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[BRAND SPECIFIC][ZENITH]

IQB64W10W & IQB56W10G
Servicing Methods and Tweaks

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Tip from Lenny Zimmermann: "First off let me state that I give no warranty, express or implied, that any of these procedures will do anything to your set other than screw it up. In fact some of these adjustments may be considered procedures that should only be performed by a qualified technician as you may be working near circuit boards and power supplies with high voltages passing through them. The dangers may not be extremely high if you are careful, but they exist never the less and can be quite harmful or even deadly.  Many of these procedures may void your warranty on the set. So please take caution with these procedures and know that I cannot take any responsibility for what you do with this information. All of these adjustments should only be performed by a qualified technician.

With that said some of these procedures can bring about a much better picture and greater enjoyment of your set, if you are willing to ignore the warning above. Thankfully Zenith was kind enough to position everything so that they are accessible from the front of the set so you will not need to remove the back of the set for any of these procedures. Also the screen will be right in front of you the whole time (so there is no need for a partner with a mirror.) I would recommend, however, that you have a printout of the Zenith Service Menu Codes and make note of any service menu items you have that differ from the defaults and what those are set at on your set. You may also wish to make some kind of physical marking on anything you will be moving around, such as the electronic focus or screen trimpots, by using a crayon, grease pen, paint, etc. In this way you can set everything back to where it was should you run into problems or find that your tweaks have made things worse.

I am NOT a television expert by any means of the word and this is simply information I have gathered from the Zenith service manual for these sets as well as from several message boards, the internet and, of course, this web site. I have done some of these procedures to good effect, while a very few others I have not performed on my set.

It is quite possible, perhaps even probable, that some of my interpretations of service menu items or procedures are incorrect. For those who do know what the correct interpretation would be I would be eternally grateful if you would contact me at zarlor@acm.org so that I may provide the correct advice to the many others who are trying to tweak their sets with these instructions.

I’d also like to say that some of the procedures listed state that they are normally performed with specific equipment and, as such, I generally did not detail those procedures. They can be found in the service manual for the set should you have access to some of that equipment and wish to know more details. And now on with servicing methods and tweaks.

Always make sure the set has been operating continuously for 30 minutes before making any changes to the set. Zenith recommends that the set never be operated for more than 10 minutes at a time with a still image (which a crosshatch or dot pattern grid are) to prevent CRT etching, or burn-in.  It may be acceptable to go for longer periods with the contrast turned down, but generally there should be no need to risk it.

Zenith recommends that any of these adjustments be done in the order presented.

For reference the Service Menu is accessed by holding the <Menu> button on the remote until the on-screen menu disappears, then let go of <Menu> and press, in order, <9>, <8>, <7>, <6>, <Enter>.  Menu items are selected by pressing the up and down arrows on the remote and the value may be changed by pressing the left and right arrows. The Mute button may be used to change which mode a setting affects if it has multiple modes [such a R-Drive can have settings for W(arm), M(edium) or C(ool)]. Pressing <enter> will save your changes and exit the service menu. This will often cause the screen to turn green and static-filled. This is NOT a problem! Simply change your input mode (by pressing <Video>, for example) and it will clear up.

The Convergence Alignment Mode  or simply Convergence Mode is accessed by holding the <Menu> button on the remote until the on-screen menu disappears, then let go of <Menu> and press, in order, <9>, <8>, <7>, <5>, <Enter>. The square determining which point is being modified is moved using the arrow keys and a specific point to be modified may be selected by pressing <Enter>, which will cause the square to blink, at which point the arrow keys will then move the selected point in that direction. Pressing <Enter> again will cause the square to stop blinking and again allow it to move around the screen to a different selection point.  Your changes to convergence will NOT be save if you <quit>, so you may wish to ensure you press <9> followed by <1> then <Enter> periodically to save the changes you have done.

The color that the square is affecting can be cycled through by pressing the <Antenna> button. The square changes to the color that it will move.

You can turn off and on the colors of the grid by pressing the appropriate number. <6> will do Red, <7> will do Green and <8> will do Blue. To turn on only green, for example, press <6> to turn off Red then <8> to turn off Blue. Pressing <6> again would then turn red on again and you would see Yellow on the screen and you could align Red to Green by looking at the edge of the convergence grid lines and seeing which side is red and moving it that direction to align it with green so you only see a yellow line with no red or green on either side (or top or bottom for horizontal lines) of the line. All of which will be more clearly explained in the geometry and convergence section.

You can display whatever input was showing on your screen before entering convergence mode by pressing the Mute button. Note, however, that the convergence grid will remain visible on the screen and that turning on or off any of the colors will only affect that internally generated grid, not the video showing through. So if you wished to use an external grid, for example, you would need to physically cover the CRTs to turn them on or off.

In some situations it may be preferable to use a dot pattern instead of a grid. You can get a dot pattern by pressing <3>.

You can also double the number of visible lines or dots by pressing <4>. This does NOT double the number of convergence points, it just provides more lines/dots if that will assist in your convergence.

You’ll also notice in the upper left of the screen there is a status display. You can toggle this off or back on if you like by pressing <2> depending on your preference or it it obstructs your view of points you wish to converge in that area.

The following is a summary of remote control keys usable in Convergence Mode:

1 – No apparent function

2 – Turn off status display

3 – Dot mode

4 – Double line/dot pattern density

5-<Enter> – Removes all convergence information from grid. (Can be restored with 0-<Enter>)

6 – Toggle Red Gun

7 – toggle green gun

8 – toggle blue gun

9 – Special key that must be followed by another to mode

                9-1 – Save modifications to ATSC

                9-2 – Save (not sure of the difference between this on 9-1)

                9-3 – No apparent function

                9-4 – Pattern Move (Used for centering unconverged grid on screen)

                9-5 – Phase Move (Used for setting horizontal phase to center of screen)

                9-6 – Line # (Appears to move converged grid up or down)

                9-7 – Clamp # (Appears to move only the red converged grid while maintaining the grid location

         for green and blue)

                9-8 – No apparent function

                9-9 – No apparent function

                9-0 – No apparent function

0-<Enter> – Preset From ATSC (loads last saved grid info, discarding any changes made since that time)

<antenna> – Changes active color

arrow keys – Moves either entire grid or just the selection cursor/selection point, depending on mode, in the direction of the arrow.

<quit> – Exit Convergence Mode

Use of some of these keys will be explained  further in the instructions that follow.

It should be noted that depending on what inputs you use, those are the ones your set will be calibrated to. I have found that the RGBHV connection calibrates quite differently from any of the S-Video inputs, for example, but I would rather have my set most properly calibrated for HD and DVD (which I watch through my PC connection to the RGBHV connector) than for the other inputs. There are some service menu items that differentiate the inputs. Those items that have a 21 before them seem to affect all inputs. Those with a 70 before them affect all analog inputs, including the NTSC tuner. While items with BS before them seem to only affect the RGBHV input and possibly the ATSC tuner and component inputs. Please be aware of this while you are performing the below operations for any particular input.

Initial Adjustments

VSB & VCO PCB Adjustment: These would be audio adjustments requiring an insulated driver and a Digital Volt-Meter to adjust. There should be no need for this to be adjusted except by a service tech.

PDO (Phase Detect Output) Adjustment: This adjustment required a Digital Volt-Meter and should also be preformed by a tech.

AGC (Automatic Gain Control) Adjustment: This is also an adjustment set using a Digital Volt-Meter that I can see no need to change except by a tech.

Sub Contrast Adjustment: Zenith recommends this be set with the assistance of an Oscilloscope.  There should be no need to modify this as the standard Contrast Controls should provide the full range you might need. It should be noted that this is performed by modifying service menu item #12, 21 S-Cont. It is possible that the related service menu item #38 S-Con could or should be set with the color setting turned all the way down (so the screen is, effectively, showing a black & white picture) and setting the contrast with it. That is just a guess, though, as I haven’t seen much of a difference between the two settings.

Audio Adjustments

SAP VCO Adjustment: Zenith recommends this be set with the assistance of a Frequency Counter and should probably only be changed by a tech.

Filter Adjustment: Zenith recommends this be set with the assistance of a Frequency Oscillator Generator, Oscilloscope and Modulation Equipment and should probably only be changed by a tech.

Input Level & Stereo Separation Adjustment: Zenith recommends this be set with the assistance of a Frequency Oscillator Generator, Oscilloscope and Modulation Equipment and should probably only be changed by a tech.

Preliminary Alignment Setup

G2 Control Setup: This adjustment is normally set with an Oscilloscope and changes the R-, G- and B-Drive settings to set screen voltage reference level, not gray scale. The gray scale, performed in a later step in these instructions, will probably override these initial settings.

Yoke Tilt Alignment: This requires Physical movement of the CRT yokes and should definitely be considered an advanced operation, but if you want to give it a try here is how it can be done.   This controls how the CRTs are aligned level to your screen. A similar modification (and then some) for a Toshiba set can be found here and it has several good ideas and methods for getting down and dirty with this process and they may prove useful or clearer in explaining the steps that follow.

1.        Go into the Convergence Alignment Mode.

2.        Clear the saved convergence information by pressing <5>, <Enter>,

3.        Turn on only the green grid. (Hit <6> & <8> to turn off Red and Blue)

4.        Loosen the yoke clamping screw on the Green CRT to adjust the tilt of the picture so the center line is completely level across the screen. A crosshatch jig or at least a couple of strips of tape or perhaps a string  to mark the exact center of the screen edges would be very helpful for this as you’ll want that line to not be off by more than 2mm, according to Zenith, and preferably right in line.

5.        Tighten the green yoke clamping screw.

6.        Turn on Red (press 6) and line it up to the green line that is still on the screen.

7.        Don’t forget to tighten up the red yoke clamping screw!

8.        Turn off Red (6) and turn on Blue (8) and line it up to green. If you feel comfortable with your red line you could also try turning off green (7) instead of Red as Blue on Red can sometimes be easier to see than Blue on Green.

9.        Don’t forget to tighten up the blue yoke claming screw when you’re done!

10.     If you are not continuing on to some of the next steps you can restore the original convergence settings by pressing <0> then <enter> to get back that nicely lined up grid that’s probably now a tad off.

X Ray Protection: This adjustment is normally made with the assistance of a Digital Volt-Meter and should probably only be adjusted by a tech.

2-Pole Magnet Adjustment (Raster Positioning): This is another physical adjustment that should be considered an advanced procedure. This controls where the CRT picture as a whole is aligned to your screen.

1.        Still using the Convergence Alignment Mode setup from above leave only the green grid one with the convergence information still cleared. (Press <5> then <Enter> if you had to come back to this if your grid is nice and square as we don’t want the electronic converged information yet.)

2.        You’ll probably notice some white rubbery gunk on your CRT yokes. That is holding all those rings in place so they don’t lose their factory settings while the set is moved. To make these changes you’ll need to pull all of that stuff off so you can freely move the rings. Once your changes are complete you may consider caulking them down again so it will retain your settings if you should need to move the set and take the risk that such movement could vibrate the rings away from where you set them.

3.        On the green yoke move the centering rings to center the green raster on the screen.

4.        On the Red yoke move the centering rings to center the red raster on the screen.

5.        On the Blue yoke, move the centering rings to center the blue raster on the screen.

6.        You can restore the original convergence settings by pressing <0> then <enter> to get back that nicely lined up grid that’s probably now even more than a tad bit off.

Initial Manual Focus

This is another physical adjustment that should be considered a somewhat advanced procedure, but not nearly as difficult as some of the others listed here. This controls the focal point of the CRTs to your screen. You can find another mechanical focus procedure (Cantilever technique) to reference and Projector Focus as well as procedures for mechanical and electronic focus on a Toshiba set at that may prove to be useful references on how to do this.

1.        Unscrew the focus wingnut on the CRTs. Remember this is in the top cavity of the set, not the lower area by the electronics.

2.        Use the Convergence Alignment Mode grid and turn off Red and Blue.

3.        Grab the focus bolt on the green CRT and move it right or left, whichever way will improve the focus. Often rocking back and forth may be required to find the best position. You are looking to see at what point you can see the individual raster lines on your screen that make up the green grid lines.

4.        Tighten the screw taking care that you prevent the focus bolt from moving, as the tightening process can sometimes pull it over very slightly.

5.        Do the same operation for each of the other CRTs. Take note, though, that Blue is notoriously difficult and you may not be able to get it to the point where you can see the raster lines. That is not a problem and is normal. In fact some have suggested that blue should be slightly out of focus in order to ensure it is not overwhelmed by green and red causing a “dinginess” to the color of white.

Astigmatism Alignment

This is another physical adjustment that should be considered an advanced procedure.

These can be useful instructions to reference and compare to these.

1.        Zenith suggests that you make certain the Magnet Astigmator is approximately 45mm from the end of the CRT to begin with.

2.        Go into Convergence Alignment mode (if you aren’t there already).

3.        Change from the normal grid pattern to the Dot pattern by pressing <3>

4.        Turn off Red (6) and Blue (8)

5.        Now we get to screw up your focus, but we’ll use the electronic focus for this because it’s a lot easier to readjust. Turn the Green electronic focus knob to the left.

6.        Adjust the green CRT 2-pole magnet so the middle portion of the middle dot is centered in the halo surrounding it. You may prefer to try this with the crosshatch pattern instead as it may be easier to get the central cross centered in the halo pattern than it is to do this with a dot.

7.        Move electronic focus knob back and forth to check if there is any shift in the center of the dot and if there is go back and try to center it again until there is no shift.

8.        Do the same thing for red and blue.

9.        Go back to green only adjustment (turn off that 6 & 8 again) and turn the green electronic focus all the way to the right.

10.     Adjust the 4 and 6 pole magnets until the central dot on the screen is a perfectly circular.

11.     Then go back and do the same thing for red and blue.

12.     The service manual suggests using silicon adhesive to hold those magnets in place.

13.     Go back and adjust manual focus, if needed, and electronic focus roughly.

Deflection Adjustment

This is for setting the proper horizontal and vertical size of your screen. You will need to have some kind of externally available crosshatch pattern to use for this, such as can be found on the Avia or Video Essentials DVDs, preferably one which shows the amount of overscan. I have found the Avia widescreen pattern… to be best for this purpose. For some good reflections, check out this page on overscan

1.        Bring up your external crosshatch pattern.

2.        Go into the service menu (9,8,7,6,enter)

3.        This is not a required step but if you are going to reduce overscan as absolutely as much as possible then I would recommend changing the values of all the blanking items to their lowers (or highest) setting. This means changing items 21 (Left-BLK), 25 (Left-BLK D), 93 (V_Front_BLK) and 95 (V_Back_BLK) to 0 and 22 (RIGHT_BLK) and 26 (RIGHT_BLK D) to their highest value (I think it is 63), or whatever direction it is that will completely eliminate blanking (move this to their extremes and look at the proper side of the screen to see how a black line appears to reduce light inside your set. We’ll talk about this a bit later on.)

4.        Go to service item 2, H-Size, and adjust it to an overscan marker on the grid pattern you think you can live with. The standard is, I believe, 10% overscan, but 5% is preferable. If you will be using a Home Theater PC (HTPC) you may wish to reduce it even further, but be aware that the less overscan you have the harder it will be to get geometry and convergance on the farthest edges of the screen.

5.        Next select service menu item 1, V-Size and adjust it for overscan in the same way.

Detailed Manual Focus

This is another physical adjustment that should be considered a somewhat advanced procedure, but not nearly as difficult as some of the others listed here. This controls the focal point of the CRTs to your screen. These procedures outline Zenith’s method for properly setting manual focus. I have yet to try them and see how it compares to the initial Manual Focus instructions above or if it even makes sense.

1.        Unscrew the focus wingnut on the CRTs. Remember this is in the top cavity of the set, not the lower area by the electronics.

2.        Use the Convergence Alignment Mode grid and turn off Red and Blue.

3.        Grab the focus bolt on the green CRT and move it to the right   until the chromatic haze (the haze that starts to appear around the lines of the pattern) turns from blue to red.

4.        Tighten the screw taking care that you prevent the focus bolt from moving, as the tightening process can sometimes pull it over very slightly.

5.        Do the same operation for each of the other CRTs. Take note, though, that Blue is notoriously difficult and you may not be able to get it to the point where you can see the raster lines. That is not a problem and is normal. In fact some have suggested that blue should be slightly more out of focus in order to ensure it is not overwhelmed by green and red causing a “dinginess” to the color of white. Although it seems this is more often corrected in adjusting the screen trimpots as mentioned earlier in the manual focus section links and near the end of this manual in the Gray Scale section links.

Electronic Focus

This is another physical adjustment that should be considered a somewhat advanced procedure, but not nearly as difficult as some of the others listed here. This controls the electronic focus of the CRT raster. You may want to reference the Blue Focus tip by Mr Bob for some more into on this.

1.        Use the Convergence Alignment Mode grid and, again, turn off Red and Blue, just like for Manual Focus, above.

2.        Turn the focus pot for green (the central one on the TOP, do not mess with the screen controls on the bottom set of pots as it may cause difficulties later. See the grayscale section for some hints on using these) rocking back and forth, again looking to get the tightest focus where you can see the raster lines. You are trying to improve upon what you accomplished with the manual focus, if possible.

3.        Repeat the procedure for Red and Blue, bearing in mind the notes about Blue mentioned in Manual Focus, above.

4.        It could be said that like so many other procedures outlined here that this process and the process for manual focus are linked, and as such it may prove useful to go back and tighten your manual focus and then electronic focus again. I doubt you will get all that much more improvement out of it, though.

Geometry/Convergence Adjustments

These can be some of the most time consuming, and frustrating, set of adjustments to make.  Be aware that it may take many hours to fine tune convergence to your liking and, depending on the amount of overscan you are allowing for, the edges can be extremely difficult requiring many small changes back and forth between different sections of the screen. It is HIGHLY recommended that you order or make some form of convergence jig that, at the very least, provides straight lines to locate the center of the screen. A few more evenly spaced lines to provide a symmetrical grid pattern to compare your adjustments to can be very helpful in setting a good convergence. A crosshatch jig can be ordered from the Zenith national parts center by ordering part# 868-00119 for the IQB64W10W or Part# 868-00118 for the 56W. It is a mylar sheet that you would slide in-between the lenticular screen and the screen protector that has a grid on it. Personally I do not use my screen protector, so I had previously taped the jig to the screen protector but I have since transferred the pattern directly onto the screen protector making it much easier to put into place.

Horizontal/Vertical Phase Adjustment

This will set the Horizontal and Vertical phase (whatever that is) to proper alignment. This is a fairly simple and easy setup as long as you have your jig showing the central lines on the screen.

1.        Go into convergence alignment mode.

2.        Go into the Phase Move mode by pressing 9 then 5.

3.        Make sure that the center line in the central convex (top of the wave) section is aligned to the middle of the screen by moving it right or left as needed.

4.        Make sure the Arrow on the left is pointing to the center line of the screen by moving it up or down as needed (this will actually make the rest of the grid disappear, so don’t be alarmed by that.)

5.        Press Enter to exit the phase move mode

6.        Press 9 then 1 and enter to save your changes.

Pattern Position Adjustment

This will center the general convergence grid on your screen so you can adjust your geometry and convergence from it correctly later on.

1.        While still in convergence mode enter into pattern shift mode by pressing 9 then 4.

2.        Use your arrow keys to move the grid on the screen until it is perfectly centered. (It should already be pretty close.)

3.        Press Enter to quit pattern shift mode.

4.        Press 9 then 1 and enter to save your changes.

Geometry/Convergence Adjustment

This is where the grueling stuff will begin. The first thing we will do is to try and make the green lines of the grid as straight as possible, also referred to as setting the geometry. Next we will try to line up red to the nice straight green lines and finally line up blue to those green lines (or you can line them up to red if it is much easier for you to see, but green is considered the reference color to work from.) This step of “converging” the other colors to green is often referred to as convergence. Some items of interest to prepare you for this step, and that cover what some of the other steps like this would be on a toshiba convergence tip by Tom Herman. One quick note about the grid, though. You may wish to cut down your contrast and, to some extent, brightness as low as will be comfortable for you to still work with and see the grid. You should also save and exit out to put some normal programming on the screen every 15 minutes to no more than a half hour to limit your chances of burning the grid onto the CRT. Not to mention you should probably take a short break every half an hour anyway or you’ll go nuts doing all of this!

1.        While still in convergence mode press Antenna to change the cursor color to green.

2.        Turn off red and blue (6 & 8)

3.        Starting from the center start lining up the grid to be as straight as possible, the crosshatch jig will be very helpful here. You can select a point to work with by pressing the Enter key and when the selection cursor is blinking it means that when you use your arrow keys that point and some of the surrounding lines will move in that direction. Zenith suggests that points be converged in the following order:

8

6

5

4

5

6

8

7

5

3

2

3

5

7

6

4

2

1

2

4

6

7

5

3

2

3

5

7

8

6

5

4

5

6

8

I have found, however, that there is actually one more set of points on either side not covered by the diagram above, so I suggest the following order:

10

8

6

5

4

5

6

8

10

9

7

5

3

2

3

5

7

9

8

6

4

2

1

2

4

6

8

9

7

5

3

2

3

5

7

9

10

8

6

5

4

5

6

8

10

I have also found that it often works best to do a quick, rough, convergence of all points in the order listed once, then go back for a fine convergence working from the center out, but going back into the center and working back out again in order. I.E. Converge all 10 places first (that’s all 45 points), then converge point 1 followed by points 2. Then go back to converge point 1 again, if it needs it, followed by points 2. Once point 1 and points 2 are converged go on to points 3 and back again to point 1 and so on. You will find that later convergence will mess with earlier ones and that this process helps to lower how badly that occurs, but it is quite time consuming.

Another point of note is that I have found that for points 6, 7 and 8, on the right and left edges, that it is best to converge the next grid line in from those spots, instead of the actual point they are on. (That would be the grid line between points 4 and 6, for example, not point 4). To converge that 6, 7 or 8 point use the next spot out, i.e. use spot 6 to converge the next line in and use spot 8 to actually converge spot 6.

The edges can be the toughest areas to work with and you may need to use some other service menu items to help you get them lined up. If, after you have converged as well as you can, you notice, for example, that the upper right corner angles outwards and you just can’t get it fixed, you could try to angle out the upper right corner about the same amount, then save your convergence, exit the mode and pull up an external crosshatch pattern. Enter the service menu and select item 72 (UP_CPIN). It may help to cover your red and blue lenses with something like a magazine so you can see the effect this will have on your green grid. You could then decrease your Upper Corner Pincushion (what UP_CPIN stands for) value to pull those upper edges in, or increase if you need to move them out. There are several other geometry altering service menu items like this that may be useful for some of the difficult screen areas, but even these can’t fix everything, so you may still be hard-pressed in spots and have to live with a compromise of getting it the best that you can or by increasing overscan to cover up those problem edges so you won’t see them.

Geometry affecting service menu items that I know about are numbered 28, 29, 30, 31, 32, 35, 36, 70, 72, 73, 86, 87, and 88. Check out the service menu listing for the specifics.

Be certain that you do a 9, 1, Enter every now and then to save what you’ve done! You’ll hate yourself if you have to start all over again because you accidentally hit quit.  It also might be good for you and your set to quit out of the convergence grid every 15-30 minutes (or even more often, remember that Zenith recommends 10 mins.) to help prevent burn-in for your screen and to prevent burn-out for you!

Whew! See what I mean about this being pretty involved. And we’ve only done green!

4.        Be sure to do a 9, 1, enter to save before continuing on to step 5!

5.        Next switch to a red cursor with the antenna button

6.        Turn off  only blue (8) leaving green on.

7.        Line up red over the green lines so you see yellow lines. Just keep an eye on the edges to see if they look red on one side (or green on one side if that is easier for you) and move the points to try and get rid of that. Just do this in the same way you did green and don’t forget to save! (9,1,enter)

8.        Of note for red is that if you are having some problems lining up those edges there is one other thing you can try that may help by moving the entire red grid right or left. Just press 9 then 7 and you will see your grid and the word Clamp followed by a number on your status display. You can increase or decrease that number to move just the red grid to the right or left. I have found this helpful where I was having trouble getting red to move far enough to the left to match up to its corresponding green line. I’m not sure what, if any, other function this “clamp” movement performs.

9.        Once you have red adjusted (and saved!) then switch your cursor to blue and turn off red and turn on blue to line up the blue lines onto the green to give you cyan. Just look for edges that are blue or green to line these up. If you find this extremely difficult then lining blue up onto red (giving magenta lines) may be easier for you. No matter how you look at it, though, blue is a tough one on the eyes and can be hard to work with. I definitely recommend frequent breaks when working with blue.

10.     Save! (9,1,enter)

Final Adjustments

OSD Position Adjustment: This simply adjusts the location of your On-Screen Display. It may prove useful in getting the text a bit lower on your screen or to make sure it is nicely centered on your screen, or whatever you prefer. This is mostly an aesthetic choice but lowering its position may assist in working with some test patterns when you have something displayed on the screen. However, I don’t believe this will affect the position of the Main Menu, so your Contrast, Tint and Sharpness adjustments are still in that annoying spot on the left-center of the screen no matter what this is set at.

1.        Enter service mode.

2.        Modify 18 (OSDHPOS) to move the OSD up and down on the screen to your preferred position.

3.        Modify 150 (OSDVPOS) to move the OSD side-to-side on the screen to your preferred position.

White Balance Adjustment: This is an adjustment to mainly set your contrast level to the factory suggested settings, although it can, and probably should, be set lower than this.  To set it to their specifications requires a Brightness meter and a 100% white signal. They recommend that your green cutoff  (set in G2 Control Setup requiring an Oscilloscope) and focus adjustments be complete before this. Please note that I do not have a brightness meter and have never performed this operation, so some of this may be my misreading of the service manual description. If anyone is actually familiar with this operation, please let me know if these procedures need to be changed to correctly reflect this operation.

1.        Make sure your room is kept dark for this procedure.

2.        Place the brightness meter 3 meters away from the center of the screen.  (Unless in 3M distance means something else that I’m not aware of.)

3.        Adjust the brightness meter focus to the focus on the optical screen and set the Field Degree to 1c.

4.        Make sure the screen ration format is 16:9 (press the ratio button if needed.)

5.        Provide a 100% white 100IRE signal pattern to the screen. Avia or Video Essentials  as well as some THX certified DVDs have this pattern.

6.        Set contrast to 100, Brightness to 60 and Color to 50.

7.        Go into the service menu and make sure the data of item 3 through 8 are set at 32 (that’s R-Drive through B-Cutoff).

8.        Pressing the Mute button here allows you to select which mode, W(arm), M(edium), or C(ool), you wish to modify. Following will be the Zenith suggestions. The manual recommends that your check  to make sure that 3 through 8 are 32 for all modes before making the following changes.

9.        For Medium adjust 3 (R-Drive) and 4 (G-Drive) so that the color coordinates on the brightness meter red x=296 and y=303 (8000cK-5MPCD)

10.     For Cool adjust 3 (R-Drive) and 4 (G-Drive) so that the color coordinates on the brightness meter red x=282 and y=286 (10000cK-5MPCD)

11.     For Warm adjust 3 (R-Drive) and 4 (G-Drive) so that the color coordinates on the brightness meter red x=313 and y=320 (6500cK-5MPCD)

12.     Check back through each of your settings to ensure the data returns remain consistent and make any changes as necessary to line them back up.

Sub-Bright, Sub-Tint and Sub-Color Adjustments: The service manual recommends that these be set with a “color bare pattern” and an SMPTE pattern. I have not looked for or used the first pattern, but the second could be used in place of it and can be found on the Avia and Video Essentials DVDs as well as some of the THX certified DVDs that have test patterns on them.

1.        If using a bare color pattern Zenith recommend changing 9 (S-Bright) to match the box 2 level. On an SMPTE pattern or on any brightness level pattern that you may have adjust your black level as those tests are explained to work.

2.        Next pull up an SMPTE color pattern (or “Blue Bars” color pattern on Avia if you prefer).

3.        Cover the red and green CRT lenses with a magazine or some other opaque object being careful not to scratch or smudge the lenses.

4.        Set service menu item 11 (Sub-Color) in the same way you would the color adjustment for these patterns. (It is explained fully on those test DVDs)

5.        Set service menu item 10 (Sub-Hue) in the same way as described for hue or tint on these patterns.

Other Possible Tweaks

That is it for what the service manual covers beyond circuit board patterns and description. Form here on out you will find a few things that I have discovered that may assist in improving your image. First off I highly recommend a test DVD such as Avia or Video Essentials as those will provide test patterns and tell you how to modify your user modifiable parameters (such as sharpness and contrast and such) optimally. Below I will concentrate on service menu modifiable parameters and as such it implies that the normal user modifiable parameters not be changed from their default settings just yet. At least not until after the service menu items are set to your satisfaction first.

DC Restoration: First off I have found that properly setting Black Level, such as for Sub-Bright above, is almost impossible when the service menu is up because the set seems to adjust its brightness level based on the brightest areas of the screen. For example if you have a mostly black screen with some very dim information on it (such as Avia’s Black Bars test pattern) and press the <Picture> button on the remote to pull up the Contrast and Brightness settings to change them, you will notice that while the blacker than black bar may have been just visible before, it is not visible or less visible now that this bright display is on the screen. So if you set your brightness now will it be too high or too low? Setting service menu item 112 (21 DC-Tran) to 0 seems to alleviate some of this problem and should improve your black level slightly. I’d go back and set your Sub-Bright from above after making this change.

ABL: Automatic Brightness Limiter effects may also affect black level as mentioned in DC Restoration to some extent. Service menu items 41 (P_ABL-L), 46 (21 ABL Mode) and  108 (21 ABL-TH) may have some effect on this, but I have yet to test what those effects may be.

Blanking In order to improve black level further it is helpful to reduce the amount of light that may be bouncing around inside of your set. Preferably you want all of the light to be going straight to the screen and not to any other parts inside of your set. Blanking can be used to help mask off the areas of your CRTs that are shining outside of your viewable screen. I have not found the difference between 21 (Left_BLK) and 25 (Left_BLK_D) or 22 (Right_BLK) and 26 (Right_BLK_D), yet. So I simply set both of them at the same time. For 21 (and 25) increase the numbers until you see a black bar encroach upon your screen then decrease the number until it is just no longer visible. For 22 (and 26) decrease the number until the black bar comes onto screen and then increase it to get it just off the edge again. I believe that both 93 (V_Front_BLK) and 95 (V_Back_BLK) act like the left blanking in that by increasing them the black bar will encroach upon the screen (on the bottom for 93 and on the top for 95) and you will decrease the value to just get the bar back off of the screen. As a side not you can reduce light reflections inside of your set further by putting Duvetyne or a black velveteen fabric inside of the set to help absorb stray light, as the plastic inside of the set does have a slight sheen to it. I recommend looking into Black Level  for some suggestions on doing this. The first item there “Software” refers to the method just explained here as Blanking, while the “Felt-ware” and “Duve-ware” methods are those describing the lining of the set with fabric.

Gamma Correction: Avia has a test pattern and explanation of gamma. You can use it along with service menu item 44 (Gamma) to ensure you have a good gamma setting.

CTI Level: I have been told that CTI level impacts color overlap in bar patterns. As such it may be helpful to change 47 (21 CTI_Level) to reduce that overlap. Increasing it appears to reduce the overlap while decreasing it appears to increase the overlap.

Variable Q: It is possible that 48 (21 S-Sharp) is not so much a Sub-Sharpness control as an adjuster for Variable Q. Variable Q is the amount of bandwidth used in a video peaking frequency which may suggest how much of a bandwidth area the sharpness control will affect. If this is the case then lowering this value means a wider bandwidth of video frequencies that will be affected by the sharpness control. As such, raising this value should help to reduce how much of a frequency is affected by sharpness modification.

Sharpness: It is possible that 48 (21 SHP_F0) controls Sub F0 control for NT, which I believe is related to sharpness. I am unsure of in what way, however. 49 (21 Pre-Over) probably has something to do with Sharpness Pre/Overshoot Gain but I am unsure in what way it can be changed to reduce sharpness modification of a signal. Finally, 51 (21 LTI-Level) probably has something to do with Sharpness Y edge level enhancement and reducing it may reduce sharpness modification of a signal. In user controls I have my user accessible sharpness set to 0, but perhaps you will find a better setting using one of the test DVDs. I have seen it suggested here that some of these settings (referred to there as SHPF, for SHP_F0, SSHP, for S-Sharp, and PREO, for Pre-Over) may affect signal sharpness without adding edges.

Velocity Modulation: Velocity Modulation, sometimes referred to as Scan Velocity modulation or SVM (or even VSM), modifies a signal in a similar manner to sharpness. As such reducing or disabling SVM is preferred. Supposedly the Zenith does have SVM but I do not believe it is very strong as set at the factory. There may be a way to completely disable SVM, but I do not, as of yet, know how. Although I have been told that the selectable video modes defeat SVM. (Some of the Toshiba sets are said to work this way as noted in the last link listed in this section.) The following service menu items, however, may be modified to reduce and possibly remove its influence. 52 (21 VM-Lev) may be a setting for Velocity Modulation Level and its default setting is 0, which is where I would expect to put it to obtain the least amount of SVM. 53 (21 VM-Del) may concern VM Delay and the default of 0 may be the best setting. 120 (21 YSYM1SW) may be YS/YM-1 Switch off/on which also has something to do with VM and the default setting of 0 would imply this is off, which may be the optimal setting. Finally 121 (21 YM-VM) is probably another setting dealing with SVM, but I am unsure of in what manner. Changing it to 0 may turn off any modifications this setting was making on behalf of VM and therefore be the optimal setting. For more info about SVM, go here for more info and here for info from Michael TLV.  

Dynamic Picture: It is possible that 54 (21 D-Pic) is a dynamic picture function for the set which would probably affect black level, perhaps in a similar way to DC Restoration and ABL. In which case changing this to 0 to turn it off may be preferable. However it may actually improve black level leaving this on. I haven’t experimented enough with it to make a good determination as of yet.

Dynamic Color: 55 (21 D-Col) may be a dynamic color setting, which would change color based on APL. In other words the set is trying to make color compensations based on the signal received. If this is so this would probably be best if set to 0 to turn it off.

Y/C Delay: Avia also has a pattern for detecting Y/C Delay levels. I don’t yet know what can be used to correct any errors that this test may show.

Z Cut: 85 (ZCUT) may be a setting affecting image jitter. It may be possible to eliminate some of the jitter in an image, if you are having that problem, but changing this to 1 to turn it on. I leave mine at 0.

White Balance: It has been suggested to me that there are several other items which can be used to affect white balance beyond the modifications of 3 (R-Drive) and 4 (G-Drive) as mentioned above in the service manual. 98 (21 CR-OFFset1) and 99 (21 CR-OFFset2) may affect the red offsets while 101 (21 CB_OFF1) and 102 (21 CB_OFF2) may affect the blue offsets. (Although the white balance adjustments from the manual use red and green.) I am not sure what the best method for utilizing these offsets would be.

Grey Scale: This is normally an adjustment performed by an ISF calibrator or through the use of a colorimeter. There are other sources to explain the procedure and there are sources for renting a colorimeter if you wish to really ensure your set looks it’s best by configuring your Warm color setting to be set at a color rating of 6500 Kelvin. Zenith appears to recommend a setting of 10,000 Kelvin for Cool and 8,000 Kelvin for Medium (and they do actually recommend 6,500K for the Warm setting). If you want to know why 6500K is what you are aiming for check out this pagel. Also there is some indication that the screen trimpots (those black knobs under the electronic focus trimpots) can be used for this purpose. Check out these links

Saturation Levels: Finally you can set the saturation levels to get the proper color settings not just for Blue (like you do when setting your Color and Tint settings), but for green and red as well. To set red you will use the color bar pattern exactly like you would for blue, except you will be matching the levels for all of the red containing bars and by modifying 39 (21 R-Y/R or Red levels in Yellow/Red) and 42 (21 R-Y/B or Red level in Yellow/Blue) in much the same way as if those were the Color and Hue settings for Blue. Do the same for green containing bars by covering Red and Blue and using 40 (21 G-Y/R or Green levels in Yellow/Red) and 43 (21 G-Y/B or Green levels in Yellow/Blue) in the same way. Go back and forth between setting all of these, checking your Blue, Red and Green levels and fixing them until they all become level as modifying one of them sometimes introduces slight errors into the others until they are all leveled out. An explanation of this and how it is different from grayscale adjustments can be found at this page.

The best thing to do now would be to use a test DVD to go back and set all of your user accessible settings to give you the best picture (such as by cutting that sharpness down) then go back again to set your saturation levels and your gray scale as it is possible that some of the changes you make may affect it. Everything seems to affect everything else but the closer you get with each the less error seems to be introduced into other settings.

Best of luck and happy calibrating!