (maybe Curt of Chuck??) would be highly appreciated as I plan to replace the tube tomorrow.


One additional question:


The 'new' tube has a different 2/4 pole magnets system compared to the old one (clearly shown in the pictures). Can I just put the new one in my 1270, even though it has a different kind of 2/4 pole system as the other tubes?


Thanks again!

 

[Curt Palme]

Why not just move the rings from the 1270 onto the new tube?


Email me your fax # to:

[email protected]


and I can fax you the 3 pages from the Sony manual.


Curt

 

[Eric van Ballegoie]

I've succesfully installed the new tube which seems to work just fine, thanks for the help!

I've correctly set the G2 level (with AKB off) and the alignment was OK on the new tube.


I was told by somebody on a Dutch forum that you need the check the gain and cut off values of the tube with a scope, it that correct? He wasn't sure if this applied for Barco of Sony projectors. The service manual doens't seem to mention the need for a scope anywhere.


Eric

 

[Guy Kuo]

The third, most anterior ring is either non-functional or a 6 pole correction. The rearmost is the 2 pole and the middle is the 4 pole. These are used for astigmation adjustments.


I assume you know how to change the beam focus and don't get that confused with lense focusing.


The 2 Pole centers the electron beam in the electron beam lens. Adjust this while displaying either a dot pattern or a center cross. Intentionally overfocus the electron beam making the image one which has a central, bright "core" surrounded by a flare. (Underfocusing makes it a fairly uniform blur without a brighter core). Turning the small knob alters the amount of deflection. Spinning the knob around the axis of the tube neck changes the direction of deflection. Between altering amount and direction you can make the central bright core centered in the flare.


The 4 Pole alters the ovalness (single axis astigmation) of the electron beam lens. Adjust this while displaying a dot pattern which is underfocused (a uniform blob rather than bright core and flare). Twisting the little knob alters the amount of elongation or shortening. Spinning the knob about the tube axis changes the axis of the elongation. Make the blob as circular as possible in the center of the screen.


The 6 Pole adjustment is also done with the dots pattern in underfocus. If the 6 pole works (it may not do anything) it creates a triangular astigmation change. Use it to correct any residual triangularity which you could not correct using the 4 pole.


You'll have to go back and forth between the 2 and 4 pole adjustments to get things right. As a final check, carefully watch the dots as you go from under to overfocused. The dots should stay almost motionless as you vary the beam focus.


The old tube has the same magnets except they are without the convenient little knob to turn and supplied as pairs of tabbed rings. The tab ring pairs from rear to front are again 2, 4, 6 pole (6 pole isn't always present). To get the same effect as turning the little knobs you spin the two rings of each par in opposite directions. To get the effect of spinning the little knob around the tube axis, you simply spin both rings together. The little know arrangement makes things easier to do in fine increments. It takes a deft touch to work with the tab rings.


You will have to redo raster centering after using the CPC magnets. If this is the blue gun, you'll probably want to leave the electron gun underfocused enough to make its light output measure about 20% higher than its fully focused state to improve grayscale tracking at higher light output.

 

[areno]

I will be setting up my 1252 next week and had the same questions that were discussed in this thread. Guy's explanation of the arrangement "The tab ring pairs from rear to front are again 2, 4, 6 pole (6 pole isn't always present). " seems to fit what was in the initial jpg pictures since I would assume that the 6 pole doesn't have a turn screw since it isn't used. This however, is different than the picture on page 208 of the setup manual. The manual shows, from back to front, an unlabeled 6 pole, the 2 pole and then the 4 pole. I just want to hear one more time that the manual is wrong before I attemt to make my adjustments. It makes sense that it is wrong after looking a the jpg pictures at the top of the thread and hearing Guy's expalanation but just wanted to hear someone say it. Thanks, Adam


I don't know what I would do without this forum.